Outside Plant
Design Reference
Manual
Fourth Edition
A Truly Unique Outside Plant Manual
With the release of this 4th edition of BICSI’s Customer-Owned Outside Plant (CO-OSP) Design
Manual, the name has been changed to Outside Plant Design Reference Manual (OSPDRM). In the
opinion of both the writers and the BICSI Technical Information and Methods (TI&M) Committee as a whole,
this name change reflects a broader applicability of the information contained in the manual. In today’s OSP
marketplace, the lines between customer-owned and other information transport systems (ITS) infrastructure
have blurred. Following this same trend, the need for a design reference manual specifically focused on
customer-owned facilities has become less important. The information contained within this new fourth edition
is useful for anyone who is involved in the design or construction of OSP projects. The TI&M Committee,
BICSI’s Board of Directors, and the writers of the new edition all agree that we invite a broader and more
appropriate readership by changing the name for this latest edition. With this in mind, the new 4th edition of the
OSPDRM is truly unique in many ways.
First of all, it is the next in a series of BICSI manuals revised to address global best practices, which makes it
more accommodating and beneficial not only to our United States members but to our large international
membership as well. The use of the term “BICSI best practices” rather than country specific references should
clearly indicate the efforts to achieve this goal. Please note that relevant codes and standards applying to each
chapter are listed at the backs of each, and a full and comprehensive listing of all codes, standards, and
regulations for the entire manual appear in a new Appendix A at the back of the manual.
Secondly, I had a talented Subject Matter Expert (SME) volunteer team possessed with a wealth of OSP
knowledge and a true dedication to making the fourth edition a success. Their creativeness, respect for opinions,
and common cause attitude was indeed a pleasure to witness. Please see page i of the Preface for a listing by
chapter of all their names, credentials, and organizations.
Third, and of utmost importance, is the new Chapter 2: Legal Considerations for the OSP Designer. This chapter
was a blessing in that it provides the reader with some of the potential issues and problems that the OSP
designer may encounter. As we have stated many times before, OSP is inherently dangerous and good designers
need to protect themselves and their clients from physical as well as legal damages.
And last, but certainly not least, was the excellent support of BICSI’s Publications staff, who knew enough to
stay out of the technical jargon but were also wise enough to tighten the reins when we needed it. Those
talented individuals were Lead Editor Karen Jacob; Co-Editors Joan Hersh and Nermina Miller (under
contract); Senior Editor Clarke Hammersley; and Publications Design Facilitators John Ditzel and Danielle
Fernandez. Their attitude and skills, coupled with the talent of the OSP SME team, created the dream that we
all had in the beginning: the best OSP manual ever.
However, I’d be remiss if I didn’t recognize the talents of those individuals who produced the past OSP
manuals. Their efforts created the foundation of our new manual to which we further expanded upon.
The reader will also notice that the air pressure section has been relocated to the new Chapter 13: Special
Design Considerations. This subject matter wasn’t moved to indicate that air pressure isn’t still around.
Although air pressure is not recommended for new OSP design, it still must be recognized because it’s still
out there and therefore must be addressed.
Chapter 3: Cable Types contains new charts and illustrations to further accent the use of optical fiber cable,
yet still addresses the needs and concerns of those designers that choose to use other media such as coaxial
or copper twisted-pair cables.
Chapter 7: Grounding, Bonding, and Protection inevitably had to be changed for several reasons. The first
objective was to match the new 11th edition of the BICSI Telecommunications Distribution Methods
Manual (TDMM) grounding and bonding chapter as closely as possible. And next, to address some of
the changes to the world of “black magic.”
Chapter 11: Cost Estimating also was revisited to update some of the methods and drawings to make for a
clearer picture for the new designer or estimator. This section should greatly improve the thoroughness of
future proposals.
And finally, Chapter 13: Special Design Considerations should be extremely beneficial to those designers with
limited experience overbuilding existing infrastructure. This chapter is an excellent beginning in an attempt to
better understand why overbuilds are not as easy as we had previously thought.
In closing, the OSP SME volunteer team hopes in some small way that this fourth edition of the OSP manual
will make the reader more aware of the complexity of OSP design and installation and that the knowledge
gained by using this new manual becomes an asset to you and your customers.
Respectfully,
John C. Adams
RCDD/OSP Specialist
TI&M OSP SMETL
Thank you for ordering the Outside Plant Design Reference Manual, 4th edition, 2007. Please place the
chapter tabs in front of the title page for each chapter. The section tabs should be inserted in front of the
following pages:
Chapter 5: Pathways and Spaces
5-1
Underground Pathways
5-73
Dirct-Buried Pathways
5-85
Aerial Pathways
5-147
Aerial Construction Practices
5-187
Spaces
We welcome all comments about this manual. If you have any questions about BICSI and its services, please
contact our office at 800.242.7405 (USA/Canada toll free); +1 813.979.1991; fax +1 813.971.4311; e-mail
bicsi@bicsi.org; Web site www.bicsi.org.
Outside Plant
Design
Reference
M A N U A L
4th Edition
BICSI®, Tampa, FL 33637
© 2007 by BICSI®
All rights reserved.
Fourth edition published 2007
First printing February 2007
Printed in the United States of America
All rights reserved
ISBN 1-928886-38-8
All brand names, trademarks, and registered trademarks are the property of their respective holders.
No part of this manual may be used, reproduced, or transmitted in any form or by any means, electronic
or mechanical, including photocopying, recording, or by any information storage and retrieval system,
without prior agreement and written permission from the publisher.
The contents of this manual are subject to revision without notice due to continued progress in
methodology, design, and manufacturing in the information transport systems (ITS) industry.
THIS MANUAL IS SOLD AS IS, WITHOUT WARRANTY OF ANY KIND, RESPECTING THE
CONTENTS OF THIS MANUAL, INCLUDING BUT NOT LIMITED TO IMPLIED
WARRANTIES FOR THE MANUAL’S QUALITY, PERFORMANCE, MERCHANTABILITY,
OR FITNESS FOR ANY PARTICULAR PURPOSE. BICSI SHALL NOT BE LIABLE TO THE
PURCHASER OR ANY OTHER ENTITY WITH RESPECT TO ANY LIABILITY, LOSS, OR
DAMAGE CAUSED DIRECTLY OR INDIRECTLY BY THIS MANUAL.
BICSI World Headquarters
8610 Hidden River Parkway
Tampa, FL 33637-1000 USA
Tel.: +1 813.979.1991 or
Tel.: 800.242.7405 (USA & Canada toll-free)
Fax: +1 813.971.4311
E-mail: bicsi@bicsi.org
Web: www.bicsi.org
Thank you for ordering the new fourth edition of BICSI’s Outside Plant Design Reference Manual
(OSPDRM). The officers and directors of BICSI are pleased to provide an up-to-date reference manual
that offers proven design guidelines and methods accepted by the information transport systems (ITS)
industry. Volunteers outside the United States and Canada have provided valuable input to make the newest
edition of the OSPDRM a valuable tool for an international audience.
As an ITS association, BICSI serves the industry by providing excellent opportunities to learn new
technologies through the Registered Communications Distribution Designer (RCDD®) registration program,
Network Transport Systems (NTS), OSP, and Wireless Design (WD) Specialty enhancements,
telecommunications distribution design and installation courses, and several educational conferences each
year.
If you have questions about BICSI and its services, please contact our office at 800.242.7405 (USA and
Canada toll-free) or +1 813.979.1991; fax: +1 813.971.4311. You also may contact BICSI via e-mail
(www.bicsi.org) and our Web site (bicsi@bicsi.org). We welcome your comments about the OSPDRM.
To do so, simply complete the Reader’s Comment Form on the last page of the Preface of this manual and
return it to BICSI. Our goal is to make BICSI publications the most important design and reference tools
in your office.
John Bakowski, RCDD/NTS/OSP/WD Specialist, President
Edward J. Donelan, RCDD/NTS Specialist, President-Elect
Brian Hansen, RCDD/NTS Specialist, Treasurer
Steve Calderon, RCDD/NTS/OSP Specialist, Secretary
Christine Klauck, RCDD/NTS Specialist, U.S. Northeast Region Director
Charles Wilson, RCDD/NTS/OSP Specialist, U.S. Southeast Region Director
Jerry Bowman, RCDD/NTS Specialist, U.S. North-Central Region Director
James Ray Craig, RCDD/NTS Specialist, U.S. South-Central Region Director
David A. Richards, RCDD/NTS/OSP Specialist, U.S. Western Region Director
Roman Dabrowski, RCDD, Canadian Region Director
Brendan Greg Sherry, RCDD/NTS/WD Specialist, European Region Director
David C. Cranmer, RCDD, Executive Director and CEO
WARNING
It is the responsibility of the user of this manual to determine the use of the applicable local, regional, state,
or international safety and health practices associated with outside plant (OSP) installation and design
practices. BICSI shall not be liable to the purchaser or any other entity with respect to any liability, loss or
damage caused directly or indirectly by application or use of this manual. No project is so important, nor
any completion deadline so critical, to justify nonconformance to OSP industry standards. This manual
does not address safety issues associated with its use. It is the OSP professional’s responsibility to use
established and appropriate safety and health practices and to determine the applicability of all regulatory
issues.
Acknowledgments
BICSI’s Technical Information and Methods (TI&M) Committee serves to coordinate the information within
all of BICSI’s technical publications. BICSI officers, membership, and staff wish to thank the TI&M
Committee and the many Subject Matter Expert (SME) volunteer contributors who helped in the
development of the fourth edition of BICSI’s Outside Plant Design Reference Manual (OSPDRM).
The following dedicated Subject Matter Expert Team Leaders (SMETLs) and SMEs provided the
key expertise required for the development of this manual:
TI&M OSP SMETL:
John Adams, RCDD/OSP, Adams Telecomm
Chapter 1
Chapter SMETL:
George M. Fewell, RCDD, Independent Consultant
SME Contributor:
Robert Y. Faber Jr. RCDD/NTS, Siemon
Chapter 2
Chapter SMETL:
Meg Gibson-Henlin, BICSI Member, N2N Networks Limited
Legal Considerations for the
OSP Designer
SME Contributors:
Jerry L. Bowman, RCDD/NTS, CISSP, CPP, CommScope
Enterprise Solutions
Chapter 3
Chapter SMETL:
Terri M. Brown, Superior Essex
SME Contributors:
Stephen Banks, RCDD, Nightlake Limited
Edward Brower, RCDD/OSP, Bellsouth Communication
Systems
Robert Y. Faber Jr. RCDD/NTS, Siemon
Daniel Graff, Emtelle US, Inc.
Overview
Cable Types
Robert M. Gross, RCDD/OSP, The Benham Companies
Steve Szymanski Jr., Prysmian Cables and Systems
Chapter 4
Cabling
Infrastructure
Chapter SMETL:
Robert M. Gross, RCDD/OSP, The Benham Companies
SME Contributors:
Kerry A. Engmark, RCDD, Kearney Electric-Communications
Robert Y. Faber Jr. RCDD/NTS, Siemon
Herbert (Butch) Gall, RCDD, General Dynamics
Joe A. Hite, RCDD/OSP, CT Communications
Randall Holt, RCDD/OSP, Puka Enterprises, Inc.
© 2007 BICSI®
i
OSP Design Reference Manual, 4th edition
Acknowledgments, continued
Chapter 5
Pathways and
Spaces
Chapter SMETLs:
Section Contributors:
Joe A. Hite, RCDD/OSP, CT Communications
Edward Brower, RCDD/OSP, BellSouth Communication
Systems
Kerry A. Engmark, RCDD, Kearney Electric-Communications
Robert Y. Faber Jr. RCDD/NTS, Siemon
Victor D. Phillips, RCDD/OSP, TPM, CTBO, Information
Transport Systems Designers International
Chapter 6
Chapter SMETL:
Herbert (Butch) Gall, RCDD, General Dynamics
Splicing
Hardware
SME Contributors:
Robert Y. Faber Jr. RCDD/NTS, Siemon
Robert M. Gross, RCDD/OSP, The Benham Companies
Randall Holt, RCDD/OSP, Puka Enterprises, Inc.
Chapter 7
Chapter SMETL:
Kenneth Michaels, CPU, BellSouth Communication Systems
Grounding,
Bonding,
and Protection
SME Contributors:
Kerry A. Engmark, RCDD, Kearney Electric-Communications
Robert M. Gross, RCDD/OSP, The Benham Companies
Philip W. Janeway, RCDD, Time Warner Telecom
Chapter 8
Chapter SMETL:
Charles (Chuck) Lohrmann, RCDD/OSP, TPM, Compass
Telecommunications Consulting Corporation
SME Contributors:
Robert Y. Faber Jr. RCDD/NTS, Siemon
Philip D. Klingensmith, RCDD/OSP, Compass
Telecommunications Consulting Corporation
Chapter SMETL:
Dan L. Munson, RCDD, Leviton
Chapter SMETL:
William A. Boyd, RCDD/OSP, Indianapolis Electric
Company, Inc.
SME Contributors:
Philip W. Janeway, RCDD, Time Warner Telecom
Captain Donald E. Nelson, RCDD/WD, Nelson Consulting
Associates
Chapter SMETL:
Kerry A. Engmark, RCDD, Kearney Electric-Communications
Right-of-Way
Chapter 9
Scope of Work
Chapter 10
Design
Documentation
Chapter 11
Cost Estimating
OSP Design Reference Manual, 4th edition
ii
© 2007 BICSI®
Acknowledgments, continued
Chapter SMETL:
Bob DeGarceau
Chapter SMETL:
Richard S. King, RCD®/NTS/OSP/WD, TKG Consulting
Engineers,Inc.
SME Contributors:
Jeffery A. Beavers, RCDD/OSP, Henderson Engineers, Inc.
Robert Y. Faber Jr. RCDD/NTS, Siemon
Herbert (Butch) Gall, RCDD, General Dynamics
Robert M. Gross, RCDD/OSP, The Benham Companies
Joe A. Hite, RCDD/OSP, CT Communications
Philip W. Janeway, RCDD, Time Warner Telecom
Dan L. Munson, RCDD, Leviton
Overall
Chapter
Reviews
SMETLs:
J. Carl Bonner Jr., RCDD/OSP,/WD, Network
Communications Supply Company
R.S. (Bob) Erickson, RCDD/NTS/OSP/WD,
Communications Network Design
Victor D. Phillips, RCDD/OSP, TPM, CTBO, Information
Transport Systems Designers International
Appendix A
SME Contributors:
Entire OSPDRM Team
Chapter 12
Maintenance
and Restoration
Chapter 13
Special Design
Considerations
Codes, Standards,
and Regulations
Glossary
Robert Y. Faber Jr. RCDD/NTS, Siemon
Index
Nermina Miller (under contract)
© 2007 BICSI®
iii
OSP Design Reference Manual, 4th edition
Participants, OSPDRM 4th edition Editorial Review, Tampa, FL, August 17-19 2006:
John Adams, RCDD/OSP; Jeffery A. Beavers, RCDD/OSP;
William A. Boyd, RCDD/OSP; Terri M. Brown, BICSI
Member; Bob DeGarceau; Kerry A. Engmark, RCDD; R.S.
(Bob) Erickson, RCDD/NTS/OSP/WD; Robert Y. Faber Jr.,
RCDD/NTS; Herbert (Butch) Gall, RCDD; Joe A. Hite,
RCDD/OSP; Philip W. Janeway, RCDD; Richard S. King,
RCDD/NTS/OSP/WD; Charles (Chuck) Lohrmann, RCDD/
OSP, TPM; and Dan L. Munson, RCDD.
BICSI staff attending:
John Ditzel, Danielle Fernandez, John Fitzpatrick,
Clarke W. Hammersley, Joan Hersh, Karen Jacob,
Colleen McIlroy, Amy Rohr, and Ron Shaver.
The following BICSI Professional Development staff members produced this manual at BICSI World
Headquarters, Tampa, FL.
Director of Professional Development:
Richard Dunfee, RCDD/OSP
Manager of Publications and Curriculum: Ron Shaver, RCDD/NTS/OSP/WD, Master Instructor
BICSI OSPDRM Project Manager/
Senior Technical Editor:
Clarke W. Hammersley
OSPDRM Lead Technical Editor:
Karen Jacob
OSPDRM Technical Co-Editors:
Joan Hersh, Nermina Miller (under contract)
Design and Production:
Danielle E. Fernandez, Senior Publications Design Facilitator
John Ditzel, Publications Design Facilitator
Mason Bond, Web Assistant
Nermina Miller (under contract)
OSP Design Reference Manual, 4th edition
iv
© 2007 BICSI®
BICSI Policy for Numeric Representation of Units of
Measurement
BICSI technical manuals primarily follow the modern metric system, known as the
International System of Units (SI). The SI is intended as a basis for worldwide standardization
of measurement units. Generally, units of measurement in this manual are expressed in SI
terms, followed by an equivalent imperial (U.S. customary) unit of measurement in
parentheses (see exceptions listed below):
© 2007 BICSI®
•
In general, SI units of measurement are converted to an imperial unit of measurement
and placed in parentheses. Exception: When the reference material from which the value
is pulled is provided in imperial units only, the imperial unit is the benchmark.
•
In general, soft (approximate) conversions are used in this manual. Soft conversions
are considered reasonable and practicable; they are not precise equivalents. In some
instances, precise equivalents (hard conversions) may be used when it is a:
–
Manufacturer requirement for a product.
–
Standard or code requirement.
–
Safety factor.
•
For metric conversion practices, refer to SI 10-02 American Society for Testing and
Materials (ASTM)/Institute of Electrical and Electronics Engineers® (IEEE) SI 10,
American National Standard for Use of the International System of Units (SI):
The Modern Metric System.
•
Trade size is approximated for both metric and nonmetric purposes. Example: 100 mm
(4 trade size).
•
American wire gauge (AWG) and plywood are not assigned dual designation SI units.
Dimensions shown in association with AWGs represent the equivalent solid conductor
diameter. When used in association with flexible wires, AWG is used to represent
stranded constructions whose cross-sectional area (circular mils) is approximately
equivalent to the solid wire dimensions provided.
•
In some instances (e.g., optical fiber media specifications), the physical dimensions
and operating wavelengths are designated.
•
When Celsius temperatures are used, an equivalent Fahrenheit temperature is placed
in parentheses.
v
OSP Design Reference Manual, 4th edition
OSP Design Reference Manual, 4th edition
vi
© 2007 BICSI®
About BICSI… Advancing Information Transport Systems
BICSI Vision Statement
BICSI® is the worldwide preeminent source of information, education, and knowledge
assessment for the constantly evolving ITS industry.
BICSI Mission Statement
BICSI’s mission is to:
•
Lead the information transport systems industry with excellence in publications, education,
and knowledge assessment.
•
Advance our members’ ability to deliver the highest quality products and services.
•
Provide our members with opportunities for continual improvement and enhanced
professional stature.
Supporting the Information Transport Systems (ITS) Industry
BICSI is a professional association supporting the information transport systems (ITS) industry
with information, education, and knowledge assessment for individuals and companies. BICSI
serves more than 25,000 ITS professionals, including designers, installers, and technicians. These
individuals provide the fundamental infrastructure for telecommunications, AV, life safety,
electronic safety and security (ESS), and automation systems. Through courses, conferences,
publications, and professional registration programs, BICSI staff and volunteers assist ITS
professionals in delivering critical products and services, and offer opportunities for continual
improvement and enhanced professional stature.
Headquartered in Tampa, Florida, BICSI membership spans nearly 90 countries.
For more information, contact BICSI at 800.242.7405 (USA and Canada toll-free) or
+1 813.979.1991. You may also e-mail bicsi@bicsi.org or visit www.bicsi.org.
© 2007 BICSI®
vii
OSP Design Reference Manual, 4th edition
Become a BICSI Member!
BICSI membership is your key to a successful career in the ITS industry. Member benefits
extend into the technical, legislative, and even the financial realms of this competitive industry.
Membership offers ample opportunities for professional networking and career development
and advancement. Membership is open to individuals and corporations serving the ITS and
building industries. Join BICSI and combine your expertise with your colleagues in the
network of ITS professionals.
Member Benefits
Gain the Competitive Edge!
Combine all the benefits of BICSI membership into one complete package and you will
understand why BICSI members hold a competitive advantage. BICSI keeps you ahead of
your competition through a continuous flow of new information in the fast-changing field of
low-voltage distribution systems. By prominently displaying your BICSI membership, you
make known your professional ability to industry contacts.
Fast Access to Information
BICSI’s Web site (www.bicsi.org) has been completely reformatted and is a quick way to
find a wide variety of detailed BICSI information. While on the Web, find answers to industry
questions and communicate with members and colleagues through BICSI’s online forums.
Search for BICSI members, installers, and RCDDs. Corporate members also have the option
of providing a brief company description and a link to their Web site.
Member Discounts
BICSI members receive substantial discounts on quality education—manuals, design courses,
and conferences. BICSI members also receive discounts on Telecommunications Industry
Association (TIA) cabling standards, Cabling Standards Update Newsletter, industryrelated reports, Continental Automated Buildings Association (CABA) conferences, and
Society of Cable Telecommunications Engineers Inc. (SCTE) products and conferences.
Members can also enroll in many InfoComm International® AV courses at BICSI member
prices. In addition, BICSI offers health, dental, vision, disability, term life, accidental death
and dismemberment, and errors and omissions insurance rates for yourself and your
company.
OSP Design Reference Manual, 4th edition
viii
© 2007 BICSI®
Member Benefits, continued
International Credentials
BICSI’s professional registration programs are internationally recognized.
RCDD® • RCDD/NTS Specialist • RCDD/OSP Specialist • RCDD/WD Specialist
Registered Installer, Level 1 • Registered Installer, Level 2 • Registered Technician
•
The title Registered Communications Distribution Designer (RCDD®) is awarded to
BICSI members who demonstrate expertise in the design, implementation, and integration
of telecommunications and data communications transport systems and related
infrastructure components.
•
Designed to enhance the RCDD, the Network Transport Systems (NTS) Specialty
(RCDD/NTS Specialty) designation recognizes a BICSI member’s proficiency in NTS
and internetworking design.
•
The Outside Plant (OSP) Specialty (RCDD/OSP Specialty) designation recognizes a
BICSI member’s proficiency in OSP design.
•
The Wireless Design Specialty (RCDD/WD Specialty) designation recognizes a BICSI
member’s proficiency in wireless design.
•
The Registered Cabling Installers and Technicians demonstrate their proficiency in
conducting site surveys, pulling cable, and terminating and testing copper and optical fiber
cable to the highest level of specification.
Training
BICSI presents leading-edge technical training in all phases of ITS distribution design and
installation. These vendor-neutral courses are offered at hundreds of locations across the
country and around the world, including almost 100 BICSI Authorized Training Facilities (ATFs).
In addition, BICSI can bring its first-class training to your location. All BICSI courses are
available for on-site training. BICSI also offers a number of online courses.
BICSI members gain knowledge and continuing education credits (CECs) by attending BICSI
courses and conferences and classes.
Educational Conferences
Each year, BICSI hosts design conferences in North America, as well as regularly scheduled
conferences held in other BICSI Districts and Regions worldwide. Conferences include
presentations by leaders in the ITS industry and opportunities to network with your peers.
© 2007 BICSI®
ix
OSP Design Reference Manual, 4th edition
Member Benefits, continued
Technical Publications
Become a member and you will receive substantial discounts on BICSI’s highly acclaimed
manuals—long considered the definitive reference source of the industry. BICSI’s manuals
serve as valuable reference tools and detailed study guides for BICSI courses and exams.
Also available on CD-ROM, BICSI manuals are now based on global best practices that
follow and, in many cases, exceed the requirements of recognized international codes,
standards, and regulations. Our most popular publications include the Telecommunications
Distribution Methods Manual (TDMM), Network Design Reference Manual (NDRM),
Electronic Safety and Security Design Reference Manual (ESSDRM), Outside Plant
Design Reference Manual (OSPDRM), Information Transport Systems Installation
Manual (ITSIM), Wireless Design Reference Manual (WDRM), Residential Network
Cabling Manual (RNCM), AV Design Reference Manual (AVDRM) [a joint publication
with InfoComm International®]), and BICSI Information Transport Systems (ITS)
Dictionary. BICSI publishes many workbooks to complement selected manuals.
Legislative and Standards Involvement
In the United States, the BICSI Governmental Relations Committee constantly monitors
legislative, regulatory, and judicial activities and will advise you of any actions that affect
BICSI and its membership. BICSI’s representatives take active roles in standards-setting
panels and agencies worldwide.
BICSI Community UPLINK
In an effort to reduce inbox clutter, yet still provide members with important information,
BICSI has consolidated most of its e-mails into regularly scheduled, bimonthly e-mails called
Community UPLINK. This e-communication features news about upcoming conferences,
workshops, and region meetings; calls for presentations; training and exam schedules;
announcements from the Board of Directors; new publications; and other newsworthy BICSI
information.
Recruiting and Job Search Engine
BICSI’s ITS-jobs.com offers the ITS industry an effective tool to bring employers and job
seekers together. ITS-jobs.com has an expanded number of resumes and jobs posted and
offers an important service for BICSI members and the entire ITS industry.
The Web-based resume posting, recruiting, and job search engine is truly an interactive tool.
Using ITS-jobs.com, job seekers can post, edit, and update resumes. Areas of expertise can
be identified so that employers can more easily find qualified candidates. Automatic
notifications are sent when job postings match job seeker criteria.
If you are an employer seeking ITS talent, the extensive search capabilities of ITS-jobs.com
help filter experience and background to search for the most qualified candidates. You also
will have access to statistics, such as number of views and number of applications for a job
posting.
There is no cost to post and manage resumes and apply for jobs. For posting available jobs,
employers pay a fee. A discounted rate applies to employers who are BICSI members.
Complete information can be found at www.ITS-jobs.com.
OSP Design Reference Manual, 4th edition
x
© 2007 BICSI®
Member Benefits, continued
Newsletters and Redesigned Web Site
BICSI helps keep you in touch with industry news and association activities through BICSI
News, Community UPLINK, and targeted communications. BICSI’s redesigned Web site
(www.bicsi.org) provides immediate information about BICSI activities around the world. The
site features searchable databases where members and visitors can register for courses,
conferences, and exams, participate in online forum discussion topics, verify a member’s
BICSI certifications, and view a listing of almost 10,000 BICSI Registered Installers and
Technicians. Promote your company online as a BICSI Corporate Member and include a
direct link to your Web site. Purchase manuals and receive “members-only” access to
valuable documents.
Join BICSI Today!
BICSI membership is open to individuals and corporations serving the ITS and building
industries. Join BICSI and combine your expertise with your colleagues in the network of ITS
professionals. Complete BICSI information is available upon request. For a membership
application or other information, contact:
BICSI World Headquarters
8610 Hidden River Parkway
Tampa, FL 33637-1000 USA
Tel.: 800.242.7405 (USA/Canada toll-free)
Tel.: +1 813.979.1991
Fax: +1 813.971.4311
E-mail: bicsi@bicsi.org
Web site: www.bicsi.org
© 2007 BICSI®
xi
OSP Design Reference Manual, 4th edition
OSP Design Reference Manual, 4th edition
xii
© 2007 BICSI®
Comments? More Information?
For information on how to use this manual, see the following page.
To submit comments about the BICSI Outside Plant Design Reference Manual
(OSPDRM) or for further information about BICSI, please complete the Readers
Comment Form in this section or contact:
BICSI World Headquarters
8610 Hidden River Parkway
Tampa, FL 33637-1000 USA
Tel.: 800.242.7405 (USA/Canada toll-free)
Tel.: +1 813.979.1991
Fax: +1 813.971.4311
E-mail: bicsi@bicsi.org
Web site: www.bicsi.org
© 2007 BICSI®
xiii
OSP Design Reference Manual, 4th edition
OSP Design Reference Manual, 4th edition
xiv
© 2007 BICSI®
How to Use This Manual
Chapter number and name are indicated
at the outside top of each page.
Chapter 1: Overview
Chapters are divided into sections.
Section Heading
Topic Heading
Each chapter
section is divided
into multiple
subheadings.
Part Heading
Part headings are used to discuss major areas of a topic.
•
Bullet important terms and phrases.
–
Bullets are often followed by more detailed information.
Figures, examples, and tables are numbered sequentially in a given
chapter. Each is followed by a brief descriptive title.
Figure 1.1
Title
OSP Design Reference
© 2007 BICSI®
Page numbers are
shown at the bottom
Manual, 4th edition
of the page. The
chapter number
precedes the page
number.
1-1
xv
© 2007 BICSI®
OSP Design Reference Manual, 4th edition
OSP Design Rererence Manual, 4th edition
xvi
© 2007 BICSI®
Table of Contents
Table of Contents
Chapter 1: Overview
Overview .................................................................................................... 1-1
Purpose ...................................................................................................... 1-3
Professionalism .........................................................................................
1-8
Chapter 2: Legal considerations for the OSP designer
Legal Aspects of Outside Plant (OSP) Design .................................................... 2-1
References ............................................................................................... 2-12
Chapter 3: Cable Types
Cabling ....................................................................................................... 3-1
Recognized Cable ......................................................................................... 3-3
Optical Fiber Cabling ..................................................................................... 3-5
Balanced Twisted-Pair Copper Cabling ........................................................... 3-31
Coaxial Cabling .......................................................................................... 3-68
Twinaxial Cabling ........................................................................................ 3-80
Hybrid Fiber Coaxial Cabling ......................................................................... 3-81
Appendix: Rural Utilities Service (RUS) Type Cable ........................................... 3-84
References ............................................................................................... 3-85
Chapter 4: Cabling Infrastructure
Introduction ................................................................................................ 4-1
Topology .................................................................................................... 4-3
Chapter 5: Pathways and Spaces
Route Design ............................................................................................... 5-1
Pathways ................................................................................................... 5-7
SECTION 1: UNDERGROUND PATHWAYS
Underground Pathways ................................................................................. 5-9
Tunnels .................................................................................................... 5-67
SECTION 2: DIRECT-BURIED PATHWAYS
Direct-Buried Pathways ............................................................................... 5-73
Placing Direct-Buried Cable .......................................................................... 5-77
SECTION 3: AERIAL PATHWAYS
Aerial Pathways ......................................................................................... 5-85
© 2007 BICSI®
i
OSP Design Reference Manual, 4th edition
Table of Contents
SECTION 4: AERIAL CONSTRUCTION PRACTICES
Placement .............................................................................................. 5-157
Methods of Raising and Setting Poles .......................................................... 5-173
SECTION 5: SPACES
Spaces .................................................................................................. 5-199
Handholes (HHs) ...................................................................................... 5-218
Pedestals, Cabinets, and Vaults ................................................................. 5-221
Controlled Environment Vault (CEV) ............................................................ 5-225
Concrete Universal Enclosure (CUE) ............................................................ 5-226
Marinas .................................................................................................. 5-227
References ............................................................................................. 5-234
Chapter 6: Splicing Hardware
Splicing Enclosure ........................................................................................ 6-1
References ............................................................................................... 6-33
Chapter 7: Grounding, Bonding, and Protection
Introduction ................................................................................................ 7-1
Bonding Requirements ................................................................................. 7-10
Protectors ................................................................................................ 7-25
Grounding for Lightning Protection ................................................................ 7-28
Electrical Protection in Tunnels .................................................................... 7-33
References ............................................................................................... 7-36
Chapter 8: Right-of-Way
Right-of-Way .............................................................................................. 8-1
Property Descriptions ................................................................................... 8-9
Methods of Describing Property .................................................................... 8-10
Real Estate Law ......................................................................................... 8-27
Chain of Title ............................................................................................ 8-34
Restrictions, Covenants, and Conditions ........................................................ 8-35
Liens and Encumbrances ............................................................................. 8-36
Contents of the Private Easement Document .................................................. 8-42
Permit Information ..................................................................................... 8-43
Chapter 9: Scope of Work
Statement of Work ....................................................................................... 9-1
OSP Design Reference Manual, 4th edition
ii
© 2007 BICSI®
Table of Contents
Chapter 10: Design Documentation
Construction Documents ............................................................................. 10-1
Outside Plant (OSP) Design and Construction Checklist .................................... 10-9
Chapter 11: Cost Estimating
Development of Cost Estimating ................................................................... 11-1
Outside Plant (OSP) Cost Estimating ............................................................. 11-6
Estimating the Cost of a Small Project (Example) .......................................... 11-11
Chapter 12: Maintenance and Restoration
Maintenance of Outside Plant (OSP) Facilities ................................................. 12-1
Emergency Restoration Procedures ............................................................... 12-9
Chapter 13: Special Design Considerations
Air Pressure Systems .................................................................................. 13-1
Overbuild on Existing Aerial Facilities ........................................................... 13-15
Overbuild on Existing Underground Pathways ................................................ 13-22
Extending a Cable Vault ............................................................................ 13-24
References ............................................................................................. 13-25
Appendix A: Codes, Standards, and Regulations
Overview .................................................................................................... A-1
Industry-Related Organizations ...................................................................... A-1
Publications ................................................................................................ A-4
References ................................................................................................. A-7
Bibliography and Resources
Glossary
Index
© 2007 BICSI®
iii
OSP Design Reference Manual, 4th edition
Table of Contents
Figures
Chapter 3: Cable Types
Figure 3.1
Cable sizing ........................................................................ 3-2
Figure 3.2
Duplex subscriber connector interface .................................... 3-7
Figure 3.3
Loose tube cable cross section ........................................... 3-21
Figure 3.4
Tight-buffered cables ........................................................ 3-23
Figure 3.5
Tube cable ....................................................................... 3-25
Figure 3.6
ALPETH cable ................................................................... 3-45
Figure 3.7
Self-supporting cable ......................................................... 3-47
Figure 3.8
Reinforced self-supporting cable .......................................... 3-50
Figure 3.9
PASP type design .............................................................. 3-53
Figure 3.10
Filled ASP type cable ......................................................... 3-56
Figure 3.11
Filled ALPETH type cable .................................................... 3-60
Figure 3.12
Underground (ductpic) cable ............................................... 3-62
Figure 3.13
Air core screened cable ...................................................... 3-65
Figure 3.14
Filled screened cable ......................................................... 3-66
Figure 3.15
Coaxial cable .................................................................... 3-68
Figure 3.16
Aerial coaxial cables .......................................................... 3-72
Figure 3.17
Armored cable .................................................................. 3-73
Figure 3.18
Trunk and feeder system .................................................... 3-75
Figure 3.19
Standard shield and quad shield construction (drop cable) ....... 3-76
Figure 3.20
Video link loss ................................................................... 3-79
Figure 3.21
Twinaxial cable ................................................................. 3-80
Figure 3.22
Optical fiber coaxial system ............................................... .3-81
Chapter 4: Cabling Infrastructure
Figure 4.1
Star topology ..................................................................... 4-4
Figure 4.2
Hierarchical star topology ..................................................... 4-5
Figure 4.3
Physical star/logical ring topology .......................................... 4-7
Figure 4.4
Buildings connected by a physical ring topology ....................... 4-8
Figure 4.5
Main backbone ring and redundant backbone star combined ....... 4-9
Figure 4.6
Clustered star topology with physical star/logical ring ............. 4-10
Figure 4.7
Optical fiber ring topology (simplified) ................................... 4-11
Figure 4.8
Bus topology .................................................................... 4-12
Figure 4.9
Tree and branch topology ................................................... 4-13
OSP Design Reference Manual, 4th edition
iv
© 2007 BICSI®
Table of Contents
Chapter 5: Pathways and Spaces
Figure 5.1
Lateral and subsidiary conduits ............................................ 5-16
Figure 5.2
Live or dynamic load dispersal ............................................. 5-22
Figure 5.3
Dead or earth load dispersal ................................................ 5-23
Figure 5.4
Conduit casings under railroads ........................................... 5-33
Figure 5.5
Conduit casings under highway ............................................ 5-34
Figure 5.6
Forces acting on cable pulled through straight conduit ............ 5-37
Figure 5.7
Inclined straight conduit ..................................................... 5-39
Figure 5.8
Simple bend ..................................................................... 5-40
Figure 5.9
Microduct ........................................................................ 5-50
Figure 5.10
Typical concrete-encased conduit structure .......................... 5-51
Figure 5.11
Typical compacted fill conduit structure ................................ 5-52
Figure 5.12
Typical trench shield .......................................................... 5-53
Figure 5.13
Typical trench with shoring in unstable ground ....................... 5-54
Figure 5.14
Typical trench with shoring in stable ground .......................... 5-55
Figure 5.15
Bell end conduit slip sleeve ................................................. 5-57
Figure 5.16
Expansion joints ................................................................ 5-58
Figure 5.17
Angle bracing ................................................................... 5-59
Figure 5.18
Longitudinal bracing and load forces ..................................... 5-60
Figure 5.19
Anchor and plug ................................................................ 5-61
Figure 5.20
Back-to-back expansion joint units ...................................... 5-61
Figure 5.21
Back-to back expansion joint .............................................. 5-62
Figure 5.22
In-line single-expansion joint over 30.5 m (100 ft) .................. 5-62
Figure 5.23
Expansion joint under 30.5 m (100 ft) ................................... 5-63
Figure 5.24
Single expansion joint ........................................................ 5-63
Figure 5.25
Angle bracing into stranded area ......................................... 5-64
Figure 5.26
Conduit installed in sidewalk portion of bridge ........................ 5-65
Figure 5.27
Conduit installed by hanging under sidewalk portion
of bridge .......................................................................... 5-65
Figure 5.28
Conduit run attached to side of bridge with steel brackets ...... 5-66
Figure 5.29
Conduit runs attached to steel I-beams ................................ 5-66
Figure 5.30
Typical shallow tunnel section ............................................. 5-68
Figure 5.31
Protection of direct-buried cable ......................................... 5-74
Figure 5.32
Walk behind trencher ......................................................... 5-77
Figure 5.33
Tractor-drawn trencher ...................................................... 5-78
Figure 5.34
Trencher/vibratory plow ..................................................... 5-79
Figure 5.35
Vibratory plow .................................................................. 5-79
Figure 5.36
Rip plow ........................................................................... 5-80
© 2007 BICSI®
v
OSP Design Reference Manual, 4th edition
Table of Contents
Figure 5.37
Rock saw ......................................................................... 5-80
Figure 5.38
Auger bore ....................................................................... 5-82
Figure 5.39
Horizontal directional drilling machine .................................... 5-83
Figure 5.40
Wind and ice loadings ........................................................ 5-88
Figure 5.41
Example of keying a pole .................................................. 5-101
Figure 5.42
Pole placement utilizing terrain feature ............................... 5-110
Figure 5.43
Slack span ..................................................................... 5-118
Figure 5.44
Building attachment methods ............................................ 5-119
Figure 5.45
Flying cross .................................................................... 5-120
Figure 5.46
Midspan clearances ......................................................... 5-122
Figure 5.47
Vertical clearances over obstacles ..................................... 5-123
Figure 5.48
Vertical clearances between utilities ................................... 5-124
Figure 5.49
Clearance distances ........................................................ 5-126
Figure 5.50
Push brace ..................................................................... 5-129
Figure 5.51
Guying configurations ....................................................... 5-130
Figure 5.52
Storm Guying .................................................................. 5-131
Figure 5.53
Definition of lead and height ............................................. 5-132
Figure 5.54
Calculating pull with pull finder .......................................... 5-133
Figure 5.55
Calculating pull with tape measure ..................................... 5-134
Figure 5.56
Guy rule ......................................................................... 5-138
Figure 5.57
Using guy strand selection chart example ............................ 5-139
Figure 5.58
Types of common anchors ................................................ 5-140
Figure 5.59
Guy rod ends .................................................................. 5-144
Figure 5.60
Aerial to underground transition ......................................... 5-152
Figure 5.61
Aerial to direct-buried transition ........................................ 5-152
Figure 5.62
Underground to direct-buried transition .............................. 5-153
Figure 5.63
Underground to building transition ...................................... 5-153
Figure 5.64
Aerial to building transition ................................................ 5-154
Figure 5.65
Direct-buried to building transition ..................................... 5-155
Figure 5.66
Typical settings of poles in permafrost ................................ 5-162
Figure 5.67
Effect on pole when active layer above permafrost
is refrozen ...................................................................... 5-163
Figure 5.68
Setting pole in sloping ground ........................................... 5-165
Figure 5.69
Typical pole crib .............................................................. 5-166
Figure 5.70
Digging pole hole with hand tools ....................................... 5-169
Figure 5.71
Digging pole hole with a water jet ...................................... 5-172
Figure 5.72
Setting pole using A-frame line truck .................................. 5-174
Figure 5.73
Sighting pole to ensure it is level and plumb ........................ 5-175
Figure 5.74
Raising pole using manpower, pole pikes,
and a deadman pole support ............................................. 5-178
OSP Design Reference Manual, 4th edition
vi
© 2007 BICSI®
Table of Contents
Figure 5.75
Raking pole prior to tamping .............................................. 5-180
Figure 5.76
Plank footing for pole ....................................................... 5-181
Figure 5.77
Plank footing and catenary design ..................................... 5-182
Figure 5.78
Plank and log footing and catenary design ........................... 5-183
Figure 5.79
Platform support ............................................................. 5-184
Figure 5.80
Side guys and platform support ......................................... 5-185
Figure 5.81
Platform support at H fixture ............................................. 5-186
Figure 5.82
Log ground brace ............................................................ 5-188
Figure 5.83
Measuring for push brace ................................................. 5-191
Figure 5.84
Push brace on single pole ................................................. 5-193
Figure 5.85
Push brace on H fixture .................................................... 5-194
Figure 5.86
Double push brace ........................................................... 5-195
Figure 5.87
Push-pull brace ............................................................... 5-197
Figure 5.88
Typical maintenance hole (cutaway side view) ..................... 5-201
Figure 5.89
Maintenance hole diagram ................................................ 5-202
Figure 5.90
Maintenance hole frame, cover, and collar ........................... 5-203
Figure 5.91
Center conduit tray ......................................................... 5-204
Figure 5.92
Splayed conduit entry ...................................................... 5-204
Figure 5.93
Basic A precast maintenance hole ...................................... 5-205
Figure 5.94
Type A maintenance hole with center conduit window
(plan view) .................................................................... 5-210
Figure 5.95
Type A maintenance hole with splayed window
(plan view) .................................................................... 5-210
Figure 5.96
Type J maintenance hole with center conduit window
(plan view) .................................................................... 5-211
Figure 5.97
Type J maintenance hole with splayed conduit windows
(plan view) .................................................................... 5-211
Figure 5.98
Type L maintenance hole with center conduit window
(plan view) .................................................................... 5-212
Figure 5.99
Type L maintenance hole with splayed conduit window
(plan view) .................................................................... 5-212
Figure 5.100
Type T maintenance hole with center conduit window
(plan view) .................................................................... 5-213
Figure 5.101
Type T maintenance hole with splayed conduit window
(plan view) .................................................................... 5-213
Figure 5.102
Typical cable maintenance hole ......................................... 5-214
Figure 5.103
Typical handhole ............................................................. 5-219
Figure 5.104
Pedestals and cabinets .................................................... 5-224
Figure 5.105
Modular floating dock layout ............................................. 5-231
Figure 5.106
Sample marina layout ....................................................... 5-233
© 2007 BICSI®
vii
OSP Design Reference Manual, 4th edition
Table of Contents
Chapter 6: Splicing Hardware
Figure 6.1
Splice closures and covers .................................................... 6-2
Figure 6.2
Splice closures .................................................................... 6-3
Figure 6.3
Filled/direct-buried splice closure systems ............................... 6-6
Figure 6.4
Optical fiber closure ............................................................. 6-7
Figure 6.5
Underground to building transition ........................................ 6-10
Figure 6.6
Underground to direct-buried transition ................................ 6-11
Figure 6.7
Direct-buried to building transition ....................................... 6-12
Figure 6.8
Example of IDC connection ................................................. 6-15
Figure 6.9
Types of splices ................................................................ 6-15
Figure 6.10
Example of single pair splice connectors and modules .............. 6-16
Figure 6.11
Example of multipair splice connectors and modules ................ 6-17
Figure 6.12
Inline splice ...................................................................... 6-18
Figure 6.13
Foldback splice ................................................................. 6-19
Figure 6.14
Completed two-bank splice ................................................. 6-19
Figure 6.15
Examples of splices required due to cable routing ................... 6-26
Figure 6.16
Splice tray examples .......................................................... 6-31
Chapter 7: Grounding (Earthing), Bonding, and Protection
Figure 7.1
Ground potential rise ............................................................ 7-4
Figure 7.2
Multiground neutral power system .......................................... 7-6
Figure 7.3
Non-multiground neutral power system ................................... 7-7
Figure 7.4
Wye power system .............................................................. 7-8
Figure 7.5
Delta power system ............................................................. 7-9
Figure 7.6
Ground connection on a pole (multiground neutral system) ...... 7-12
Figure 7.7
Grounding (earthing) without access to transformers .............. 7-15
Figure 7.8
Welded bonding attachment to rebar for site-poured
maintenance hole .............................................................. 7-17
Figure 7.9
Clamped bonding attachment to rebar for precast or
site-poured maintenance hole ............................................. 7-18
Figure 7.10
Interior grounding (earthing) and bonding for racking .............. 7-18
Figure 7.11
Underground cable bonding ................................................. 7-19
Figure 7.12
Maintenance hole bonding .................................................. 7-20
Figure 7.13
Isolation gap .................................................................... 7-23
Chapter 8: Right-of-Way
Figure 8.1
Method of township numbering ............................................ 8-11
Figure 8.2
Theoretical township numbering ........................................... 8-12
Figure 8.3
Section subdivision ............................................................ 8-14
OSP Design Reference Manual, 4th edition
viii
© 2007 BICSI®
Table of Contents
Figure 8.4
Small subdivision ............................................................... 8-15
Figure 8.5
Legal subdivision and lotting ............................................... 8-16
Figure 8.6
State coordinate system .................................................... 8-18
Figure 8.7
Use of the protractor ......................................................... 8-19
Figure 8.8
Naming conventions for metes and bounds ............................ 8-21
Figure 8.9
Metes and bounds ............................................................. 8-22
Figure 8.10
Subdivision plat and description ........................................... 8-23
Figure 8.11
Centerline description ........................................................ 8-24
Figure 8.12
Point description ............................................................... 8-25
Figure 8.13
Associated construction drawing for state permit application ... 8-45
Figure 8.14
Casing lengths for various railroad crossing angles .................. 8-48
Figure 8.15
Layout of a railroad crossing ............................................... 8-49
Figure 8.16
Arrangements for different casing sizes ................................ 8-52
Chapter 10: Design Documentation
Figure 10.1
Splicing together two sections of same cable ...................... 10-23
Figure 10.2
Splicing a shorted cable order ........................................... 10-23
Figure 10.3
Splicing two cables of different sizes .................................. 10-24
Figure 10.4
Splicing a new branch cable to a feed cable ........................ 10-24
Figure 10.5
New cables and a terminal spliced ...................................... 10-25
Figure 10.6
Cross-connect cabinet terminating gel-filled cables .............. 10-25
Figure 10.7
Removal of NF-16 terminal ................................................ 10-26
Figure 10.8
Replacing an NF-16 terminal with an NF-25 terminal .............. 10-26
Figure 10.9
Energizing dead pairs ....................................................... 10-27
Figure 10.10
Remove cross-connect terminal ......................................... 10-27
Figure 10.11
200-Pair cable transfer at splice ........................................ 10-28
Figure 10.12
300-Pair cable transfer to new feeder cable ........................ 10-28
Figure 10.13
Section replacement on 300-pair cable ............................... 10-29
Figure 10.14
Protector placement ........................................................ 10-29
Figure 10.15
Sample maintenance hole plan and profile drawing ................ 10-30
Figure 10.16
Butterfly detail worksheet ................................................. 10-31
Figure 10.17
Butterfly detail ................................................................ 10-32
Chapter 11: Cost Estimating
Figure 11.1
New construction proposal to ABC corporate office .............. 11-11
Chapter 13: Special Design Considerations
Figure 13.1
Air dryer .......................................................................... 13-3
Figure 13.2
Manifold assembly and shutoff valve .................................... 13-4
Figure 13.3
Transducer housing mounted on framing channels ................... 13-5
© 2007 BICSI®
ix
OSP Design Reference Manual, 4th edition
Table of Contents
Figure 13.4
Example of pressure transducer installation ........................... 13-6
Figure 13.5
Flow transducer ................................................................ 13-7
Figure 13.6
Typical air pressure schematic design ................................... 13-9
Figure 13.7
Typical schematic of air pressure system ............................ 13-11
Figure 13.8
Example of buried cable leaving underground ....................... 13-12
Figure 13.9
Underground to aerial interface ......................................... 13-13
Figure 13.10
Buffering arrangement at a splice ...................................... 13-14
Figure 13.11
Typical pole space allocations ........................................... 13-17
Tables
Chapter 3: Cable Types
Table 3.1
Optical fiber cable performance by type .................................. 3-6
Table 3.2
Calculating the optical fiber attenuation margin ........................ 3-8
Table 3.3
Calculating losses .............................................................. 3-12
Table 3.4
Splice loss values in decibels ............................................... 3-13
Table 3.5
System gain, power penalties, and the link loss
budget calculations ........................................................... 3-14
Table 3.6
Minimum system loss .......................................................... 3-16
Table 3.7
Supportable distances and channel insertion loss for
optical fiber applications by optical fiber type ........................ 3-17
Table 3.8
Supportable distances and channel insertion loss for
optical fiber applications by fiber type .................................. 3-19
Table 3.9
Example of color coding—individual optical fibers .................... 3-30
Table 3.10
Loop gauging table ............................................................ 3-32
Table 3.11
Cable transmission characteristics ....................................... 3-33
Table 3.12
Insulation types ................................................................ 3-35
Table 3.13
Cable composition types ..................................................... 3-36
Table 3.14
Cable sheath compositions .................................................. 3-40
Table 3.15
Cable usage guide ............................................................. 3-42
Table 3.16
Common color code ........................................................... 3-44
Table 3.17
ALPETH cable ................................................................... 3-46
Table 3.18
Self-supporting cable ......................................................... 3-48
Table 3.19
Reinforced self-supporting cable .......................................... 3-51
Table 3.20
PASP cables ..................................................................... 3-54
OSP Design Reference Manual, 4th edition
x
© 2007 BICSI®
Table of Contents
Table 3.21
Filled ASP type cable ......................................................... 3-57
Table 3.22
PE 39—Filled solid ALPETH cable .......................................... 3-58
Table 3.23
Filled ALPETH type cable .................................................... 3-61
Table 3.24
Bonded STALPETH/ductpic cable .......................................... 3-63
Table 3.25
Cable attenuation at VSWR = 1.0, 50 ohm foam dielectric
and ambient 20 °C (68 °F) .................................................. 3-74
Table 3.26
Coaxial attenuation at 20 °C (68 °F) over long distances ........ 3-74
Table 3.27
Drop cable and attenuation ................................................. 3-76
Table 3.28
Drop cable and attenuation at maximum drop length ............... 3-77
Table 3.29
Generic impedance for video infrastructure components .......... 3-78
Table 3.30
RUS acceptance cable-coding plan ...................................... 3-84
Table 3.31
Description of codes .......................................................... 3-84
Chapter 5: Pathways and Spaces
Table 5.1
Uniform color code for utility flagging, painting, or marking ......... 5-5
Table 5.2
Domestic and international one-call locate company
telephone numbers .............................................................. 5-9
Table 5.3
Clearances ....................................................................... 5-21
Table 5.4
Conduit formations ............................................................ 5-25
Table 5.5
Straight lengths of individual conduit .................................... 5-26
Table 5.6
Rigid bends for 100 mm (4 trade size) individual conduit .......... 5-26
Table 5.7
Galvanized rigid steel conduit sizes ...................................... 5-30
Table 5.8
Coefficient of friction ......................................................... 5-36
Table 5.9
Cable pulling tension .......................................................... 5-41
Table 5.10
Cubic yards of concrete per 30.5 m (100 ft) of trench ............ 5-51
Table 5.11
Cubic yards of compacted fill per 30.5 m (100 ft) of trench ..... 5-52
Table 5.12
Minimum trench shoring requirements ................................... 5-56
Table 5.13
Ice, wind, and temperature ................................................. 5-90
Table 5.14
Pole class and transverse breaking strength .......................... 5-92
Table 5.15
Pole resistance moments .................................................... 5-94
Table 5.16
Rated fiber strength for pole species .................................... 5-94
Table 5.17
Resistance moments for various sizes of poles ....................... 5-95
Table 5.18
Pole setting depth required for various heights ....................... 5-99
Table 5.19
Transverse load on pole (kg/m per lb/ft of span length) ......... 5-103
Table 5.20
Load imposed by pole attachment ...................................... 5-105
Table 5.21
Minimum pole class to support vertical load ......................... 5-108
Table 5.22
Maximum span lengths for self-supporting cable ................... 5-111
Table 5.23
Pole span length/tension .................................................. 5-112
© 2007 BICSI®
xi
OSP Design Reference Manual, 4th edition
Table of Contents
Table 5.24
Weight for ALPETH cable .................................................. 5-113
Table 5.25
Cable weight for self-supporting cable ................................ 5-115
Table 5.26
Cable weight for self-supporting cable reinforced sheath ....... 5-116
Table 5.27
Typical attachment clearances .......................................... 5-121
Table 5.28
Minimum vertical clearances of cables above ground or
rails at midspan crossing .................................................. 5-125
Table 5.29
Minimum vertical clearance of cable runs along and
within limits of public highways .......................................... 5-125
Table 5.30
Strand sizes ................................................................... 5-127
Table 5.31
Calculating pull when angle is known .................................. 5-135
Table 5.32
Minimum allowable tension for guys .................................... 5-136
Table 5.33
Minimum guy strand selection table .................................... 5-137
Table 5.34
Guy strand selection table ................................................ 5-139
Table 5.35
Anchor groupings ............................................................ 5-142
Table 5.36
Soil classifications ........................................................... 5-146
Table 5.37
Anchor types recommended for different soil classes ............ 5-147
Table 5.38
Grades of construction for communications conductors ......... 5-150
Table 5.39
Standard pole settings ..................................................... 5-158
Table 5.40
Pole settings for solid rock below surface level ..................... 5-159
Table 5.41
Lengths of pole braces ..................................................... 5-190
Table 5.42
Maintenance hole ratings .................................................. 5-200
Table 5.43
Maintenance hole window selection .................................... 5-208
Table 5.44
Maintenance hole frames and covers .................................. 5-216
Table 5.45
Precabling guidelines ........................................................ 5-228
Chapter 6: Splicing Hardware
Table 6.1
Aerial closure size ............................................................... 6-5
Table 6.2
Direct-buried/underground closure size ................................... 6-7
Table 6.3
Two-bank fold-back splice data ........................................... 6-20
Table 6.4
26 AWG two-bank straight splice ......................................... 6-21
Table 6.5
26 AWG three-bank straight splice ....................................... 6-22
Table 6.6
26 AWG four-bank straight splice ......................................... 6-23
Table 6.7
26 AWG two-bank apparatus splice ...................................... 6-24
Chapter 8: Right-of-Way
Table 8.1
Specifications for steel casing ............................................. 8-54
Chapter 10: Design Documentation
Table 10.1
Construction document specifications process ....................... 10-8
Table 10.2
Outside plant design checklist ........................................... 10-10
Table 10.3
Outside plant construction specifications checklist ............... 10-17
OSP Design Reference Manual, 4th edition
xii
© 2007 BICSI®
Table of Contents
Chapter 11: Cost Estimating
Table 11.1
Matrix for estimating costs ............................................... 11-14
Chapter 12: Maintenance and Restoration
Table 12.1
Routing maintenance checklist ............................................ 12-4
Table 12.2
Demand maintenance ......................................................... 12-8
Table 12.3
Emergency restoration issues ............................................ 12-11
Chapter 13: Special Design Considerations
Table 13.1
Typical minimum pressure ................................................... 13-8
Examples
Chapter 3: Cable Types
Example 3.1
Optical fiber attenuation margin calculations worksheet ............ 3-9
Chapter 5: Pathways and Spaces
Example 5.1
Tension worksheet form ..................................................... 5-43
Example 5.2
Conduit run layout ............................................................. 5-44
Example 5.3
Worksheet A to B (imperial and metric) ................................. 5-46
Example 5.4
Worksheet B to A (imperial and metric) ................................. 5-47
Chapter 8: Right-of-Way
Example 8.1
© 2007 BICSI®
Typical state permit application ........................................... 8-44
xiii
OSP Design Reference Manual, 4th edition
Table of Contents
OSP Design Reference Manual, 4th edition
xiv
© 2007 BICSI®
Chapter 1
Overview
Chapter 1 defines the roles and responsibilities of an
outside plant (OSP) designer. It identifies the purpose of
standardization, planning, and work prints in OSP design.
Overviews of right-of-way (R/W), cabling, and air pressure
systems in OSP design are provided. The meaning and
scope of professionalism also are briefly explained.
Chapter 1: Overview
Table of Contents
Overview ............................................................................................ 1-1
Definition .................................................................................................... 1-1
Introduction ................................................................................................ 1-1
Purpose .............................................................................................. 1-3
Introduction ................................................................................................ 1-3
Standardization ........................................................................................... 1-3
Codes, Standards, and Methodology ............................................................... 1-4
Purpose of Codes and Standards .................................................................... 1-4
Planning ..................................................................................................... 1-5
Work Prints ................................................................................................. 1-5
Right-of-Way (R/W) ..................................................................................... 1-6
Pathways and Spaces .................................................................................. 1-6
Cabling ....................................................................................................... 1-7
Air-Pressure Systems ................................................................................... 1-7
Professionalism .................................................................................. 1-8
Introduction ................................................................................................ 1-8
Industry-Related Organizations ...................................................................... 1-8
Other Valuable Sources ................................................................................. 1-9
© 2007 BICSI®
1-i
OSP Design Reference Manual, 4th edition
Chapter 1: Overview
OSP Design Reference Manual, 4th edition
1-ii
© 2007 BICSI®
Chapter 1: Overview
Overview
BICSI strongly advises the readership of this manual to heed the following warning.
WARNING:
It is the responsibility of the user of this manual to determine and use the
applicable local safety and health practices associated with outside plant
(OSP). OSP is inherently dangerous. BICSI shall not be liable to the
purchaser or any other entity with respect to any liability, loss, or damage
caused directly or indirectly by the application or use of this manual. No
project is so important, or completion deadline so critical, to justify
nonconformance with industry standards. This manual does not address
safety issues associated with its use. It is the designer’s responsibility to use
established and appropriate safety and health practices and to determine the
applicability of all regulatory agencies.
Definition
BICSI defines OSP as the telecommunications infrastructure designed for installation exterior
to buildings and typically routed into the entrance facility (EF).
OSP may include:
•
Balanced twisted-pair cabling.
•
75 ohm coaxial cabling.
•
Optical fiber cabling.
•
Supporting structures required to link serving facilities to outlying locations to provide for
voice, data, video, and other low-voltage systems.
Introduction
OSP became a requirement with the placement of a first telegraph system. It consisted of a
wire or a pair of wires linking two stations. From this simple beginning, OSP has expanded into
a vast global telecommunications infrastructure.
OSP facilities are designed, installed, and maintained by local access providers (APs) serving
specific geographic areas. OSP facilities located on private properties or in areas not covered
by a local AP become the customer’s responsibility. Private companies offer OSP design,
engineering, and construction and augment the construction forces of local APs.
In some countries, the AP (i.e., the provider of the physical connection) is also the service
provider (SP [i.e., the provider of the desired service]) and can be the same company.
© 2007 BICSI®
1-1
OSP Design Reference Manual, 4th edition
Chapter 1: Overview
Introduction, continued
Telecommunications deregulation gives independent contractors access to OSP contracts and
creates opportunities for qualified information transport systems (ITS) distribution designers in
today’s open and competitive market.
The designer is responsible for designing not only the intrabuilding infrastructure but also the
interbuilding infrastructure. The designer should have knowledge of the following OSP
aspects:
•
Pathways and spaces
•
Cabling (i.e., cable and connecting hardware)
•
Grounding and bonding
•
Right-of-way (R/W)
•
System documentation
•
Codes and standards
OSP Design Reference Manual, 4th edition
1-2
© 2007 BICSI®
Chapter 1: Overview
Purpose
Introduction
Advances in technology and high levels of technical expertise in all of the aspects of the ITS
industry have increased the importance of training. Based on current standards for OSP
network design, the methodology presented in this manual provides a useful reference to the
end users seeking design assistance or training.
Standardization
OSP networks may differ due to:
•
Topography.
•
Climate.
•
Choice of cabling.
•
Economics.
•
Local code requirements.
•
Network functionality.
•
Current and future types of supported equipment.
•
Customer requirements.
The specifics of telecommunications infrastructure may be unique; however, overall OSP
network components and methods used to complete and maintain installations are relatively
standard. Standardizing cabling installations is necessary to ensure successful performance of
increasingly complex arrangements.
Standards are beneficial because they:
© 2007 BICSI®
•
Promote design and installation consistency.
•
Impose conformance to physical and transmission line requirements.
•
Provide a structured telecommunications facility that enables efficient system expansion
and other changes.
•
Provide for uniform documentation.
1-3
OSP Design Reference Manual, 4th edition
Chapter 1: Overview
Codes, Standards, and Methodology
Building codes and standards regulate construction in most of the world. Codes and standards
encompass most aspects of the construction industry. Codes are normally enforced by a local
agency.
While codes address minimum safety requirements, standards are intended to ensure system
performance by providing installation requirements and guidelines. Installation methods,
materials, and electrical products must conform to local code requirements.
The use of the terms shall and should in standards affects the way the stated tasks are
accomplished. These terms are defined as:
•
Shall—A mandatory requirement.
•
Should—A recommendation.
Methodology is the implementation of practices and procedures employed by a particular
industry. Installation manuals are examples of methodology.
Purpose of Codes and Standards
Building codes and standards govern installation practices and materials used when
constructing facilities.
The purpose of codes is to protect life, health, and property. The purpose of standards is to
ensure construction quality.
In general, standards are established as a basis to compare, measure, or judge:
•
Capacity.
•
Quantity.
•
Content.
•
Extent.
•
Value.
•
Quality.
Independent organizations specialize in establishing, certifying, and maintaining these codes
and standards.
OSP Design Reference Manual, 4th edition
1-4
© 2007 BICSI®
Chapter 1: Overview
Planning
Planning the construction of an OSP network may require:
•
Completing a needs assessment.
•
Determining the capacity of an existing network.
•
Calculating transmission requirements.
•
Coordinating with APs, local authorities, and utility companies.
•
Ensuring compliance with safety regulations and practices.
•
Determining the need for R/W.
•
Selecting the physical topology.
•
Selecting a route.
•
Selecting the desired cable type.
•
Preparing and sending a request for information (RFI) and evaluating the responses.
Work Prints
After making planning decisions, construction drawings and specifications must be generated.
They typically consist of:
•
A plan view of the area showing obstacles, control points, and other utilities.
•
Notification of known hazardous conditions.
•
Measurements for facility placement.
•
R/W limits.
•
Support structures, including:
•
•
© 2007 BICSI®
–
Conduit sizes and profile views of proposed routing.
–
Maintenance holes (MHs).
–
Handholes (HHs).
–
Poles, support strands, and guying information.
Media, including:
–
Cable sizes, types, and gauges.
–
Cable identification and pair/strand counts.
–
Direction of cable placement.
–
Reel identifications for cables.
Protection, including:
–
Overvoltage and overcurrent protection systems.
–
Grounding and bonding plans.
1-5
OSP Design Reference Manual, 4th edition
Chapter 1: Overview
Right-of-Way (R/W)
If an OSP network is going to extend beyond the property owned or controlled by the
customer:
•
Leased lines from the AP may be obtainable.
•
A franchise may be purchased.
•
The need for R/W arises.
To continue an OSP network outside the boundaries of a customer’s property, the customer
must either buy the strip of land or obtain written permission:
•
To attach to a utility provider’s pole line.
•
To use a utility provider’s conduit.
•
From the authority having jurisdiction (AHJ) to use public R/W or other AP or utility
easements.
•
From a private party to use their land.
Pathways and Spaces
The basic types of OSP pathways and spaces are:
•
Aerial.
•
Underground.
•
Direct-buried.
Aerial pathways and spaces consist of:
•
Poles.
•
Support strands (i.e., messengers).
•
Anchors.
•
Guys.
Underground pathways and spaces consist of:
•
Conduit.
•
MHs.
•
HHs.
•
Utility tunnels.
•
Pedestals and cabinets.
•
Vaults.
Direct-buried pathways and spaces consist of:
•
Trenches for direct-buried cable.
•
Pedestals and cabinets.
All of these pathways and spaces may be involved when installing wireless components
(e.g., towers, masts, support structures).
NOTE:
Refer to Chapter 13: Special Design Considerations. Also see the latest edition of
BICSI’s Wireless Design Reference Manual for more information.
OSP Design Reference Manual, 4th edition
1-6
© 2007 BICSI®
Chapter 1: Overview
Cabling
Cable selection depends on the customer’s needs. OSP cabling can consist of one or more of
the following cables:
•
Balanced twisted-pair
•
Coaxial
•
Optical fiber
OSP cables are specifically designed for one or more of the following installation types:
•
Aerial (e.g., lashed or self-supporting)
•
Direct-buried
•
Underground
Air Pressure Systems
Air pressure systems positively pressurize backbone cables in OSP networks to prevent
moisture from entering cables. Air pressure systems can be provided from:
•
The property owner’s main EF.
•
Remote compressor dehydrators.
•
Remote air tanks.
Typically, air pressure systems are used when air-core OSP cables are installed as directburied, underground, or aerial cables.
NOTE:
© 2007 BICSI®
The need for air pressure systems may be mitigated through alternate system
design and use of cables and cabling hardware that are appropriate for the environment. Where practicable, OSP designs that require air pressure systems should be
avoided due to high maintenance cost. Many legacy systems are being removed as
new designs and construction are established.
1-7
OSP Design Reference Manual, 4th edition
Chapter 1: Overview
Professionalism
Introduction
Keeping up with professional developments requires a designer’s commitment. A competent
designer must possess both management and business skills to be able to monitor the design
and construction of an OSP project. Some of the items that should be considered are
addressed below.
Industry-Related Organizations
To stay current, a designer should maintain a membership or certification in one or more
industry-related organizations. Following is a partial list of national and international
organizations involved in the OSP portion of telecommunications:
•
American Association of State Highway and Transportation Officials (AASHTO)
•
American National Standards Institute (ANSI)
•
BICSI®
•
Comité Européen de Normalisation Electrotechnique (European Committee for
Electrotechnical Standardization [CENELEC])
•
Institute of Electrical and Electronics Engineers, Inc.® (IEEE®)
•
Insulated Cable Engineers Association, Inc. (ICEA)
•
International Organization for Standardization/International Electrotechnical
Commission (ISO/IEC)
•
International Telecommunication Union (ITU)
•
National Fire Protection Association (NFPA)
•
Occupational Safety and Health Administration (OSHA)
•
Society of Cable Telecommunications Engineers, Inc. (SCTE)
•
Telecommunications Industry Association (TIA)
A description of these organizations is included in Appendix A.
OSP Design Reference Manual, 4th edition
1-8
© 2007 BICSI®
Chapter 1: Overview
Other Valuable Sources
The Internet is also a valuable source of real time information. The designer can research
topics of particular interest and sign up for online services that periodically send updated
information to the designer’s e-mail address.
Many training companies specialize in continuing education for telecommunications. Designers
can take advantage of training courses to stay current or to expand their knowledge of the
ITS industry.
Attending professional meetings and conferences is a valuable networking tool that allows the
designer to learn about the latest changes in the industry and to meet others with the same
concerns.
Governmental regulations affect the designer’s work. A designer can stay well informed and,
particularly, learn about changes in regulations by reading articles in periodicals or accessing
the government’s Web sites. By understanding all of the available options, the designer can
provide the customer with the optimum system available.
© 2007 BICSI®
1-9
OSP Design Reference Manual, 4th edition
Chapter 2
Legal Considerations
for the OSP Designer
Chapter 2 describes outside plant (OSP) designer roles in
the context of laws and regulations. It explains the effects of
liability and limiting legal costs through the use of alternative
dispute resolution, mediation, and arbitration.
Chapter 2: Legal Considerations for the OSP Designer
Table of Contents
Legal Aspects of Outside Plant (OSP) Design ..................................... 2-1
Design Professional’s Environment ................................................................... 2-1
Basis for Liability .......................................................................................... 2-1
Legal Issues ................................................................................................ 2-3
General Duties of Outside Plant (OSP) Designer ............................................ 2-3
Liability in Contract ................................................................................. 2-4
Liability in Tort—Secondary Liability ........................................................... 2-5
Limiting Legal Costs ...................................................................................... 2-8
Alternative Dispute Resolution ................................................................... 2-8
Mediation .............................................................................................. 2-9
Arbitration ............................................................................................. 2-9
Limiting the Design Professional’s Liability ....................................................... 2-10
References ....................................................................................... 2-12
© 2007 BICSI®
2-i
OSP Design Reference Manual, 4th edition
Chapter 2: Legal Considerations for the OSP Designer
OSP Design Reference Manual, 4th edition
2-ii
© 2007 BICSI®
Chapter 2: Legal Considerations for the OSP Designer
Legal Aspects of Outside Plant (OSP) Design
Design Professional’s Environment
The designers of any structure or system face a real threat of legal action or claim on every
project they undertake.
The outside plant (OSP) design may be completed by:
•
Architects.
•
Engineers.
•
Consultants.
•
Employees of the owner.
•
Installers (in some cases).
Of these five roles, the installer spends the most time in the field.
The OSP designer’s job can include providing the client with a complete set of documents for
an information transport systems (ITS) infrastructure that will meet the client’s performance
requirements and budget. The OSP designer’s work can be limited to technical advice or
consulting, but often will contain plans, specifications, bill of materials, installation plan, and
cost analysis.
OSP designers typically engage in some form of preliminary onsite survey or inspection. This
is necessary because a designed or recommended system must take into account the
environmental constraints in which the OSP ITS infrastructure will be installed and operated.
This would include consideration of the appropriate safeguards that may be necessary
because of the layout of a particular area, environment, topography, climate, current and
future types of equipment to be supported, type of cable, functionality of the network, and
pathway or space over which the cable will travel.
Basis for Liability
As a general principle, liability is determined on the basis of an objective standard. This is very
often guided by an industry or professional standard. Courts are likely to interpret contracts or
determine liability in negligence on the basis of the acceptable standard within the industry or
profession.
The OSP designer’s liability is defined by the published industry and norms. Norms may be the
most problematic of the three. Norms are dynamic and usually arise in trade usage or trade
custom as opposed to the standards and codes, which may have the same purpose as norms
but may be less specific than norms.
© 2007 BICSI®
2-1
OSP Design Reference Manual, 4th edition
Chapter 2: Legal Considerations for the OSP Designer
Basis for Liability, continued
The following definitions convey the general meaning of standards, codes, and norms:
•
Standards are a set of minimum requirements established by a standards development
organization (e.g., American National Standards Institute [ANSI] International Standards
Organization [ISO]).
•
Codes are rules specified by governmental entities. Consequently, codes are usually
enforceable by governmental entities. These would include local building and safety codes
as an example.
•
Norms may transcend state and professional regulations and may represent the informal
practices adopted by a particular discipline that are so prevalent that OSP designers may
be expected to have knowledge of and adhere to them.
Sometimes codes and standards are governed by the same organization as others but they are
separately administered. Nevertheless, failure to adhere to these standards, codes, and norms
give rise to legal liability. The designer should recognize that each case will vary according to
its facts and environment. A court has the authority to decide whether a particular standard,
code, or norm, while applicable in one context, is irrelevant in another. Therefore, design
professionals should use all of the available legal means to protect themselves from liability as
early in the project as possible and set a suitable context and environment in which the work
will be performed.
In addition to the standards, codes and norms, the social environment may also impact the
liability exposure of design professionals. Recently, there has been a proliferation of claims
against design professionals with courts being willing to ignore privity requirements and find
design professionals liable to third parties for their actions or omissions. Privity is a legal
principle that is peculiar to contract law. It means that only the parties to the contract are able
to sue and be sued. This chapter will examine some of the legal issues relevant to the finding
and avoidance of liability.
The OSP designer has an additional consideration which is not necessarily associated with
other designers. This is because as the name suggests, most of the design is outside of a
building or structure. This may require extension beyond the boundaries of the customer’s
property. When this happens or is likely to occur, it is important that the designer clearly define
which party has the responsibility to obtain the required permission:
•
To attach to a utility provider’s pole.
•
To use a utility provider’s conduit.
•
From the authority having jurisdiction (AHJ) to use public right-of-way (R/W) or other
access provider (AP) utility easements.
•
From a private party to use their land.
Responsibility could be assigned to the OSP designer, the owner, the installer, or some other
party responsible for obtaining necessary permission. This is necessary because liability can
be incurred by failure to obtain the requisite permissions. The owner could face liability in
trespass to land or airspace, which would be a cost that the designer had not anticipated. This
liability is different from liability in contract or negligence, which is the main focus of this
chapter. It is a liability to a third party for interference with property as opposed to a liability
from for injury or loss resulting from faulty installations or failure to follow specifications.
OSP Design Reference Manual, 4th edition
2-2
© 2007 BICSI®
Chapter 2: Legal Considerations for the OSP Designer
Legal Issues
General Duties of Outside Plant (OSP) Designer
Like all professionals, OSP designers are required to exercise due care and skill in carrying
out their discipline. To reiterate the statement previously made in this chapter, the parameters
within which the duty is optimally exercised are determined by the environment and context in
which the design professional works. The OSP designer’s environment is typically exterior to
buildings. The risks associated with the OSP designer’s job are affected by this environment.
They may arise because of physical impediments caused by the installation, or from causing
loss to customers as a result of the consultant’s failure to obtain an easement or R/W prior to
installation, or where dangerous conditions exist due to negligent or faulty installation.
With this appreciation comes the single most important duty of an OSP design professional—a
duty to engage in risk assessment and management. The methods of risk assessment and
management figure prominently in any determination of legal liability. The assessor must
determine what the public’s expectation of a design professional is and against what standards
those expectations will be measured. In such context, contracts can best assist the design
professional in avoiding, or at least minimizing, the primary liability. An equally important issue
is how the design professional may avoid secondary liability.
The design professional may be found primarily or secondarily liable in the tort of negligence
for any loss or damage resulting from a faulty design. The design professional has a number
of duties related to this issue. The design professional must have the basic technical
competency acquired through formal education, in-service training or on-the-job experience,
certifications/designations/registrations, and the knowledge of current developments in the
discipline. Yielding to the professional skills of other persons (e.g., scientific, financial,
business, and legal professionals) as required is also important.
Many professional liability claims stem from nontechnical aspects of design practice—the
acceptance of onerous contract terms and conditions, poor communication, careless selection
of projects, failure to engage in risk assessment and management, failure to record all
significant decisions and changes, and lax fee-collection practices.
The design professional has a duty to know, observe, and maintain the rules of professional
conduct that apply to the profession. In the case of a licensed professional, these rules are
generally regulated or enforced by a licensing agency. The licensing agency typically has the
power to admonish, censure, suspend, or terminate license or membership.
Regulations and codes are discussed in detail in Appendix A: Codes, Standards, and
Regulations and are not the subject of this chapter. However, they are extremely important in
the context of liability because they can form the basis of disciplinary action, with remedies
ranging from fines or suspensions to license revocations.
Courts are entitled to consider regulations and codes in determining whether particular
contractual stipulations are fair and reasonable and whether a particular faulty design was
caused by the designer’s negligence.
© 2007 BICSI®
2-3
OSP Design Reference Manual, 4th edition
Chapter 2: Legal Considerations for the OSP Designer
Legal Issues, continued
Negligence is usually determined by referring to the design professional’s general duty to
ensure public safety and welfare, whether on public or private property. This is an area in
which the standards, codes, and norms interact with the general law insofar as these rules
form a part of the body of law that courts may consider in making a decision on liability.
Liability in Contract
Liability in contract may be purely contractual or result from negligence. The liability in either
case is restricted to the duties as defined in the contract between or among the parties to the
contract. This is primary liability. Contracts may be oral or written. The rules of evidence
relating to contractual liability are strict.
The general rule is that written contracts cannot be varied by oral or other external evidence.
This is usually referred to as the four corners rule, or the entire contract doctrine, or an
integrated contract. This means that discussions, negotiations, and understandings accomplished prior to the execution of the contract are not admissible to vary the terms of the
written document.
There are circumstances in which the court may admit evidence to show that an ambiguity
exists or that other terms are incorporated by reference to other documents or discussions.
With this in mind, the designers should incorporate all of their contract terms in writing,
attaching an entire agreement or integration agreement clause. By doing so, they will ensure
that no duties other than those agreed between the designer and the client are imposed. This is
what the court will look to confirm the intention of the parties at the time of contracting.
However, the designer should keep in mind that contracts are very often premised on implied
terms. These implied terms are known as warranties. A warranty will not be found to exist in
all cases. Courts do not necessarily acknowledge an implied warranty that the design would
be suitable for the intended purpose when appropriate assurances are missing. In such a case,
the claimant has to show that the designer has been aware of the circumstances and still gave
an assurance or undertaking in the specific terms of the lawsuit.
NOTE:
This kind of contractual liability exposes the design professional to third-party
liability, because warranty liability is not limited to negligent performance.
This is an area in which the doctrine of privity of contract has been eroded. The result is an
increased exposure of the design professional to third-party claims.
Warranty liability is premised on representations that the work would be done in a professional
manner—that it would not be defective and it would conform to the contract documents. The
warranty theory establishes a standard of performance rather than a standard of care
exercised by the designer and installer as the basis for liability. This liability is best understood
by recognizing the changing role of the designer and is more applicable where the designer is
a hybrid of consultant/installer, designer/installer, or an installer.
OSP Design Reference Manual, 4th edition
2-4
© 2007 BICSI®
Chapter 2: Legal Considerations for the OSP Designer
Legal Issues, continued
The distinction between the expectations of the traditional designer in the context of the
separation of the five roles and the hybrid designer is that the traditional designer’s work does
not express or imply a warranty. Unless engaged as part of a design/build project, or when
employed as a project manager, the designer does not warrant that the work would be carried
out in a professional manner or in accordance with the specifications. Both the design/build
method of construction and the role of project manager create an obligation that the finished
project comply with the owner’s expectations. Therefore, the risk of the unknown contractually shifts from the owner to the design/build firm. Consequently, in this role, the designer is
required to perform exactly in accordance with the contractual specifications.
The loss of protection from liability to third parties by the erosion of the “economic loss
doctrine” is closely linked to the issues arising from the warranty liability. According to the
economic loss doctrine, the design professional has no liability to the entities to which the
design professional does not guarantee contractual privity for purely economic losses or
damages.
The economic loss doctrine does not apply in all of the United States. Therefore, design
professionals need to seek appropriate legal advice to determine whether or not the doctrine is
applicable in their area. The Florida Supreme Court ruled that the economic loss doctrine
originated in the context of product liability cases and as such “should not be invoked to bar
well-established causes of action in tort, such as professional malpractice.” The court thus
decided that action can be brought against a professional for negligence even for purely
economic damages.
In summary, the argument that there is no contractual relationship between the claimant and
the design professional may not succeed in some courts. Design professionals may, therefore,
find that they cannot hide behind contractual terms to escape liability. It may be tempting to
question the purpose of contracts. However, the importance of very clear contractual terms
for work and respective risks cannot be overstated. As little as possible should be left to
implication or imagination. Furthermore, OSP designers should only accept the work for which
they believe they are qualified.
Liability in Tort—Secondary Liability
Although liability for negligence can arise in a contract, it is a separate and distinct head of
liability. The distinction between contractual negligence and tortious negligence is that where
negligence is claimed under the contract, it will be restricted to, and hence determined in
accordance with, the terms of the contract.
Liability in tort is usually wider than the liability arising under a contract because it is premised
on a general duty to exercise due care and skill. Notwithstanding the contract terms, the
designer may become liable to third parties for negligence. This is what is commonly referred
to as secondary liability. It is based largely on expectation.
© 2007 BICSI®
2-5
OSP Design Reference Manual, 4th edition
Chapter 2: Legal Considerations for the OSP Designer
Legal Issues, continued
The expectation from design professionals varies based on whether at the material time they
are consulting, designing, or installing; in fact they may be performing all of the three tasks.
The consultant is in the business of giving professional advice, the designer creates a plan and
specification, and the installer implements the system according to the specifications and the
plan prepared by the designer. The separation of the various areas of the design professional’s
practice is for ease of analysis (bearing in mind that one person may perform all three
functions).
When acting as consultants, OSP designers may be liable for negligent misstatements because
they are primarily in the business of giving advice. This liability may be in contract or in tort.
Designers and installers may be liable for faulty designs or installations but generally not for
negligent misstatements, since they would be installing according to another designer’s
specifications. Liability may be found in a situation where the designer acting as a designer or
installer fails to design or install according to the owner’s specifications or fails to exercise
their professional judgment to ensure that the design is suitable for the particular environment.
Negligence has five elements:
•
Duty
•
Foreseeability
•
Breach of duty
•
Causation
•
Damage
The analysis usually begins by finding out who the neighbor is. This does not have a literal
meaning and therefore does not have to be the person next door. This inquiry sets the
framework for dealing with the first element of negligence—duty. The neighbors are the
category of persons who are entitled to circumvent the contract and sue design professionals
for damages. Therefore, the design professional owes a duty of care to this category of
persons.
In several U.S. jurisdictions, it is common for third parties to sue professionals with whom
they have no contractual relationship. It is the category of persons whom the design
professional should consider subject to injury if the job is not performed properly.
The persons likely to be affected by the location and placement of aerial pathway chosen by
the OSP designer would include persons who may suffer injury because the placement of
aerial cables has put them in contact with cables or their support due to incorrect height
allowances for the passage of heavy duty vehicles along a highway. The designer would be
subject to liability for persons who suffered injury in such circumstances, even though the
designer had no contractual relationship with them.
Duty imposes a standard of care and skill on the design professional. This is measured against
what is required in the profession by referring to the standards, codes, and norms that govern
that profession in the public interest. This duty varies according to the context in which the
OSP designer is working.
OSP Design Reference Manual, 4th edition
2-6
© 2007 BICSI®
Chapter 2: Legal Considerations for the OSP Designer
Legal Issues, continued
The term context refers to the place, time, or particular circumstances of the task that the
design professional is required to perform. It varies based on whether they are consulting,
designing, installing, or are engaged in a task for which they have no particular expertise. This
explains why judges decide each case according to its particular facts, though each case is
considered according to the principles of the law that governs the area of liability.
Design professionals must ensure to perform only within their areas of competence as the risk
of liability for negligence increases with each deviation from their particular expertise and
knowledge.
The scope of duty is limited or restricted by the concept of foreseeability. In general, a third
party’s opportunity to sue is restricted to whether the injury is of the kind that can reasonably
and objectively be predicted to result from the design professional’s act or omission.
In concrete terms, the designer’s liability is determined based on whether they knew or should
have known the risk associated with choosing, for example, one OSP-specific design metric
over another. The design professional is expected to investigate and learn if a certain type of
product, system or application is inadequate for the types of risks associated with the project
environment.
Only when the injury was reasonably foreseeable is the design professional found liable for
breach of the duty of care to a third party. The standard of reasonable conduct for the design
professional is determined on a case-by-case basis by juries.
The assessment of whether the duty has been breached or not includes, but is not limited to,
the following factors:
•
Reasonable efforts to ascertain the physical and operational environment of the OSP
design so that it can be determined whether the design would be appropriate
•
Contact with architects, engineers, general contractors, other trades, information
technology department, facilities department, or other entities relating to a particular
location or design
•
Internal procedures for determining OSP design
•
Response to negative information regarding the feasibility of the design
With appropriate risk management techniques, a design professional may successfully avoid
liability to third parties by minimizing the foreseeable risks and the class of persons to whom
the duty is owed.
Assuming that a likelihood or possibility of breach exists, the injury suffered by the third party
must have been caused or most likely have been caused by the design professional’s breach.
Therefore, the injured third party is required to show that it is more probable than not that the
design professional’s act or omission caused the claimed injury.
© 2007 BICSI®
2-7
OSP Design Reference Manual, 4th edition
Chapter 2: Legal Considerations for the OSP Designer
Legal Issues, continued
Having established liability, the third party must go further to demonstrate damage. The third
party must also show that loss was suffered as a result of the breach. The recoverable
damages can range from loss of earnings and loss of future earning capacity; past medical
expenses; future medical expenses; pain and suffering; disfigurement; and permanent or
temporary physical impairment. These are classic damages in tort theory. In the context of
OSP design, it appears that the courts would be challenged by quantifying the damages
resulting from the loss of information.
Limiting Legal Costs
Alternative Dispute Resolution
Litigation is very expensive both in terms of legal costs and the time spent away from business
to attend court, meet with the lawyers, or collate evidence. Therefore, it is often beneficial to
include alternative and less expensive methods of dealing with disputes when drafting
contracts.
These alternative methods are referred to under the general heading of alternative dispute
resolution (ADR). The two most common forms of ADR are:
•
Mediation.
•
Arbitration.
The effectiveness and benefits of these processes have been the subject of reviews
sponsored by the American Arbitration Association (AAA).
The global cost of civil litigation is soaring and businesses of all sizes are opting for a wider
palette of strategic dispute resolution strategies, according to a new study sponsored by the
AAA. This empirical study on ADR, entitled “Dispute-WiseSM Business Management:
Improving Economic and Non-Economic Outcomes in Managing Business Conflicts,”
investigates the practices, attitudes, and experiences of a broad sampling of corporate legal
departments from Fortune 1000 companies, midsize public companies, and privately held
businesses in their use of nonjudicial dispute resolution.
This pioneering study on the relationship between ADR and positive corporate outcomes
shows that a company may enjoy greater benefits by taking a strategic, multifaceted,
approach to managing the body of existing and future disputes rather than by aggressively
litigating each case. It also demonstrates that companies that take this approach can
effectively maximize the output of their legal staff while minimizing their legal department
costs.
OSP Design Reference Manual, 4th edition
2-8
© 2007 BICSI®
Chapter 2: Legal Considerations for the OSP Designer
Limiting Legal Costs, continued
The following are some of the study findings:
•
The study identified an index of eight particular traits that characterized the legal
departments of dispute-savvy companies. The survey also found that a number of specific
operational benefits are associated with dispute-wise business management practices for
these companies. It appears a company may glean benefits (e.g., better customer and
business partner relationships, lower costs, and more positive employee relations) by
managing effectively over time the total economic and noneconomic impact of their entire
range or portfolio of issues and disputes. In addition, the survey noted interesting
correlations between dispute-wise business management practices and positive economic
advantages.
•
“Legal departments that take a portfolio approach to resolving disputes (e.g., measuring
them against each other with the goal of minimizing overall risk, cost, time spent, and
resources expended) appear to garner several distinct benefits,” said Richard Naimark,
Senior Vice President of the AAA. “Moreover, it is clear that dispute-savvy companies
monitor their key business relationships and approach dispute resolution with that strategic
focus in mind” (Dispute-WiseSM).
Mediation
Mediation is a nonbinding, facilitated, negotiation process. Its aim is to produce voluntary and
acceptable settlement agreements between or among the parties that are involved in a dispute.
Although the process starts out as nonbinding, once an agreement is reached and duly signed
by the parties, it becomes binding.
A mediator is a person who is trained in dispute resolution, including negotiation techniques,
and is familiar with the art of making a deal. Mediators are neutral and do not offer legal
advice, although they are actively engaged in the discussion process, including narrowing
down the issues, offering alternatives, and directing the parties toward a settlement of the
dispute.
Mediation is less expensive in part because preparing for the mediation, including the
mediator’s fees, costs less than the regular court process (e.g., the filing of pleadings,
disclosure of documents, attendance for depositions). Mediation offers more flexibility insofar
as it is not restricted or bound by the rules of law or legal precedents. Making agreements is
thus broader and less laden by the rules.
Arbitration
Arbitration is more rule-laden than mediation. In arbitration, the arbitrator is required to apply
the law relating to the particular subject matter. Although having one arbitrator is not unusual,
it is more common to have a panel of three arbitrators. At least one arbitrator is a lawyer,
whereas the others may be drawn from among the persons familiar with the dispute’s subject
matter.
© 2007 BICSI®
2-9
OSP Design Reference Manual, 4th edition
Chapter 2: Legal Considerations for the OSP Designer
Limiting Legal Costs, continued
The arbitrators hear evidence in the same way as it is done in a court of law. However, the
rules of evidence are more relaxed. In addition, discovery is not as rigorous as pretrial
discovery and the more formal requirements of a trial (e.g., the preparation of briefs or closing
arguments) are not necessary.
To take the full advantage of ADR, it is recommended that it be included in the contract. In
some state jurisdictions, apart from court proceedings, mediation is by agreement and
arbitration is always by agreement.
The initial agreement makes arbitration mandatory between the parties. In the construction
industry, a standard AAA clause is used.
Generating standard form AAA clauses for use by OSP designers would be useful. Merely
stipulating arbitration without specific details is inadequate for giving a full effect to the
intentions. The intentions may be subject to differing rules of interpretation and the process,
therefore, must be specified. To name a few of the important details, the clauses must
stipulate the number of arbitrators, how they would be chosen, and whether the decision
would be unanimous or by majority.
Limiting the Design Professional’s Liability
OSP designers can benefit from some of the lessons already learned by the building
construction industry. Some of these liability avoidance techniques are summarized in this
section.
The erosion of the doctrine of privity suggests that design professionals have to be perceptive
about the contractual arrangements or their relationship with the owners and the contractors.
The construction industry has minimized this exposure by changing the manner of interaction
with the builders/owners. Such interaction was achieved by first changing the relationship
from a supervisory role to an inspection role. Second, the inspection role was reduced to the
role of observing the work for limited purposes of:
•
Ascertaining whether the work was professional.
•
Assessing whether the work generally conformed to the contract requirements.
•
Advising the owner whether to pay for the work.
The single most important precautionary measure is to avoid oral agreements. Given the
nature of the designer’s job, all contracts and amendments should be in writing.
In addition, risks can be more carefully allocated when they are fully recognized at the outset.
Independent legal advice is recommended to ensure that design professionals do not sign onesided contracts prepared by the contractors or the owners’ attorneys or contracts laden with
terms with very serious implications, particularly as related to risk allocation.
OSP Design Reference Manual, 4th edition
2-10
© 2007 BICSI®
Chapter 2: Legal Considerations for the OSP Designer
Limiting the Design Professional’s Liability, continued
Fairness is a requirement on both sides so that inasmuch as unfair contractual terms should
not be signed by one contract party, unfair contractual terms should not be imposed on the
other contract party. Courts look with disfavor on unfair contractual terms.
An unfair contract can be as bad as having no contract at all. It is also advisable to insert
provisions for early termination of the contract and for a reasonable limitation of damages
consequent on early termination.
The scope of the services to be provided should be clearly defined and closely regarded. Any
variation from the original terms must put in written form after a careful analysis of the risks
and costs involved or associated with the change. Warranties, indemnities and guarantees
should be avoided.
Limitations of liability are another method that can be used to allocate the risks associated
with a particular project. One of the most common expressions of limitation of liability clauses
is when the client and the designer agree to limit the design professional’s risk to the sum of
the professional fees.
With the evolution of high availability information technology (IT) sites like data centers, the
potential value of lost uptime due to consulting, design and/or installation of OSP facilities has
increased. If a critical error is traced back to the OSP designer, the amount of the claim can
be substantial. This is yet another reason to continue being educated on the legal issues arising
from ITS projects.
© 2007 BICSI®
2-11
OSP Design Reference Manual, 4th edition
Chapter 2: Legal Considerations for the OSP Designer
References
Agostini, John. “Legal Aspects of Risk Management of Design/Build Contracts.” Web article.
a/e ProNet, 1996. www.aepronet.org/pn/vol9-no1.html (accessed January 3, 2007).
American Arbitration Association. “Dispute-WiseSM Business Management: Is Your Company
Dispute-Savvy? Study Reveals Positive Outcomes of Effective Conflict Management. Web
article. American Arbitration Association, 2004. www.adr.org/dw (accessed January 3, 2007).
Dixon, Sheila (ed.). Lessons in Professional Liability, DPIC’s Loss Prevention Handbook
for Design Professionals. Monterey, CA: DPIC, 1996.
Gumbiner, Kenneth J. “Alternative Dispute Resolution: There is a Better Way.” Web article.
a/e ProNet, 1995. www.aepronet.org/pn/vol8-no1.html (accessed January 3, 2007).
OSP Design Reference Manual, 4th edition
2-12
© 2007 BICSI®
Chapter 3
Cable Types
Chapter 3 explains cabling purposes, cable types,
construction, physical specifications, design specifications,
and placement. Optical fiber, copper, coaxial, twinaxial,
and hybrid optical fiber coaxial cables and respective
subtypes are discussed in detail.
Chapter 3: Cable Types
Table of Contents
Cabling ............................................................................................... 3-1
Introduction ................................................................................................ 3-1
Recognized Cable ................................................................................ 3-3
Cable Types ................................................................................................ 3-3
Balanced Twisted-Pair Cable .......................................................................... 3-3
Optical Fiber Cable ....................................................................................... 3-4
75 Ohm Coaxial Cable ................................................................................... 3-4
Optical Fiber Cabling ........................................................................... 3-5
Introduction ................................................................................................ 3-5
Attenuation ................................................................................................ 3-8
Optical Fiber Attenuation Margin Calculations Worksheet ............................... 3-9
Calculating the Passive Cable System Attenuation ..................................... 3-11
Effects of Temperature on Optical Fiber Loss ............................................. 3-12
Splice Loss Values ................................................................................. 3-13
Verifying the Attenuation Margin ............................................................. 3-15
Checking Minimum System Loss ............................................................... 3-15
Final Analysis ....................................................................................... 3-16
Supportable Distance and Maximum Channel Attenuation ............................. 3-17
Optical Fiber Cable Types ............................................................................ 3-20
Loose Tube Cables ................................................................................ 3-20
Tight-Buffered Cables ............................................................................ 3-22
Central Tube Cable ................................................................................ 3-23
Ribbon Fiber ......................................................................................... 3-24
Blown Fiber .......................................................................................... 3-24
Hybrid Cables ....................................................................................... 3-28
Cable Specifications .............................................................................. 3-28
Color Coding ......................................................................................... 3-30
Balanced Twisted-Pair Copper Cabling .............................................. 3-31
Introduction .............................................................................................. 3-31
Selection Criteria ....................................................................................... 3-31
Resistance Design ................................................................................. 3-31
Copper Cable Transmission Characteristics ..................................................... 3-33
Cable Construction Types ............................................................................ 3-34
Insulation ............................................................................................ 3-35
© 2007 BICSI®
3-i
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Broadband Twisted-Pair Telecommunications Cable .......................................... 3-43
Plastic Insulated Conductor (PIC) Cable ......................................................... 3-44
Aerial Cable ............................................................................................... 3-45
Self-Supporting Cable ................................................................................. 3-47
Direct-Buried Cable .................................................................................... 3-52
Overview ............................................................................................. 3-52
Direct-Buried Outside Plant (OSP) Cable Designs ........................................ 3-52
Underground Cable ..................................................................................... 3-59
Overview ............................................................................................. 3-59
Underground Conduit Cable Designs ......................................................... 3-59
Outside Plant (OSP) Copper Designs, Internally Screened Cables .................. 3-64
Aerial Drop Wire ......................................................................................... 3-67
Direct-Buried Service Wire ........................................................................... 3-67
Coaxial Cabling ................................................................................. 3-68
Cable Selection ......................................................................................... 3-68
Mechanical Factors .................................................................................... 3-69
Center Conductor ................................................................................. 3-69
Dielectric ............................................................................................. 3-69
Outer Conductor ................................................................................... 3-69
Jackets ............................................................................................... 3-69
Electrical Factors ....................................................................................... 3-70
Aerial Applications ...................................................................................... 3-72
Direct-Buried Applications ........................................................................... 3-73
Design Criteria ........................................................................................... 3-74
Subscriber Service Drops ............................................................................ 3-75
Determining Bandwidth Requirements ............................................................ 3-79
Obtaining Loss Budgets for Electronics from the Customer ................................ 3-79
Twinaxial Cabling .............................................................................. 3-80
Introduction .............................................................................................. 3-80
Hybrid Fiber Coaxial Cabling .............................................................. 3-81
System Requirements ................................................................................. 3-82
Space Allocation ................................................................................... 3-82
Power ................................................................................................. 3-82
Applications .............................................................................................. 3-82
Appendix: Rural Utilities Service (RUS) Type Cable .......................... 3-84
Rural Utilities Service (RUS) Type Cable ......................................................... 3-84
References ....................................................................................... 3-85
Footnotes ................................................................................................. 3-88
OSP Design Reference Manual, 4th edition
3-ii
© 2007 BICSI®
Chapter 3: Cable Types
Figures
Figure 3.1
Cable sizing ............................................................................... 3-2
Figure 3.2
Duplex subscriber connector interface ............................................ 3-7
Figure 3.3
Loose tube cable cross section ................................................... 3-21
Figure 3.4
Tight-buffered cables ................................................................ 3-23
Figure 3.5
Tube cable .............................................................................. 3-25
Figure 3.6
ALPETH cable ........................................................................... 3-45
Figure 3.7
Self-supporting cable ................................................................ 3-47
Figure 3.8
Reinforced self-supporting cable ................................................. 3-50
Figure 3.9
PASP type design ..................................................................... 3-53
Figure 3.10
Filled ASP type cable ................................................................. 3-56
Figure 3.11
Filled ALPETH type cable ............................................................ 3-60
Figure 3.12
Underground (ductpic) cable ...................................................... 3-62
Figure 3.13
Air core screened cable ............................................................. 3-65
Figure 3.14
Filled screened cable ................................................................. 3-66
Figure 3.15
Coaxial cable ........................................................................... 3-68
Figure 3.16
Aerial coaxial cables .................................................................. 3-72
Figure 3.17
Armored cable .......................................................................... 3-73
Figure 3.18
Trunk and feeder system ........................................................... 3-75
Figure 3.19
Standard shield and quad shield construction (drop cable) .............. 3-76
Figure 3.20
Video link loss .......................................................................... 3-79
Figure 3.21
Twinaxial cable ......................................................................... 3-80
Figure 3.22
Optical fiber coaxial system ....................................................... .3-81
Tables
Table 3.1
Optical fiber cable performance by type ......................................... 3-6
Table 3.2
Calculating the optical fiber attenuation margin ............................... 3-8
Table 3.3
Calculating losses ..................................................................... 3-12
Table 3.4
Splice loss values in decibels ...................................................... 3-13
Table 3.5
System gain, power penalties, and the link loss
budget calculations ................................................................... 3-14
Table 3.6
Minimum system loss ................................................................. 3-16
Table 3.7
Supportable distances and channel insertion loss for
optical fiber applications by optical fiber type ............................... 3-17
Table 3.8
Supportable distances and channel insertion loss for
optical fiber applications by fiber type .......................................... 3-19
© 2007 BICSI®
3-iii
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Table 3.9
Example of color coding—individual optical fibers ............................ 3-30
Table 3.10
Loop gauging table ................................................................... 3-32
Table 3.11
Cable transmission characteristics ............................................... 3-33
Table 3.12
Insulation types ....................................................................... 3-35
Table 3.13
Cable composition types ............................................................ 3-36
Table 3.14
Cable sheath compositions ......................................................... 3-40
Table 3.15
Cable usage guide .................................................................... 3-42
Table 3.16
Common color code ................................................................... 3-44
Table 3.17
ALPETH cable ........................................................................... 3-46
Table 3.18
Self-supporting cable ................................................................ 3-48
Table 3.19
Reinforced self-supporting cable ................................................. 3-51
Table 3.20
PASP cables ............................................................................ 3-54
Table 3.21
Filled ASP type cable ................................................................. 3-57
Table 3.22
PE 39—Filled solid ALPETH cable .................................................. 3-58
Table 3.23
Filled ALPETH type cable ............................................................ 3-61
Table 3.24
Bonded STALPETH/ductpic cable ................................................. 3-63
Table 3.25
Cable attenuation at VSWR = 1.0, 50 ohm foam dielectric
and ambient 20 °C (68 °F) ......................................................... 3-74
Table 3.26
Coaxial attenuation at 20 °C (68 °F) over long distances ................ 3-74
Table 3.27
Drop cable and attenuation ........................................................ 3-76
Table 3.28
Drop cable and attenuation at maximum drop length ...................... 3-77
Table 3.29
Generic impedance for video infrastructure components .................. 3-78
Table 3.30
RUS acceptance cable-coding plan .............................................. 3-84
Table 3.31
Description of codes ................................................................. 3-84
Example
Example 3.1
Optical fiber attenuation margin calculations worksheet .................... 3-9
OSP Design Reference Manual, 4th edition
3-iv
© 2007 BICSI®
Chapter 3: Cable Types
Cabling
Introduction
The information transport systems (ITS) outside plant (OSP) designer must assess customer
requirements before selecting the type and size of cabling for a proposed OSP project. These
requirements include the:
•
Number of work areas and users.
•
Types of equipment.
•
Information to be transmitted by:
–
Voice.
–
Video.
–
Data.
•
Other low-voltage systems.
•
Distance involved.
•
Future growth.
•
Environmental conditions.
Selecting the appropriate type and size of cable is critical to the success of an OSP design.
To determine the requirements for a job, the designer must:
© 2007 BICSI®
•
Talk with the customer. The customer should know how many users or work areas will
be served by the OSP facilities. If not, the customer or consultant must initiate a survey.
•
Calculate the pair/strand requirements. Once the information is tabulated, all of the
requirements should be added back to the beginning of the route (see Figure 3.1). The
designer should begin with the building or work area point farthest from the main crossconnection. The cable should be sized to include a growth factor of 15 to 20 percent.
3-1
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Introduction, continued
Figure 3.1
Cable sizing
110
152
72
101
Bldg D
200-pair
cable
65
51
300-pair cable
Bldg E
200-pair
cable
262 155
173
85
Bldg B
100-pair
cable
Fill box legend
Planned future pair requirement
600-pair cable
Bldg G
200-pair
cable
482
309
Existing pair requirement
Bldg A
Once the requirements have been tabulated, the designer can then determine:
•
If optical fiber cable, balanced twisted-pair cable, or both are appropriate.
•
How many pairs of balanced twisted-pair or strands of optical fiber are required.
•
If there is a need for coaxial cable.
This chapter discusses the types of cable available along with their transmission
characteristics, construction specifications, cable coding descriptions, and advantages and
disadvantages. Methods for selecting the suitable optical fiber, balanced twisted-pair, or
coaxial cable also are addressed.
OSP Design Reference Manual, 4th edition
3-2
© 2007 BICSI®
Chapter 3: Cable Types
Recognized Cable
Cable Types
With the myriad of telecommunications services available, one particular cabling plan may not
be suitable to serve all of the resulting needs. Time, money, performance, and equipment
specifications become the determining factors in the selection process.
Currently, recognized cable includes:
•
Singlemode optical fiber (OS1).
•
50/125 μm multimode optical fiber (OM2 and OM3).
•
62.5/125 μm multimode optical fiber (OM1).
•
100 ohm balanced twisted-pair.
•
75 ohm coaxial.
Balanced Twisted-Pair Cable
Balanced twisted-pair cable transports information as electrical signals. Twisted-pair generally
is referred to as a balanced transmission medium because the signals on each of the
conductors of a pair are of equal value but have opposite phase or polarity.
The advantage of balanced twisted-pair is that it has a large installed base and is a familiar
technology. However, as the use of optical fiber cabling increases, these advantages dissipate.
The volume of copper plant still in place and capable of performing satisfactorily, as well as
the high cost of replacement, makes optical fiber an important media.
The disadvantages of balanced twisted-pair cable include:
© 2007 BICSI®
•
Higher sensitivity to external electromagnetic interference (EMI).
•
High bandwidth applications have distance limitations.
3-3
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Optical Fiber Cable
Optical fiber cable transports information as coded light pulses. Some advantages of optical
fiber cable are:
•
Extended distances.
•
Expanded bandwidth.
•
Immunity to EMI.
•
Low transmission loss.
•
Compact and lightweight materials.
•
Security.
Some disadvantages are that:
•
Optical fiber field connectorization may require different termination kits for each type of
connector and different installation procedures.
•
An optical fiber termination kit for a connector from one manufacturer may not be
capable of terminating another manufacturer’s connector, even though they are the same
style of connector.
•
Fan-out kits typically are required for field connectorization, specifically on OSP cables.
•
Field connectorization errors can result in spare part requirements and rework costs.
75 Ohm Coaxial Cable
Coaxial cable transports information as electrical signals. Community antenna television
(CATV) providers traditionally installed coaxial cable from their headend source point to the
subscribers. Coaxial cable is referred to as an unbalanced transmission medium because one
conductor is at ground value or zero volt potential and the other conductor is at a value offground. Coaxial cable also is used in OSP distribution for private networks, primarily for
broadband video services.
The advantages of 75 ohm coaxial cable are that it:
•
Is less susceptible to interference and radiation than balanced twisted-pair.
•
Has high bandwidth relative to balanced twisted-pair.
The disadvantages are that:
•
It is more expensive than other cable types.
•
Shield connections pose an increased risk of ground loops.
•
High bandwidth applications have distance limitations when compared with other media.
OSP Design Reference Manual, 4th edition
3-4
© 2007 BICSI®
Chapter 3: Cable Types
Optical Fiber Cabling
Introduction
Optical fiber technology is economically feasible and beneficial for use in most telecommunications systems, especially when cabling extends between buildings on a campus. While
balanced twisted-pair cabling often is placed between buildings to support and provide
telephony (voice) applications services, optical fiber cabling often is used to supplement the
balanced twisted-pair cabling to support other high-bandwidth applications.
In campus backbone environments, optical fiber is used between buildings for:
•
Voice.
•
Video.
•
Data.
•
Audio.
•
CATV.
•
Security and fire alarms.
In campus applications, it is an advantage to use optical fiber in backbones because of its
ability to serve several different transmission protocols and topologies by offering:
•
Increased distance.
•
Higher bandwidth applications.
•
All-dielectric cable.
•
Less susceptibility to EMI and lightning.
•
No crosstalk.
•
No grounding (earthing) requirement for all-dielectric cable.
A properly planned system can anticipate growth and provide network flexibility and longevity
for:
•
Voice.
•
Data.
•
Video.
•
Audio.
•
CATV.
•
Multimedia.
Often, a backbone comprising both multimode and singlemode optical fiber is recommended
to satisfy present and future needs in the backbone.
© 2007 BICSI®
3-5
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Introduction, continued
For backbone applications, the components in Table 3.1 are recognized.
Table 3.1
Optical fiber cable performance by type
Classification
Optical Fiber Type
Performance
OM1
62.5/125 μm Multimode
Minimum bandwidth of 200
and 500 MHz•km at 850 and
1300 nm, respectively.
OM2
50/125 μm Multimode
Minimum bandwidth of 500
and 500 MHz•km at 850 and
1300 nm, respectively.
OM3
50/125 μm 850 nm Laser
Minimum bandwidth of 2000
and 500 MHz•km at 850 and
1300 nm, optimized multimode
respectively.
OS1
Singlemode
Minimum bandwidth of
singlemode optical fiber
cable is not characterized in
the same manner as multimode.
The bandwidth of OS optical
fiber cable is considered to be
virtually unlimited.
km
MHz
nm
OM1
OM2
OM3
OS1
=
=
=
=
=
=
=
Kilometer
Megahertz
Nanometer
Optical multimode
Optical multimode 2
Optical multimode 3
Optical singlemode
OSP Design Reference Manual, 4th edition
3-6
© 2007 BICSI®
Chapter 3: Cable Types
Introduction, continued
Connectors must meet applicable requirements and environmental conditions for areas where
they are installed (e.g., Fiber Optic Connector Intermateability Standard [FOCIS]). The
subscriber connector (SC) interface, both duplex (568SC) and simplex (SC), is recognized
by many cabling standards for use as backbone and horizontal connectivity (see Figure 3.2).
Alternate connector designs such as small form factor (SFF) connectors and adapters that
meet applicable cabling standards requirements also may be used.
Figure 3.2
Duplex subscriber connector interface
Simplex connectors
B
A
A B
A
Horizontally mounted
B
A
A
B
B
B
OR
Vertically mounted
A
Pa
pa tch
ne
l
Duplex connector
B
A
User side
A
B
Cabling side
= Position A
= Position B
Multimode fibers frequently are referred to by the core and cladding diameter in micrometers
(μm). For example, a multimode optical fiber with a core diameter of 62.5 μm and a cladding
diameter of 125 μm typically is designated as 62.5/125 μm optical fiber.
© 2007 BICSI®
3-7
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Attenuation
The maximum permissible end-to-end system attenuation in a given link is determined by the
average transmitter power and receiver sensitivity. To analyze a system’s attenuation and
determine if the proposed electronics will operate over the cable plant, the steps illustrated in
Table 3.2 and Example 3.1 should be used and then the minimum system loss should be
checked.
NOTE:
Ensure the test setup simulates the actual system. (Use the jumpers or at least
include their losses in final calculations.)
Table 3.2
Calculating the optical fiber attenuation margin
Objective
Step
Calculation
Calculate the
passive cable
system attenuation.
1.
2.
3.
4.
Calculate the optical fiber loss.
Calculate the connector loss.
Calculate the splice loss.
Calculate other component losses.
OSP Design Reference Manual, 4th edition
3-8
© 2007 BICSI®
Chapter 3: Cable Types
Attenuation, continued
Optical Fiber Attenuation Margin Calculations Worksheet
Example 3.1 illustrates how to calculate the system attenuation margin to verify adequate
power. Detailed information for each alphabetical listing (e.g., parts A, B, C) is further
provided in the sections following Example 3.1.
Example 3.1
Optical fiber attenuation margin calculations worksheet
Part A. Calculating the Passive Cable System Attenuation
Step
1
2
3
4
5
© 2007 BICSI®
Calculate optical fiber loss
at operating wavelength
Calculate connector loss
(exclude transmit and
receive connectors)
Calculate splice loss
Calculate other components
loss
Calculate total passive
cable system attenuation
Cable distance
Individual optical fiber loss
Total fiber loss
Connector pair loss
Number of connector pairs
Total connector loss
Individual splice loss
Number of splices
Total splice loss
Total components (none)
Total fiber loss
Total connector loss
Total splice loss
Total components
Total system attenuation
3-9
×
×
×
+
+
+
1.5 km
1.5 dB/km
2.25 dB
0.75 dB
4
3.0 dB
0.3 dB
3
0.9 dB
0.0 dB
2.3 dB
3.0 dB
0.9 dB
0.0 dB
6.2 dB
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Attenuation, continued
Example 3.1
Optical fiber attenuation margin calculations worksheet, continued
Part B. Calculating the Link Loss Budget
Step
5
6
7
8
Example manufacturer’s
electronic specifications
Calculate system gain
Determine power penalties
Calculate link loss budget
System wavelength
Fiber type
Average transmitter output
Receiver sensitivity (109 BER)
Receiver dynamic range
Average transmitter power
Receiver sensitivity
System gain
Operating margin (none stated)
Receiver power penalties
(none stated)
Repair margin (2 fusion
splices at 0.3 dB each)
Total power penalties
System gain
Power penalties
Total link loss budget
1300 nm
62.5/125 μm
multimode
18.0 dBm
31.0 dBm
11.0 dB
18.0 dBm
31.0 dBm
13.0 dB
2.0 dB
0.0 dB
–
–
–
+
+
0.6 dB
2.6 dB
13.0 dB
2.6 dB
10.4 dB
–
Part C. Verifying Performance
9
Calculate system performance
margin to verify adequate
power
BER
dB
dBm
km
nm
=
=
=
=
=
NOTE:
Link loss budget
Passive cable system attenuation
System performance margin
10.4 dB
6.2 dB
4 .2 dB
–
Bit error rate
Decibel
Decibel milliwatt
Kilometer
Nanometer
4.2 is greater than 0. Therefore, the system will operate as installed.
OSP Design Reference Manual, 4th edition
3-10
© 2007 BICSI®
Chapter 3: Cable Types
Attenuation, continued
Calculating the Passive Cable System Attenuation
To calculate the passive cable system attenuation, total the values for the:
•
Optical fiber cable loss.
•
Connector loss.
•
Splice loss.
•
Other component losses.
NOTE:
© 2007 BICSI®
When working with existing cable plant, passive cabling system attenuation can be
measured directly. Table 3.3 explains how to calculate each of these losses.
3-11
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Attenuation, continued
Table 3.3
Calculating losses
To Calculate the . . .
You Must . . .
Optical fiber cable loss
Multiply the length of the proposed link by the
normalized cable attenuation in dB/km for the optical
fiber at the operating system wavelength.
NOTE:
Connector loss
Temperature may affect the loss of the
optical fiber cable. See Effects of
Temperature on Optical Fiber Loss.
Add the individual attenuation values in dB for
every connector pair along the optical fiber route,
from transmitter to receiver, excluding the transmitter
and receiver connectors (see Connector Loss Values).
NOTE:
When choosing link lengths that require more
than two connectors, selecting the lowest
loss connector may be important in order to
stay within the loss budget.
Splice loss
Add the individual local attenuation values in dB
for every splice along the optical fiber route, from
transmitter to receiver (see Splice Loss Values).
Other component
Add the attenuation values of any other components
(e.g., passive stars) that contribute to losses in the
optical fiber route, from transmitter to receiver.
dB = Decibel
k m = Kilometer
Add the values for each of these losses to get the total passive cabling.
NOTE:
Example calculations for the passive cabling system attenuation and its four
components are shown in Example 3.1.
Effects of Temperature on Optical Fiber Loss
Temperature changes may affect the loss of optical fiber cable. Loss variations due to
temperature changes can be as high as 2 decibels per kilometer (dB/km). Some
manufacturer’s specifications indicate the cable’s loss only at room temperature rather than
throughout the operating temperature range. Add an additional margin in dB/km to the
normalized optical fiber attenuation value when calculating the optical fiber link loss (see
Example 3.1, Part A, Calculating the Passive Cable System Attenuation) if the cable’s
specifications are:
•
For room temperature only.
•
Based on an average of several fibers.
OSP Design Reference Manual, 4th edition
3-12
© 2007 BICSI®
Chapter 3: Cable Types
Attenuation, continued
Splice Loss Values
General splice loss values for system planning and link loss analysis are given in Table 3.4.
Specific suppliers or contractors may use other values.
Table 3.4
Splice loss values in decibels
Splice Type
© 2007 BICSI®
Average
Multimode
Maximum
Singlemode
Average
Maximum
Fusion
0.05
0.3
0.05
0.3
Mechanical
0.10
0.3
0.10
0.3
3-13
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Attenuation, continued
Table 3.5 explains how to calculate the system gain, power penalties, and link loss budget.
Table 3.5
System gain, power penalties, and the link loss budget calculations
To Calculate the…
You Must…
System gain
Subtract the receiver sensitivity in dBm from the transmitter
average power in dBm. This gives the maximum allowable loss in
dBm between the transmitter and receiver.
Power penalties
Add the loss values for the:
• Operating margin*—This loss accounts for:
– Variations in transmitter center wavelength.
– Changes in transmitter average power and
receiver sensitivity that result from age.
– Variations in component temperature within the
operating range of the system.
• If the system manufacturer does not specify the
operating margin, use values of:
– 2 dB for light-emitting diodes (LEDs).
– 3 dB for lasers.
• Receiver power penalty*—Some manufacturers may specify
other power penalties (dispersion, jitter, bandwidth, or clock
recovery) that must be subtracted from the system gain. If these
are provided, they must be subtracted from the available system
gain.
• Repair margin*—If the cable is located where it could be cut or
damaged by accident, allow sufficient loss margin in the design
to accommodate at least two repair splices. If the cable is in a
high-risk area or an area where rerouting is anticipated, the
designer may decide to allow for more than two splices.
Link loss budget*
Subtract the total value in dB for all of the power penalties from the
system gain. The result is the link loss budget.
dB = Decibel
dBm = Decibel milliwatt
*
In some cases, the electronics manufacturer already will have calculated the link loss
budget. In these instances, it is usually safe to assume the operating margin (i.e.,
transmitter aging) and receiver power penalties have been included in the manufacturer’s
calculations. However, the repair margin usually is not included in a manufacturer’s link loss
budget calculations, unless the product documentation specifically states a repair margin.
When the manufacturer does not state a repair margin, the system designer must subtract it
from the system gain to determine the link loss budget.
OSP Design Reference Manual, 4th edition
3-14
© 2007 BICSI®
Chapter 3: Cable Types
Attenuation, continued
Verifying the Attenuation Margin
To verify the attenuation margin, subtract the passive cabling system attenuation from the link
loss budget. If the result is:
•
Above zero (i.e., the passive cabling system attenuation is less than the link loss budget),
the system has enough power to operate over the passive portion of the link.
•
Below zero (i.e., the passive cable system attenuation is more than the link loss budget),
the system does not have enough power to operate.
If the result is below zero and the system has not been installed, make design changes
(e.g., use lower-loss connectors, splices, optical fiber, or reroute the design) to reduce passive
system losses. In rare cases, it may be necessary to add active components with greater
system gains.
When working with existing cabling, passive cabling system attenuation can be measured
directly. Again, the test setup should simulate the actual system (i.e., jumpers should be used
or at least their losses should be included in the final calculations). Link loss calculations are
shown in Example 3.1.
Checking Minimum System Loss
After verifying that the electronics have enough power to operate, one more attenuation
check of the system design remains—comparing the link attenuation with the receiver’s
dynamic range to ensure the loss in the link is not too small (see Table 3.6).
Insufficient minimum system loss (i.e., loss in the link too small) is sometimes a problem when
a laser source is used in premises environments (i.e., where lengths are short).
To calculate the minimum required system loss, subtract the receiver’s dynamic range from
the system gain (both in dB) using Example 3.1:
© 2007 BICSI®
System gain
13 dB
Receiver’s dynamic range
– 11 dB
Minimum required system loss
= 2 dB
3-15
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Attenuation, continued
Table 3.6
Minimum system loss
If the Result Is…
Then…
Less than zero
No further checking is necessary as it is impossible to overdrive that
transmitter/receiver combination.
Greater than zero
The resulting number represents the minimum loss that must be
introduced into the link between the transmitter and receiver to
maintain the specified BER. The total optical fiber, connector, and
splice loss must exceed this value. Using the example in the Optical
Fiber Attenuation Margin Calculations Worksheet:
• Optical fiber loss:
2.3 dB
• Connector loss:
3.0 dB
• Splice loss:
0.9 dB
• Total
6.2 dB
6.2 > 2; therefore, the system will operate as installed.
BER = Bit error rate
dB = Decibel
If additional loss is required in a given link, it is easy to add an appropriate link attenuator to
the system. Attenuators are devices that can be inserted into optical fiber transmission
systems, usually at a point where there is a connector, to introduce additional loss. The two
types of attenuators are:
•
Fixed attenuators, which can cause a specific level of additional loss.
•
Variable attenuators, which can be tuned to a given link.
Final Analysis
The designer can determine whether the minimum loss criteria are met by measuring the
attenuation of each link after it is installed.
OSP Design Reference Manual, 4th edition
3-16
© 2007 BICSI®
Chapter 3: Cable Types
Attenuation, continued
Supportable Distance and Maximum Channel Attenuation
Table 3.7 provides information to assist in the selection of optical fiber cable and lists
maximum supportable distances and maximum channel attenuation for optical applications by
optical fiber type. Applications are identified using both industry standard and common names.
The maximum supportable distances and maximum channel attenuation apply to specific
assumptions and constraints provided in the notes. Different assumptions or constraints may
change the maximum supportable distance and maximum channel attenuation.
Tables 3.7 and 3.8 provide a guide to the testing specifications for applications.
Table 3.7
Supportable distances and channel insertion loss for optical fiber applications by optical fiber type
Maximum Supportable
Maximum
Distance 2 (m)
Insertion Loss 2 (dB)
Wavelength
(nm)
62.5/125
μm
50/125
μm
Singlemode 6
62.5/125
μm
50/125
μm 1
Singlemode 6
10BASE-FL
(Ethernet)
850
2000
2000
NST
12.5
7.8
NST
Token Ring 4/16
850
2000
2000
NST
13.0
8.3
NST
100BASE-FX
(Fast Ethernet)
1300
2000
2000
NST
11.0
6.3
NST
FDDI (Low Cost)
1300
500
500
NST
7.0
2.3
NST
FDDI (Original)
1300
2000
2000
40 000
11.0
6.3
10.0 to 32.0
ATM
52
155
622
1300
1300
1300
3000
2000
500
3000
2000
500
15 000
15 000
15 000
10.0
10.0
6.0
5.3
5.3
1.3
7.0 to 12.0
7.0 to 12.0
7.0 to 12.0
266
266 7
1062 7
1062
1300
850
850
1300
1500
700
300 3
—
1500
2000
500
—
10 000
—
—
10 000
6.0
12.0
4.0
—
5.5
12.0
4.0
—
6.0 to 14.0
—
—
6.0 to 14.0
1000BASE-SX 7
(Gigabit Ethernet)
850
220 4
550 5
—
3.2 8
3.9 8
1000BASE-LX 7
(Gigabit Ethernet)
1300
550
550
5000
4.0 8
3.5 8
Channel
Application
Fibre
Channel
ATM
dB
FDDI
m
nm
NST
=
=
=
=
=
=
—
4.7 8
Asynchronous transfer mode
Decibel
Fiber distributed data interface
Meter
Nanometer
Nonstandard
© 2007 BICSI®
3-17
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Attenuation, continued
Table 3.7
Supportable distances and channel insertion loss for optical fiber applications by optical fiber type,
continued
1
2
3
4
5
6
7
8
A worst-case source coupling loss of 4.7 dB is used when coupling 50/125 μm optical fiber to an LED source
optimized for use with 62.5/125 μm optical fiber. This coupling loss is based on the theoretical maximum
coupling loss. 10BASE-FL specifies 5.7 dB maximum coupling loss into 50/125 μm optical fiber. Token ring,
FDDI (low cost), FDDI, and 100BASE-FX specify 5.0 dB maximum coupling loss into 50/125 μm optical fiber.
NST (nonstandard) entries indicate where this standard does not specify support for the media, but where
equipment is commonly available to convert the native application signals to a form compatible with the nonnative media.
300 m (984 ft) capability specified in Fibre Channel update, FC-PH-2.
For 62.5/125 μm optical fiber, IEEE specifies 220 m (721 ft) for 160/500 MHz•km modal bandwidth and
275 m (902 ft) for optical fiber with 200/500 MHz•km modal bandwidth.
For 50/125 μm optical fiber, IEEE specifies 500 m (1640 ft) for 400/400 MHz•km modal bandwidth and 550 m
(1804 ft) for 500/500 MHz•km modal bandwidth.
Power budget and distance capability depend on classification option of transmitter and receiver. Distance
specified is for the highest power budget option.
This is a laser-based application. When not so noted, multimode applications are LED-based.
Maximum channel insertion loss based on channel insertion loss plus unallocated margin from IEEE 802.3z.
NOTE:
Distances for specific implementations should be verified with application standards.
NOTE: Many manufacturers have propriety variation of the 1000BASE-X standard
allowing for longer transmission distances (5 km [3.1 mi] to 20+ km [+12.4 mi])
over singlemode fiber. These long-haul variations are accomplished by using
higher quality and/or more powerful laser chips.
OSP Design Reference Manual, 4th edition
3-18
© 2007 BICSI®
Chapter 3: Cable Types
Attenuation, continued
Table 3.8
Supportable distances and channel insertion loss for optical fiber applications by fiber type
Application
Wavelength
(nm)
Maximum Supportable
Distance 1 (m)
Multimode 2
62.5/125
μm
10/100BASE-SX
850
300
10GBASE-S
850
10GBASE-L
1310
NST
10GBASE-E
1550
NST
10GBASE-LX4
1300
300
10GBASE-LX4
1310
—
26 4
Maximum Channel
Insertion Loss 1 (dB)
Singlemode 9
850 nm
Laser-Opt.
50/125
50/125
μm
μm 3
300
Multimode 2
Singlemode
62.5/125
μm
50/125
μm
850 nm
Laser-Opt.
50/125
μm 3
300
NST
4.0
4.0
4.0
NST
300
NST
2.6 6,7
2.3 6,8
2.6
NST
NST
NST
10 000
NST
NST
40 000
300 11
300
—
—
—
10 000
82 5
9
NST
NST
NST
6.0
NST
NST
NST
11.0 10
2.5 6,12
2.0 6,12
2.0 6,12
—
—
—
—
6.6 6
dB = Decibel
m = Meter
nm = Nanometer
1
NST (nonstandard) entries indicate where this standard does not recognize use of the media, but
where equipment may be available to convert the native application signals to a form compatible with the
nonnative media.
2
Specifications shown in this table are for ANSI/TIA/EIA-568-B.1 recognized optical fiber types. Specifications
for other nonrecognized types of optical fibers are included in these footnotes where applicable.
3
850-nm laser-optimized 50/125 μm multimode optical fiber supports the same maximum channel distances
and insertion losses as 500/500 MHz•km 50/125 μm multimode optical fiber for applications specified within
ANSI/TIA/EIA-568-B.1.
4
For 62.5/125 μm optical fiber, IEEE specifies 26 m (85 ft) for optical fiber with 160/500 MHz•km modal
bandwidth and 33 m (108 ft) for optical fiber with 200/500 MHz•km modal bandwidth.
5
For 50/125 μm optical fiber, IEEE specifies 66 m (216 ft) for optical fiber with 400/400 MHz•km modal
bandwidth and 82 m (269 ft) for optical fiber with 500/500 MHz•km modal bandwidth.
6
Includes maximum channel insertion loss plus additional allowable insertion loss.
7
For 62.5/125 μm multimode optical fiber, IEEE specifies 2.6 dB for optical fiber with 160/500 MHz•km modal
bandwidth and 2.5 dB for optical fiber with 200/500 MHz•km modal bandwidth.
8
For 50/125 μm multimode optical fiber, IEEE specifies 2.2 dB for optical fiber with 400/400 MHz•km modal
bandwidth and 2.3 dB for optical fiber with 500/500 MHz•km modal bandwidth.
9
Channels are specified within ANSI/TIA/EIA-TIA-568-B.1 up to 3 km (9840 ft). Distances provided within this
table are the maximum distances specified within IEEE 802.3 and invoke cabling specifications that may
differ from 568B.3.
10 10GBASE-E channels are specified to have a minimum of 5 dB and maximum of 11 dB channel insertion
loss.
11 For 50/125 μm multimode optical fiber, IEEE specifies 240 m (787 ft) for optical fiber with 400/400 MHz•km
modal bandwidth and 300 m (984 ft) for optical fiber with 500/500 MHz•km modal bandwidth.
12 The maximum channel insertion loss is allowed to be up to 0.5 dB higher than the value shown when
including loss from mode conditioning patch cords.
© 2007 BICSI®
3-19
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Optical Fiber Cable Types
Optical fiber cables are classified by their:
•
Function.
•
Buffering mechanism.
Common functions in customer premises include:
•
Interbuilding backbone.
•
Intrabuilding backbone.
•
Horizontal distribution.
•
Patch cords and equipment cables.
The two types of buffering mechanisms for optical fiber cable are:
•
Loose tube—used in OSP aerial, underground, and direct-buried applications with limited
applications inside of buildings.
•
Tight-buffered—used in OSP aerial, underground, and direct-buried applications with
many additional applications inside of buildings.
NOTE:
Two types of tight-buffered cables are those suitable for installation inside of
buildings and those suitable for use in the OSP environments (e.g., aerial,
underground, direct-buried).
Loose Tube Cables
Loose tube cables are constructed so the optical fibers are decoupled from tensile forces that
the cable may experience during installation and operation (see Figure 3.3). Loose tube cables:
•
Are more robust than tight-buffered cables.
•
Are designed and proven for long outdoor runs.
•
Are less expensive than indoor cable per optical fiber meter, specifically at optical fiber
counts above 24.
•
Have better packing density.
OSP Design Reference Manual, 4th edition
3-20
© 2007 BICSI®
Chapter 3: Cable Types
Optical Fiber Cable Types, continued
Figure 3.3
Loose tube cable cross section
Central member
Loose buffer tube
Fiber bundle
Tensile strength
member
Inner sheath
Steel tape armor
(optional)
Outer sheath
(optional)
NOTE:
This illustration is not to scale.
Loose tube cables are available in:
© 2007 BICSI®
•
Armored constructions for use in direct-buried applications.
•
All dielectric constructions for use in aerial and underground applications.
•
Limited listings for use within buildings according to some national codes, standards, and
regulations as qualified by nationally recognized testing laboratory (NRTL) requirements.
3-21
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Optical Fiber Cable Types, continued
Tight-Buffered Cables
Tight-buffered fibers generally have a 900 μm coating applied directly to the optical fiber.
Some applications for tight-buffered cable are:
•
Intrabuilding backbone.
•
Horizontal distribution.
•
Patch cords and equipment cables.
•
Armored constructions for use in direct-buried applications.
•
All dielectric constructions for use in aerial and underground applications.
•
Limited listings for use within buildings according to some national codes, standards, and
regulations as qualified by NRTL requirements.
Tight-buffered cables are usually more sensitive to adverse temperatures and outside forces
than loose tube cables and are desirable because of their:
•
Increased physical flexibility.
•
Smaller bend radius for low optical fiber count cables.
•
Easier handling characteristics in low optical fiber counts.
•
Readiness for connectorization.
Two typical constructions of tight-buffered cables (see Figure 3.4) are:
•
Distribution design, which has a single jacket protecting all the tight-buffered optical
fibers.
•
Breakout design, which has an individual jacket for each tight-buffered optical fiber.
The distribution design cables are recommended for typical installations because of lower cost
and smaller diameter. Generally, large optical fiber count distribution cables are constructed in
a unitized design in which an inner jacket is placed around units of 6 or 12 fibers.
In outdoor environments, cables recommended by the manufacturer for outdoor use should be
used. Loose tube cables often are recommended because they:
•
Are rugged.
•
Are specified to operate over a wide temperature range.
•
Allow higher optical fiber densities per sheath size than tight-buffered designs. Where
duct space is limited, this becomes a significant factor.
OSP Design Reference Manual, 4th edition
3-22
© 2007 BICSI®
Chapter 3: Cable Types
Optical Fiber Cable Types, continued
Loose tube or tight-buffered cable, either alone or in combination, may be used in conduits
below the frost line. Tight-buffered cables are not recommended for use above the frost line
because they may be subject to damage from freezing water or moisture.
NOTE:
National codes, standards, or regulations (e.g., National Electrical Code® [NEC®])
may limit the use of exposed unlisted OSP cable to the first 15 m (49 ft) within the
building from the point of entrance. Local codes may be more restrictive.
Figure 3.4
Tight-buffered cables
Distribution design
Breakout design
Fiber
Fiber
Buffer
Buffer
Tensile strength
member
Tensile
strength
member
Subunit
jacket
Tensile strength
member
Central
member
Outer
jacket
Central
member
Outer
jacket
Central Tube Cable
Central tube cable, also known as single loose tube, core tube, or unitube cables, utilizes a
central tube that houses a specified number of fibers.
The fibers, and unit groupings when required, are color coded for identification. The central
tube may be water blocked by either gel or water-blocking tape or powder. The central tube is
reinforced by one of several methods, including fiberglass or aramid yarns, metallic armor rigid
fiber-reinforced polymer rods, or steel rods placed around or adjacent to the central tube. A
protective outer jacket is applied overall.
© 2007 BICSI®
3-23
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Optical Fiber Cable Types, continued
Armor and jacket options make the design suitable for use in indoor and outdoor, direct burial,
underground conduit, and aerial installations.
Some advantages of this design are that:
•
It has a high fiber density and compact size.
•
The design provides excellent mechanical protection to fibers.
•
It is a mature, proven design.
Some potential disadvantages of the design are that:
•
Armored designs may lack flexibility during installation.
•
Opening the central tube exposes all fibers in the cable.
•
Designs featuring rigid rods exhibit preferential bend behavior.
Ribbon Fiber
Ribbon fiber designs can be single tube or multitube, much like the designs for bundled fiber.
The only difference is that the fiber is bound in a flat array or ribbon.
This design incorporates several fibers, usually 12, into a ribbon. One or more of these ribbons
are enclosed inside a water-blocked central tube. Water blocking may be accomplished by gel
or water-blocking tapes or powders.
Water-blocking strength members surround the central tube to provide tensile strength.
Strength members may be dielectric or metallic. A protective outer jacket is applied overall.
Armor and jacket options make the design suitable for use in indoor and outdoor, direct burial,
underground conduit, and aerial installations.
Some advantages of this design are that:
•
It is suitable for mass fusion splicing.
•
The design has a high fiber density and compact size.
•
It provides excellent mechanical protection of fibers.
•
It is a mature, proven design.
A disadvantage of the design is a higher initial cost due to the added step of ribbonizing.
Blown Fiber
A blown fiber network utilizes a point-to-point infrastructure of microtubes used in lieu of
traditional innerduct and conduit systems to form the topology between buildings and within
buildings. The tubes (tube cables) are left empty in order to blow any type of fiber bundles
when and where they are needed via compressed air. Fiber bundles can be blown into any
route of connected tubes.
OSP Design Reference Manual, 4th edition
3-24
© 2007 BICSI®
Chapter 3: Cable Types
Optical Fiber Cable Types, continued
Although not new to other areas of the world, the benefits of blown fiber are rapidly
becoming more widely accepted in the United States. Consequently, a new international
standard for blown fiber has been written and is now nearing publication.
Blown fiber has numerous applications, including:
•
General campus.
•
Premises.
•
Local area network (LAN).
•
Residential fiber to the home (FTTH).
•
Metropolitan area network (MAN).
Blown fiber usually is deployed in organizations where current or future requirements exist,
future network expansion is expected or unknown, and future optical fiber strand density is
unknown. Many organizations find valuable the capability of blowing fiber several kilofoot
into tubes when and where required.
Nearly all blown fiber systems consist of five components:
•
Tube cable
•
Optical fiber bundles or fiber units
•
Tube connecting or coupler accessories
•
Premise connectivity enclosures
•
Blowing head and blowing equipment
Tube cables are central to the architecture of a blown fiber system and are available in the
United States in a wide variety of designs depending on the application (see Figure 3.5). The
installation environment typically determines tube cable type. Predominately, tube cables are
5 mm (0.2 in) outside diameter (OD) and 3.5 mm (0.138 in) inside diameter (ID) and are
available for OSP applications in all-dielectric, aluminum tape, and armored versions. Like
OSP cables, they can be directly buried, pulled through conduit, directly bored, or lashed
aerially. By design, tube cables enable simple transitions between tube cable types, be it OSP,
intrabuilding, or a combination of both.
Figure 3.5
Tube cable
Polyethylene outer
jacket
5 mm (0.2 in) OD
3.5 mm (0.14 in) ID
Co-extruded low
friction linear
OSP tube cable example
ID
in
mm
OD
OSP
© 2007 BICSI®
=
=
=
=
=
Inside diameter
Inch
Millimeter
Outside diameter
Outside plant
3-25
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Optical Fiber Cable Types, continued
Optical fiber bundles or fiber units typically are produced in two, four, eight, and twelve fiber
strands encased in coatings and an outer jacket. The OD of these fiber units is less than
1.5 mm (0.06 in) and depending on the fiber strand count typically will range from 1 mm
(0.039 in) to 1.5 mm (0.06 in). The coating and jacketing of the fiber unit is environmentally
independent and will default to the environmental rating of the tube cable once the fiber unit
is blown in.
Fiber units are available in all standard micron and core varieties such as singlemode fiber
(SMF) and multimode fiber (MMF). MMF is commonly available for premises-based lightemitting diode (LED) and laser-optimized applications. As in conventional optical cable, the
application will determine what fiber type is used.
The same optical glass that is used to manufacture conventional optical cable is used in blown
fiber. Therefore, once the blown fiber unit is “blown in,” conventional processes are employed
for terminating conventional connectors and testing fiber links. The physical construction of
the fiber unit differs from a conventional optical cable since there is no requirement for rugged
jacketing and strength members because the process of deployment is blowing versus pulling.
Connectors are used to connect (splice) individual sections of tubing and to route various
tubes to lateral runs such as building entrance conduits. Specialized connectors or couplers
are usually available per application requirements such as gas sealing connectors for special
applications.
Blown fiber technology employs similar enclosures, splice cases, and fiber distribution
hardware as conventional optical cable. Since blown fiber technology requires connecting
individual tubes versus splicing individual fiber strands, the protective enclosures where these
tubes are connected often are referred to as tube distribution units (TDUs) or tube distribution
enclosures (TDEs):
•
The ITS OSP designer and or installer shall choose a TDE size based on the number of
tubes to enter the enclosure.
•
Tube distribution hardware may be underground, aboveground, wall, floor, rack, or ceilingmounted to provide better protection and geometry for distribution.
•
Enclosures (e.g., National Electrical Manufacturers Association [NEMA] type 4 and 4X)
or properly rated splice cases shall be used in areas where hosing and splashing
environmental conditions exist.
•
Enclosures (e.g., NEMA 6 and 6P) or properly rated splice cases shall be used in areas
where temporary or long-term flooded environmental conditions exist.
•
Grips, bushings, grab rings, or similar devices should be used to secure tube cables to
outdoor enclosures.
OSP Design Reference Manual, 4th edition
3-26
© 2007 BICSI®
Chapter 3: Cable Types
Optical Fiber Cable Types, continued
The fifth and final component to a blown fiber system is the actual blowing equipment. A
blowing head and compressed air should be employed for each fiber unit blown. The blowing
head guides and controls the rate at which the fiber unit is installed into the tube. It also
prevents the fiber unit from damage and can be employed for recovery situations. Maximum
flow rate is 1032 kilopascals (kPa [150 pound-force per square inch (psi)]), and air
compressors should be set for automatic shutdown if this flow rate is exceeded.
NOTE:
BT Mark 2 standard tubes are 5 mm OD and 3.5 mm ID. The Mark 2 blown fiber
standard is an open technology that specifies the use of compressed air as the
source for blowing fiber units.
Most blown fiber systems publish maximum blowing distances of 1 km (3280 ft) without
employing advanced blowing techniques. Advanced blowing techniques, such as a midspan
blow, will enable a fiber unit to be blown much greater distances.
Step
Design Considerations
1.
Fiber bundle design—Being a nondark fiber system, the first question that needs
to be addressed is how many fibers will be lit day one. Designing the number of
fiber units to the lit fibers day one is crucial, for this system does not require an
overbuild of dark fibers.
2.
Tube cable design—Crucial to the system life cycle, first map the tube cable to
the installation environment; second, design dark tubes for the future and moves,
adds, or changes (MACs). Typically, a 3:1 ratio (i.e., three tubes to every fiber
unit) at a minimum will satisfy any charted or uncharted growth.
3.
Tube distribution hardware—TDEs or TDUs should be installed wherever two or
more tube cables meet, except at in-line or straight-through splices. The
enclosure must represent the installation and environmental requirements.
4.
Tube cable plant interconnection design—This ensures a successful end-to-end
cabling system design and route identification of dark tubes and lit blown fiber
tubes. The interconnection plan enables fewer MACs.
5.
Fiber distribution hardware—Fiber distribution hardware can be wall or rack
mounted units typically used in conventional optical cable. Action must be taken
to provide protection for the fiber units.
6.
Miscellaneous parts, tools, and equipment—Depending on the application,
installation environment, local or national codes, and other issues, this section
should list any miscellaneous concerns.
7.
Overall costs.
Since a blown fiber system is a long-term investment, providing increased system life cycle
versus conventional optical cable, it is the designer’s responsibility to be able to articulate the
total installed costs, including materials, installation, termination, maintenance, and MACs.
© 2007 BICSI®
3-27
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Optical Fiber Cable Types, continued
Hybrid Cables
Hybrid cables, often referred to as composite cables, can contain combinations of copper
pairs, optical fibers, coaxial cables, and other low-voltage conductors. Environments for hybrid
cables are:
•
Long haul.
•
Premises.
•
Campus.
OSP cables for long-haul applications are available with voice-grade balanced copper twistedpairs. These pairs may be used for convenience in long-haul situations with a remotely located
splice point or to power network equipment. As premises applications are relatively short,
these pairs usually are not required.
Cable Specifications
Manufacturer-specific specifications generally allow ordering of optical fiber cable with the
following characteristic options:
•
•
•
Optical fiber design:
–
Multimode
–
Singlemode
–
Singlemode, dispersion shifted
–
Singlemode, dispersion unshifted
–
Singlemode, low water peak
–
Singlemode, zero water peak (ZWP)
Cable core design:
–
Filled
–
Dry water block
–
Nonfilled
Sheath design:
–
Optical power ground wire (OPGW)
–
All-dielectric self-support (ADSS)
–
Dielectric
–
Self-supporting
–
Armored self-supporting
–
Metallic
OSP Design Reference Manual, 4th edition
3-28
© 2007 BICSI®
Chapter 3: Cable Types
Optical Fiber Cable Types, continued
•
–
Stainless steel
–
Coated steel
–
Nothing over sheath
–
Self-supporting
•
Number of optical fibers
•
Wavelength:
•
© 2007 BICSI®
Oversheath design:
–
Singlemode 1310/1550 nanometer (nm)
–
Singlemode, dispersion shifted 1550 nm
–
Multimode 850 nm, 1300 nm
Transmission parameters:
–
Attenuation (cable and link)
–
Return loss (link)
3-29
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Optical Fiber Cable Types, continued
Color Coding
Individual optical fibers are identifiable by established color codes. An example of a common
color-code scheme is shown in Table 3.9.
Table 3.9
Example of color coding—individual optical fibers
Fiber
Color
1
Blue
2
Orange
3
Green
4
Brown
5
Slate
6
White
7
Red
8
Black
9
Yellow
10
Violet
11
Rose
12
Aqua
In this example of loose tube optical fiber cables with more than 12 fibers, the fibers are
grouped within color-coded tubes. Each tube contains a specified number of fibers, typically
6, 8, 12, or 24. The tubes are color coded using the same color code for optical fiber (e.g., the
first tube is blue, the second is orange). The fibers within the tube would use the specified
color code. When a cable contains both singlemode and multimode optical fibers, singlemode
fibers typically are contained within the first group of tubes unless otherwise requested.
NOTE:
In cables with 24 optical fibers, some manufacturers use a white and a black or
gray tube. The first group of fibers, or the singlemode fibers, may be grouped within
the white tube.
For tight-buffered cables with more than 12 optical fibers, the fibers are grouped within
sequentially numbered tubes typically containing either 6 or 12 fibers. The fibers within the
tube use the color code shown in Table 3.9. Where the cable contains both singlemode and
multimode fibers, the singlemode fibers typically are grouped within sequentially numbered
yellow tubes, while the multimode fibers are grouped within sequentially numbered orange
tubes.
OSP Design Reference Manual, 4th edition
3-30
© 2007 BICSI®
Chapter 3: Cable Types
Balanced Twisted-Pair Copper Cabling
Introduction
Balanced twisted-pair copper cabling is feasible and applicable for a wide range of
telecommunications systems, including telephony, data, premises, and special applications.
In interbuilding backbone environments, balanced twisted-pair cabling is used between
buildings for:
•
Voice.
•
Data.
•
Security and fire alarms.
Selection Criteria
Resistance Design
Traditional balanced twisted-pair cable selection is based on resistance design of the cable.
Balanced twisted-pair cable exhibits a resistance to current flow, measured in ohms; they
typically are available in up to four sizes that may be defined in American wire gauge (AWG)
or metric equivalent sizes: 19 AWG [0.91 mm (0.036 in)], 22 AWG [0.64 mm (0.025 in)],
24 AWG [0.51 mm (0.020 in)], and 26 AWG [0.41 mm (0.016 in)]. The gauge of the wire is
proportionate to its resistance per unit length at a specified temperature.
The length of a cable loop from the switch to a customer depends on three factors:
•
Resistance of the cable in ohms
•
Signaling limits of the telephone and terminating device switch in ohms
•
Pair loading
Since every customer in a loop (see Table 3.10) potentially could require a different resistance
design, the telephone industry developed a transmission design standard known as gauge
coding area number (GACAN).
GACAN was developed to eliminate individual circuit design and to identify distances that a
specific gauge or combination of gauges could serve. The use of a resistance design
worksheet is typical for traditional copper loop design. GACAN limits usage to no more than
two cable gauges.
© 2007 BICSI®
3-31
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Selection Criteria, continued
Table 3.10
Loop gauging table
GACAN Less than 9.1 km (30.0 kft)
Subscriber Loop Design
Gauging
Code Area
1
2
3
4
5
26
26
24
24
24
1
Design
Range
(ohms)
1300
GACAN
kft
km
1
2.4 (7.8)
=
=
=
22
2
3
GACAN Area from
Central Office km (kft)
2
3
4
4.8 (15.6)
6.0 (19.8)
4
5
5
7.4 (24.4) 9.0 (29.6)
Gauge coding area number
Kilofoot
Kilometer
The second factor in loop design is the transmission signaling limits of the switch. These limits
are based on the switch’s ability to deliver signaling at various loop lengths. Earlier switch
platforms could service loops that exhibited resistance of up to 1300 . Depending on the cable
AWG makeup, the resistance of the loop length would vary. As switch technology evolved, the
resistance design limits increased to 1500, 1800, and 2100 , allowing greater loop lengths.
The third factor impacting loop design is pair loading. A load coil is a device designed to
counter the effect of capacitance buildup in loop lengths over 5.5 km (3.4 miles [mi]). The
capacitance buildup within a pair is the primary reason for the manufacturing of low
capacitance (cap) cable. The effect of pair loading has become a major reason for the
development of current serving area design parameters for local loops.
OSP Design Reference Manual, 4th edition
3-32
© 2007 BICSI®
Chapter 3: Cable Types
Copper Cable Transmission Characteristics
Table 3.11 is a representative table of OSP copper transmission characteristics. These values
may vary by manufacturer. Contact the manufacturer to obtain the specific values for the
design.
Table 3.11
Cable transmission characteristics
Exchange Cable Electrical Requirements
Solid Insulated
Foam-Skin Insulated
Aircore
19
Mutual Capacitance, Average
@ 73 ± 4 ºF, 1 kHz (nF/mile)
=12 pair
>12 pair
Mutual Capacitance, Maximum
@ 73 ± 4 ºF, 1 kHz (nF/mile)
= 12 pair
> 12 pair
Capacitance Difference, Maximum
@ 23 ± 2 ºC = 75 pair (%)
Capacitance Unbalance, Maximum
Pair-to-pair @ 73 ± 4 ºF (pF/kft)
Individual
rms (>12 pair only)
Capacitance Unbalance, Maximum
Pair-to-ground @ 73 ± 4 ºF (pF/kft)
Individual pair
Cable average (>12 pair only)
Lot average (>12 pair only)
dc Conductor Resistance, Maximum
@ 68 ºF (ohms/sheath-mile)
Individual conductor
Lot average
dc Resistance Unbalance, Maximum
Individual pair %
Cable average %
Lot average %
Dielectric Strength, Minimum (kV)
Conductor to conductor
Core to shield, single jacket
Core to shield, double jacket
Insulation Resistance, Minimum
(gigohm-mile)
Attenuation, Maximum Average
@ 68 ºF, .772 MHz (dB/kft)
>12 pair
=12 pair
ELFEXT, Minimum
@ 0.772 MHz (dB/kft)
Mean power sum
Worst pair power sum
NEXT, Minimum
@ 0.772 MHz (dB/kft)
Mean power sum
Worst pair power sum
db
dc
ELFEXT
kft
kHz
kV
=
=
=
=
=
=
24
26
19
22
Foam-Skin Insulated
Filled Core
24
26
19
22
24
Filled Core
26
19
22
24
83 ± 7
83 + 4/-5
83 ± 7
83 + 4/-5
83 ± 7
83 ± 4
83 ± 7
83 ± 4
94
92
94
92
94
92
94
92
26
No Requirement
80
25
80
25
80
25
80
25
800
175
105
800
175
105
800
175
120
800
175
120
45.0
91.0
144.0
232.0 45.0
91.0
144.0
232.0
45.0
91.0
144.0
232.0 45.0
91.0
144.0 232.0
44.0
88.5
140.0
225.0 44.0
88.5
140.0
225.0
44.0
88.5
140.0
225.0 44.0
88.5
140.0 225.0
5.0
10
20
5.0
5.0
5.0
5.0
1.5
1.5
1.5
1.5
1.1
1.1
1.1
1.1
4.0
10
20
3.0
10
20
2.4
10
20
-5
20
1.4
5
20
1.2
5
20
1.0
5
20
7.0
15
20
5.0
15
20
4.0
15
20
2.8
15
20
4.5
10
20
>1.0
>1.0
>1.0
3.6
10
20
3.0
10
20
2.4
10
20
>1.0
3.3
3.6
4.7
5.2
5.9
6.5
7.4
8.1
---
5.0
5.5
6.3
6.9
7.9
8.7
2.8
3.1
4.0
4.4
5.0
5.5
6.4
7.0
3.2
3.5
4.5
5.0
5.6
6.2
7.0
7.7
51
45
49
43
49
43
47
43
51
45
49
43
49
43
47
43
49
43
47
43
49
43
47
43
51
45
49
43
49
43
47
43
Decibel
Direct current
Equal level far-end crosstalk
Kilofoot
Kilohertz
Kilovolt
© 2007 BICSI®
22
Solid Insulated
Aircore
47
42
MHz
NEXT
nF
pF
rms
47
42
=
=
=
=
=
47
42
47
42
Megahertz
Near-end crosstalk
Nanofarad
Picofarad
Root-mean-square
3-33
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Cable Construction Types
The Insulated Cable Engineers Association, Inc. (ICEA) publishes cable standards intended to
encourage quality and uniformity for manufacturers producing telecommunications cables.
These are voluntary standards and do not prevent manufacturers from producing cables that
do not adhere to the standards.
Even though the standards do not cover all specifications for cable design, they do cover
mechanical and electrical requirements. Alternative choices are offered for type of insulation,
type of filling compound, core assembly, color code, sheath design, screened or nonscreened
core, and jacket material.
Manufacturers of OSP cables adhere to the specification requirements and standards of their
customers. In the United States, the most common designs are Bell type (see Table 3.15) and
Rural Utilities Service (RUS) type (see Table 3.30). Physical and electrical characteristics of
these designs are consistent with cable designs used worldwide. The designations used here
are for reference only and should not be regarded as a recommendation for any particular
standard.
The ICEA established a four-letter coding sequence for designating balanced twisted-pair
telecommunications cables. If required, after the four letters, a two-letter code known as the
outer protection covering designation is added.
The cable designation would be shown as follows:
•
First cable code letter—design
•
Second cable code letter—insulation type
•
Third cable code letter—conductor gauge
•
Fourth cable code letter—sheath designation
•
Pair count
•
Outer protection code
OSP Design Reference Manual, 4th edition
3-34
© 2007 BICSI®
Chapter 3: Cable Types
Cable Construction Types, continued
Insulation
OSP cables are available in many configurations. Insulation types for conductors are listed in
Table 3.12.
Table 3.12
Insulation types
Insulation Type
PIC
Composition
Solid plastic insulation, air core or filled core designs
DEPIC
Dual—expanded plastic insulation in filled core designs
Ductpic
Dual—expanded plastic insulation in air core designs
XPE-PVC
Expanded polyethylene inner layer with solid PVC skin
Pulp
Paper insulation
Foam
Single layer of expanded plastic insulation
DEPIC = Dual-expanded plastic insulated conductor
P I C = Plastic insulated conductor
XPE-PVC = Expanded polyethylene-polyvinyl chloride
© 2007 BICSI®
3-35
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Cable Construction Types, continued
Table 3.13 describes a cable code methodology used by manufacturers of Bell system cables.
This example illustrates how a cable code may be used to identify a cable’s construction. This
example breaks down the code for a 100-pair, aluminum polyethylene (ALPETH) cable with
unsoldered mechanical protection. The conductors are 26 AWG [0.41 mm (0.016 in)] bare
copper with solid plastic insulated conductor (PIC) air core with a bare aluminum shield and
polyethylene jacket. Unsoldered mechanical protection consisting of an additional steel shield
and polyethylene jacket is applied over the basic cable.
Table 3.13
Cable composition types
Cable Composition Type
Characteristics
1st Code
A
B
C
D
G
K
L
M
Cable Design
PIC filled, pulp air core, or PIC riser
PIC air core
Pulp MUP, pseudo-MUP, or high potential water resistant
PIC STEAMPETH, ductpic, or MAXPAC
High potential water resistant
Screened core
Low capacitance
Low capacitance screened core
2nd Code
B
C
D
F
G
H and K
J
L
R
Conductor Insulation Type
PE-PVC
Dual expanded polyolefin
Pulp and Tufpulp
Dual expanded polyolefin
Solid polyolefin-core filled
Solid polyolefin air core
Solid polyolefin petroleum jelly filled
Dual expanded polyolefin petroleum jelly filled
XPE-PVC expanded polyethylene and PVC
3rd Code
Gauge and Conductor Metal
Copper/Gauge
Aluminum/Gauge
B: 19
C: 17
A: 22
D: 20
M: 24
F: 22
R: 25
K: 24
T: 26
W: 28
OSP Design Reference Manual, 4th edition
3-36
© 2007 BICSI®
Chapter 3: Cable Types
Cable Construction Types, continued
Table 3.13
Cable composition types, continued
Cable Composition Type
4th Code
A
C
D
E
F
G
H
J
K
L
M
N
P
S
T
U
V
Y
Z
Sheath Designation
ALPETH
STALPETH
LOPETH
Polyjacketed lead
Polyethylene jacketed LEPETH
PAP
PASP (bonded or nonbonded)
TOLPETH
TOLPETH
Lead
LVYN
Bonded STEAMPETH
Reinforced self-support
Self-support
ARPAP
ARPASP
STEAMPETH
Bonded ASP
Bonded STALPETH
5th Code
Pair Count
6th Code
AT
BT
DA
MP
LA
SA
UM
Outer Protection Codes
Aerial type armor
Buried tape armor
Submarine, double armor
Mechanical protection
Light wire armor
Submarine, single armor
Unsoldered mechanical protection
ALPETH
ALVYN
ARPAP
ARPASP
ASP
PAP
PASP
PE
PIC
PVC
STALPETH
STEAMPETH
XPE
NOTE:
© 2007 BICSI®
Characteristics
=
=
=
=
=
=
=
=
=
=
=
=
=
Aluminum polyethylene
Aluminum polyvinyl chloride
Aluminum, resin, polyethylene, aluminum, polyethylene
Aluminum, resin, polyethylene, aluminum, steel, polyethylene
Aluminum, steel, polyethylene
Polyethylene, aluminum, polyethylene
Polyethylene, aluminum, steel, polyethylene
Polyethylene
Plastic insulated conductor
Polyvinyl chloride
Steel, aluminum, polyethylene
Aluminum, steel, polyethylene, polybutylene
Expanded polyethylene
Lead-based cables are no longer available for purchase but are still in service in
some outdoor areas.
3-37
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Cable Construction Types, continued
The information below is an example of a cable coding system. The cables are identified
by a four-letter code to simplify their designation for ordering, manufacturing, and records.
Additional information on cable coding may be found in cabling standards (e.g., ANSI/ICEA
P-61-694, Coding Guide for Copper Outside Plant and Riser Telecommunications
Cables).
To illustrate how the system works, the cable code BKMA–200–BT is identified as follows:
•
B—Air core cable with PIC insulation
•
K—Solid insulation 24 AWG [0.51 mm (0.020 in)] or 26 AWG [0.41 mm (0.016 in)]
•
M—24 AWG [0.51 mm (0.020 in)] copper
•
A—Aluminum shield
•
200—Number of pairs
•
BT—Burial tape armor
The first position of the cable code identifies the product family or design. First position
identifiers include:
•
A—Filled PIC, riser PIC
•
B—Air core PIC
•
C—High potential filled PIC
•
D—Ductpic or STEAMPETH designs
•
G—80 Percent C filling compound (early formulation, no longer used)
•
K—Internally screened core designs
•
L—Low capacitance cable
•
M—Low capacitance cable with an internal screen
•
N—PIC limited color code
•
Q—Broadband
•
T—Terminating cable (TIP) tinned copper conductors
The second position of the cable code identifies the insulation type. Second position identifiers
include:
•
B—Polyolefin with polyvinyl chloride (PVC) skin
•
C—Foam-skin insulation, air core
•
E—Foam-air core
•
F—Foam-skin insulation, filled with 65 percent filling compound
•
G—Solid polyolefin insulation, filled with 65 percent filling compound
•
H—Solid polyolefin insulation, air core (19 AWG [0.91 mm (0.036 in)] and 22 AWG
[0.64 mm (0.025 in)])
•
K—Solid polyolefin insulation, air core (24 AWG [0.51 mm (0.020 in)] and 26 AWG
[0.41 mm (0.016 in)])
•
M—Solid polyolefin insulation, filled with 80 percent filling compound
OSP Design Reference Manual, 4th edition
3-38
© 2007 BICSI®
Chapter 3: Cable Types
Cable Construction Types, continued
•
N—Foam-skin insulation, filled with 80 percent filling compound
•
R—Expanded polyolefin with PVC skin
The third position of the cable code identifies the copper conductor size. Third position
identifiers include:
•
A —22 AWG [0.64 mm (0.025 in)]
•
B—19 AWG [0.91 mm (0.036 in)]
•
H—16 AWG [1.3 mm (0.051in )]
•
M—24 AWG [0.51 mm (0.020 in)]
•
T—26 AWG [0.41 mm (0.016 in)]
•
W—28 AWG [0.32 mm (0.013 in)]
The fourth position of the cable code identifies the cable shield and jacket design. Sheath
designs considered rodent resistant are marked with an asterisk (*).
Fourth position identifiers include:
•
A—ALPETH (bare aluminum shield)
•
B—CUPETH (copper shield)
•
C—ALPETH (coated aluminum shield)
•
D—ASP* (coated aluminum shield plus coated steel armor)
•
G—PAP (jacket, aluminum shield, jacket)
•
H—PASP* (jacket, aluminum shield plus steel armor, jacket)
•
L—Lead (lead sheath)
•
M—ALVYN (coated aluminum shield, PVC jacket, indoor rated)
•
P—Reinforced self-support* (basic cable with additional steel armor)
•
S—Self-support (basic cable, aluminum shield)
•
N—Bonded ASP* (aluminum shield plus steel armor bonds to medium density
polyethylene (MDPE) jacket)
•
W—Filled ASP* (aluminum shield plus steel armor)
•
Y—Filled bonded ASP* (aluminum shield plus steel armor bonds to linear low-density
polyethylene [LLDPE] jacket)
•
Z—Air core bonded ASP* (aluminum shield plus steel armor bonds to LLDPE jacket)
When needed to accommodate extreme environments, additional layers of outer protection
may be necessary. When required, the appropriate code is added to the basic cable
designation to indicate the requested outer protection design.
Outer protection codes include:
© 2007 BICSI®
•
UM—Unsoldered mechanical protection.
•
SA—Submarine, single wire armor.
•
DA—Submarine, double wire armor.
•
AT—Aerial tape armor.
3-39
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Cable Construction Types, continued
•
BT—Burial tape armor.
•
JP—Jute.
•
RP—Rubber protection.
Common cable sheath compositions and typical applications are listed in Table 3.14.
Table 3.14
Cable sheath compositions
Sheath
Composition
Application
ALPETH
Aluminum shield,
polyethylene packet
Basic sheath
CALPETH
Coated aluminum shield,
polyethylene jacket
Basic sheath
CUPETH
Copper shield,
polyethylene jacket
Basic sheath
ASP
Inner aluminum shield plus
outer steel armor polyethylene
polyethylene jacket
Harsh environments
Rodent resistant
CASP
Inner-coated aluminum shield
plus outer-coated steel armor
polyethylene jacket
Harsh environments
Rodent resistant
GOPETH
Bi-metallic steel-based shield
polyethylene jacket
Most are rodent resistant
Consult manufacturer
Bonded ASP
Inner aluminum shield plus
outer-coated steel armor steel
bonds to the polyethylene jacket
Harsh environments
Rodent resistant
PASP
Polyethylene inner jacket,
inner aluminum shield plus
outer steel armor polyethylene
outer jacket
Harsh environments
Rodent resistant
ALVYN
Coated aluminum shield, PVC
outer jacket
UL listed CMR for indoor
OSP type electricals
OSP Design Reference Manual, 4th edition
3-40
© 2007 BICSI®
Chapter 3: Cable Types
Cable Construction Types, continued
Table 3.14
Cable sheath compositions, continued
Sheath
Composition
Application
Self-support
Aluminum shield,
support strand and cable
encased by a single jacket
(figure eight designs)
Basic sheath,
self-support aerial
Reinforced
Aluminum shield,
polyethylene inner jacket
Harsh aerial environments
Self-support
Steel armor, outer polyethelene
jacket support strand and cable
encased by the self-support outer
jacket (figure eight designs)
Rodent resistant
STALPETH
Inner aluminum shield plus
outer steel armor soldered at
shield overlap polyethylene jacket
Harsh environments
Rodent resistant
UM
Unsoldered mechanical protection
consisting of a steel shield and
jacket applied over basic cables to
provide an additional layer of
mechanical protection
Extreme environments
ALPETH
ALVYN
ASP
CASP
CALPETH
CMR
CUPETH
GOPETH
OSP
PASP
PE
PIC
PVC
STALPETH
UL®
UM
© 2007 BICSI®
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
Aluminum polyethylene
Aluminum polyvinyl chloride
Aluminum, steel, polyethylene
Coated aluminum, steel, polyethylene
Coated aluminum, polyethylene
Communications riser cable
Copper, polyethylene
Gopher-resistant, polyethylene
Outside plant
Polyethylene, aluminum, steel, polyethylene
Polyethylene
Plastic insulated conductor
Polyvinyl chloride
Steel, aluminum, polyethylene
Underwriters Laboratories Inc.®
Unsoldered mechanical
3-41
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Cable Construction Types, continued
Common sheath types and their recommended environments are shown in Table 3.15.
Table 3.15
Cable usage guide
Sheath
Aerial
Buried
Underground
Inside
ALVYN
No
No
No
Yes
ALPETH, CALPETH,
CUPETH
Yes
No
No
No
Filled ALPETH,
Filled GOPETH
Yes
Yes*
Yes
No
Self-support
Yes
No
No
No
Reinforced self-support
Yes
No
No
No
Filled self-support
Yes
No
No
No
PASP
Yes
Yes
Yes
No
Filled ASP, Filled CASP
Yes
Yes
Yes
No
STALPETH
No
No
Yes
No
Ductpic
No
No
Yes
No
*Suitable for direct burial installation in areas where the risk of damage from rodents or
environmental hazards is low. If you have questions regarding the suitability of a specific cable
design for your application, consult the manufacturer.
ALPETH
ALVYN
ASP
CASP
CALPETH
CUPETH
GOPETH
PASP
STALPETH
=
=
=
=
=
=
=
=
=
Aluminum polyethylene
Aluminum polyvinyl chloride
Aluminum, steel, polyethylene
Coated aluminum, steel, polyethylene
Coated aluminum, polyethylene
Copper, polyethylene
Gopher-resistant, polyethylene
Polyethylene, aluminum, steel, polyethylene
Steel, aluminum, polyethylene
OSP Design Reference Manual, 4th edition
3-42
© 2007 BICSI®
Chapter 3: Cable Types
Broadband Twisted-Pair Telecommunications Cable
The ICEA publishes cabling standards for broadband twisted-pair telecommunications cables
intended to encourage quality and uniformity for manufacturers producing these cables.
These are voluntary standards and do not prevent the manufacturers from producing cables
that do not adhere to the standards.
Broadband twisted-pair telecommunications cables are typically used to transport broadband
services from a remote switch to the end user. The remote switch feeding the broadband
cable usually is connected to the main switch or central office by optical fiber cable.
Broadband transmission divides the available bandwidth into multiple channels. Since many
channels are available for transmission, more than one device can transmit at a time;
therefore, simultaneous transmission can occur without collisions. Simultaneous transmission
of telephone service, computer, fax, and video are possible with broadband systems.
Broadband transmission can transfer large quantities of information at a time and is not
limited to handling only digital transmission. It also can support analog traffic, making it
capable of handling traditional voice and video signals simultaneously with data.
Broadband transmission was designed for signaling over long distances, with channel lengths
measured in kilometers (km) or miles (mi). The maximum distance allowable is a function of
the signal-to-noise ratio (SNR), protocol, and bit rate used. A network using this technology
can cover a much larger geographic area than one using baseband technology.
© 2007 BICSI®
3-43
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Plastic Insulated Conductor (PIC) Cable
Every pair of conductors in a typical PIC cable is identifiable by the color of its insulation and
the color of its binder group. Table 3.16 shows a widely accepted color code used to identify
the conductors, pairs, and groupings in the production of PIC cables.
Table 3.16
Common color code
Number
Sequence
Pair Color Code
Tip
Ring
25-Pair Group (or Subgroup)
Binder Color Code
1
White
Blue
White
Blue
2
White
Orange
White
Orange
3
White
Green
White
Green
4
White
Brown
White
Brown
5
White
Slate
White
Slate
6
Red
Blue
Red
Blue
7
Red
Orange
Red
Orange
8
Red
Green
Red
Green
9
Red
Brown
Red
Brown
10
Red
Slate
Red
Slate
11
Black
Blue
Black
Blue
12
Black
Orange
Black
Orange
13
Black
Green
Black
Green
14
Black
Brown
Black
Brown
15
Black
Slate
Black
Slate
16
Yellow
Blue
Yellow
Blue
17
Yellow
Orange
Yellow
Orange
18
Yellow
Green
Yellow
Green
19
Yellow
Brown
Yellow
Brown
20
Yellow
Slate
Yellow
Slate
21
Violet
Blue
Violet
Blue
22
Violet
Orange
Violet
Orange
23
Violet
Green
Violet
Green
24
Violet
Brown
Violet
Brown
25
Violet
Slate
NOTE:
Copper cables in excess of 900 pairs will utilize various color schemes to identify
super groups. See specific manufacturer for color-coding schemes. A super group
consists of 600 pair increments. A master group consists of 3000 pair increments.
OSP Design Reference Manual, 4th edition
3-44
© 2007 BICSI®
Chapter 3: Cable Types
Aerial Cable
The three methods for placing cable on pole lines are to:
•
Lash new cable to a new support strand.
•
Overlash new cable to an existing support strand/cable.
•
Use a self-supporting type cable that contains a support strand.
Placing new cable on an existing pole line is typically the least expensive method compared
with direct-buried and underground.
The ALPETH cable shown in Figure 3.6 is used primarily in aerial applications. The use of air
core cables in nonpressurized underground installations is discouraged in areas where moisture
is present.
ALPETH consists of:
•
Solid annealed bare copper in 19 AWG [0.91 mm (0.036 in)], 22 AWG [0.64 mm
(0.025 in)], 24 AWG [0.51 mm (0.020 in)], or 26 AWG [0.41 mm (0.016 in)].
•
Color-coded PIC insulation.
•
Pairs of conductors assembled with varying twists to minimize crosstalk.
•
Color-coded unit binders.
•
Nonhygroscopic dielectric core wrap.
•
A 0.2 mm (0.008 in) aluminum tape wrapped along the length of the cable.
•
Periodic markings on the cable that include a telephone handset icon, cable code, pair size,
AWG, date of manufacture, and sequential length marking.
Figure 3.6
ALPETH cable
Polyethylene
jacket
Solid
insulated
conductors
Core
wrap
© 2007 BICSI®
3-45
Corrugated
aluminum
shield
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Aerial Cable, continued
Dimensions for a typical ALPETH cable design are shown in Table 3.17.
Table 3.17
ALPETH cable
Pair
Count
Nominal
Outside
Diameter
mm (in)
Approximate
Weight
kg/km (lbs/kft)
BHBA - 19 AWG [0.90 mm (0.036 in)]
Pair
Count
Nominal
Outside
Diameter
mm (in)
Approximate
Weight
kg/km (lbs/kft)
BKTA - 26 AWG [0.41 mm (0.016 in)]
25
21 (0.81)
483 (324)
25
12 (0.46)
140 (94)
50
27 (1.07)
882 (592)
50
15 (0.60)
231 (155)
100
37 (1.47)
1700 (1141)
100
19 (0.73)
399 (268)
200
51 (1.99)
3226 (2166
200
24 (0.96)
721 (484)
300
61 (2.39)
4726 (3173)
300
28 (1.10)
1037 (696)
400
32 (1.24)
1345 (903)
BHAA- 22 AWG [0.64 mm (0.025 in)]
25
15 (0.61)
273 (183)
600
39 (1.52)
2005 (1346)
50
20 (0.78)
478 (321)
900
47 (1.84)
2921 (1961)
100
26 (1.03)
873 (586)
1200
53 (2.09)
3897 (2576)
200
36 (1.42)
1683 (1130)
1500
59 (2.31)
4744 (3185)
300
43 (1.69)
2446 (1642)
1800
63 (2.47)
5643 (3788
400
49 (1.91)
3195 (2145)
2100
68 (2.69)
6533 (4384)
600
58 (2.30)
4689 (3148)
2700
77 (3.05)
8316 (5583)
900
72 (2.84)
6895 (4629)
BKMA - 24 AWG [0.51 mm (0.020 in)]
25
13 (0.52)
194 (130)
50
17 (0.66)
329 (221)
100
22 (0.88)
587 (394)
200
29 (1.13)
1084 (728)
300
35 (1.38)
1616 (1085)
400
39 (1.54)
2103 (1412)
600
46 (1.83)
3066 (2058)
900
56 (2.21)
4494 (3017)
1200
66 (2.60)
5920 (3974)
1500
73 (2.88)
7329 (4920)
1800
78 (3.08)
8734 (5863
OSP Design Reference Manual, 4th edition
AWG
in
kft
kg
km
lb
mm
3-46
=
=
=
=
=
=
=
American Wire Gauge
Inch
Kilofoot
Kilogram
Kilometer
Pound
Millimeter
© 2007 BICSI®
Chapter 3: Cable Types
Self-Supporting Cable
The self-supporting cable shown in Figure 3.7 is intended for aerial applications. It is
sometimes referred to as figure eight cable. Its benefits include:
•
Lower installation costs compared with lashing non-self-supporting cable.
•
Reduced chance for corrosion of the support strand. In self-supporting cables, the support
strand becomes an integral part of the cable. The support strand is attached to the basic
cable by a web formed during the jacketing process. This makes it more suitable for
applications where corrosive atmospheres exist (e.g., industrial complexes, coastal areas).
Self-supporting cable consists of:
•
Solid annealed bare copper in 19 AWG [0.91 mm (0.036 in)], 22 AWG [0.64 mm
(0.025 in)], 24 AWG [0.51 mm (0.020 in)], or 26 AWG [0.41 mm (0.016 in)].
•
Color-coded PIC insulation.
•
Pairs of conductors assembled with varying twists to minimize crosstalk.
•
Color-coded unit binders.
•
Nonhygroscopic dielectric core wrap
•
A 0.2 mm (0.008 in) aluminum tape wrapped along the length of the cable. As an
alternative, cables larger than 20 mm (0.8 in) in diameter may utilize a copolymer coated
aluminum shield that fuses to the jacket.
•
A high-strength support strand with flooding compound, typically 6.3 mm (0.25 in)
galvanized steel.
•
A black polyethylene jacket that joins the cable and strand together.
•
Periodic markings on the cable that include code, pair size, date, length, manufacturer, and
telephone handset
Figure 3.7
Self-supporting cable
Polyethylene
jacket
Support
strand
Core
wrap
Corrugated
aluminum
Solid
insulated
conductors
© 2007 BICSI®
3-47
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Self-Supporting Cable, continued
Dimensions for a typical self-supporting cable design are shown in Table 3.18.
Table 3.18
Self-supporting cable
Part
Number
Pair
Count
BHBS - 19 AWG
Nominal
Outside Diameter
mm (in)
Minor
Major
Approximate
Weight
kg/km (lbs/kft)
[0.91 mm (0.036 in)
20-031-43
25
15 (0.60)
27 (1.07)
731 (491)
20-034-43
50
25 (0.98)
37 (1.45)
1042 (700)
BHAS - 22 AWG
[0.64 mm (0.025 in)
20-062-43
25
15 (0.58)
27 (1.05)
461 (310)
20-065-43
50
19 (0.74)
31 (1.20)
662 (445)
20-069-43
100
25 (1.00)
37 (1.47)
1049 (705)
BKMS - 24 AWG
[0.51 mm (0.020 in)
20-097-43
25
12 (0.49)
24 (0.96)
387 (260)
20-100-43
50
16 (0.62)
28 (1.09)
513 (345)
20-104-43
100
20 (0.80)
32 (1.27)
766 (515)
20-108-43
200
28 (1.09)
40 (1.56)
1250 (840)
BKTS - 26 AWG
[0.41 mm (0.016 in)
20-132-43
25
11 (0.45)
23 (0.92)
381 (256)
20-135-43
50
13 (0.52)
25 (0.97)
417 (280)
20-139-43
100
17 (0.67)
29 (1.14)
580 (390)
20-143-43
200
24 (0.93)
36 (1.40)
964 (647)
AWG
in
kft
kg
km
lb
mm
=
=
=
=
=
=
=
American Wire Gauge
Inch
Kilofoot
Kilogram
Kilometer
Pound
Millimeter
OSP Design Reference Manual, 4th edition
3-48
© 2007 BICSI®
Chapter 3: Cable Types
Self-Supporting Cable, continued
Figure 3.8 shows a reinforced version of the cable shown in Figure 3.7 and is intended for
aerial applications. It sometimes is referred to as reinforced self-supporting cable or figure
eight.
Benefits include:
•
Lower installation costs compared with lashing non–self-supporting cable.
•
Reduced chance for corrosion of the support strand. In self-supporting cables, the support
strand becomes an integral part of the cable. The support strand is attached to the basic
cable by a web formed during the jacketing process. This makes it more suitable for
applications where corrosive atmospheres exist (e.g., industrial complexes, coastal areas).
•
The addition of a steel shield and jacket that provide protection in harsh environments
It consists of:
© 2007 BICSI®
•
Solid annealed bare copper in 19 AWG [0.91 mm (0.036 in)], 22 AWG [0.64 mm
(0.025 in)], 24 AWG [0.51 mm (0.020 in)], or 26 AWG [0.41 mm (0.016 in)].
•
Color-coded PIC insulation.
•
Pairs of conductors assembled with varying twists to minimize crosstalk.
3-49
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Self-Supporting Cable, continued
•
Color-coded unit binders.
•
Nonhygroscopic dielectric core wrap.
•
A corrugated aluminum shield inside an inner polyethylene jacket, which is in turn
surrounded by corrugated steel and a flooding compound. As an alternate, cables larger
than 20 mm (0.8 in) in diameter may utilize a copolymer coated aluminum shield that
fuses to the inner jacket.
•
A high-strength support strand with flooding compound, typically 6.3 mm (0.25 in)
galvanized steel.
•
A black polyethylene jacket that joins the cable and strand together.
•
Periodic markings on the cable that include cable code, pair size, date, length,
manufacturer, and telephone handset.
Figure 3.8
Reinforced self-supporting cable
Polyethylene
Polyethylene
self-support
jacket
Support
strand
Corrugated
steel
Corrugated
aluminum
Solid
insulated
conductors
OSP Design Reference Manual, 4th edition
Plastic
core wrap
3-50
© 2007 BICSI®
Chapter 3: Cable Types
Self-Supporting Cable, continued
Dimensions for a typical reinforced self-supporting cable design are shown in Table 3.19.
Table 3.19
Reinforced self-supporting cable
Pair
Count
Nominal
Outside Diameter
mm (in)
Minor
Major
Approximate
Weight
kg/km (lbs/kft)
BHBP - 19 AWG [0.91 mm (0.036 in)
6
21 (0.83)
33 (1.3)
562 (377)
25
30 (1.18)
42 (1.66)
940 (631)
50
35 (1.38)
47 (1.87)
1420 (953)
BHAP - 22 AWG [0.64 mm (0.025 in)]
25
19 (0.75)
31 (1.22)
625 (420)
50
24 (0.93)
35 (1.39)
885 (595)
100
30 (1.18)
42 (1.64)
1332 (895)
BKMP - 24 AWG [0.51 mm (0.020 in)]
25
17 (0.67)
28 (1.12)
528 (355)
50
20 (0.80)
32 (1.25)
692 (465)
100
25 (1.0)
37 (1.45)
977 (670)
200
32 (1.25)
44 (1.73)
1562 (1050)
BKTP - 26 AWG [0.41 mm (0.016 in)]
AWG
in
kft
kg
km
lb
mm
© 2007 BICSI®
=
=
=
=
=
=
=
25
15 (0.59)
27 (1.05)
454 (305)
50
18 (0.70)
29 (1.16)
573 (385)
100
21 (0.84)
33 (1.3)
774 (520)
200
28 (1.09)
39 (1.55)
1153 (775)
300
31 (1.22)
43 (1.69)
1495 (1005)
American Wire Gauge
Inch
Kilofoot
Kilogram
Kilometer
Pound
Millimeter
3-51
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Direct-Buried Cable
Overview
Direct-buried OSP cables are subject to different and harsher environmental conditions than
those of aerial or underground (in conduit) cables. Moisture, rodent damage, and lightning are
some areas that must be addressed when installing direct-buried cables. These designs require
that the jacket’s raw material be a suitable grade polyethylene containing an antioxidant to
provide long-term stabilization and a concentration of furnace black for protection against
ultraviolet (UV) rays.
Variations to the designs shown may or may not alter the expected performance of the cable.
Product designs should be verified as suitable for the intended environment. The cable
manufacturer should be contacted for questions regarding product suitability in specific
environments.
Following guidelines address materials commonly used in direct-buried OSP environments.
Various shielding systems suitable for direct burial installations types are discussed. Variations
in designs (e.g., cellular versus solid polyolefin insulation, flat versus corrugated shields, or
coated versus bare metallic shield tapes) are not significant for most installations. The designs
discussed here are mature, proven designs and have been utilized for many years. When
installed in locations having a low to moderate risk of damage from the environment, typical
OSP cables are designed for a life expectancy of 30 years. It is common for cables to provide
trouble free service for much longer.
Direct-Buried Outside Plant (OSP) Cable Designs
Designs well suited for direct burial installations are described below.
Polyethylene, Aluminum, Steel, Polyethylene (PASP)
This air core design is suitable for pressurized direct-buried applications or may be lashed for
use in harsh aerial installations (see Figure 3.9). This design is considered rodent resistant. It
consists of:
•
Solid annealed bare copper in 19 AWG [0.91 mm (0.036 in)], 22 AWG [0.64 mm
(0.0250 in)], 24 AWG [0.51 mm (0.020 in)], or 26 AWG [0.4 mm (0.016 in)].
•
Color-coded PIC insulation.
•
Pairs of conductors assembled with varying twists to minimize crosstalk. The pairs are
assembled to form the core.
•
Color-coded unit binders.
•
Nonhygroscopic dielectric core wrap.
•
A dual shielding system applied over the inner jacket consisting of an inner, corrugated
0.2 mm (0.008 in) aluminum shield and an outer, corrugated coated 0.15 mm (0.006 in)
steel shield.
•
A black polyethylene jacket that is applied overall and bonds to the steel shield.
OSP Design Reference Manual, 4th edition
3-52
© 2007 BICSI®
Chapter 3: Cable Types
Direct-Buried Cable, continued
•
Periodic markings on the cable jacket that may include the cable code, pair count, AWG
size, date of manufacture, sequential length markings, and manufacturer code and
telephone handset icon.
Figure 3.9
PASP type design
Solid
insulated
conductors
Inner
polyethylene
jacket
Outer
polyethylene
jacket
Corrugated steel
with copolymer
adhesive coating
Corrugated
aluminum
shield
Core
wrap
© 2007 BICSI®
3-53
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Direct-Buried Cable, continued
Dimensions for a typical PASP cable design are shown in Table 3.20.
Table 3.20
PASP cables
Pair
Count
Nominal
Approximate
Outside Diameter
Weight
mm (in)
kg/km (lbs/kft)
BHBH - 19 AWG [0.91 mm (0.036 in)]
Pair
Count
Nominal
Approximate
Outside Diameter
Weight
mm (in)
kg/km (lbs/kft)
BKTH - 26 AWG [0.41 mm (0.016 in)]
25
24 (0.95)
611 (410)
25
15 (0.59)
212 (142)
50
30 (1.18)
1062 (713)
50
18 (0.70)
325 (218)
100
40 (1.58)
1962 (1317)
100
22 (0.87)
526 (353)
200
56 (2.20)
3611 (2424)
200
28 (1.09)
898 (603)
300
66 (2.60)
5209 (3497)
300
32 (1.25)
1283 (861)
400
36 (1.42)
1647 (1106)
BHAH - 22 AWG [0.64 mm (0.025 in)]
25
19 (0.77)
371 (249)
600
42 (1.65)
2346 (1575)
50
23 (0.91)
611 (410)
900
50 (1.97)
3347 (2347)
100
30 (1.18)
1062 (713)
1200
57 (2.25)
4335 (2910)
200
41 (1.60)
1965 (1319)
1500
63 (2.49)
5306 (3562)
300
47 (1.87)
2805 (1883)
1800
67 (2.65)
6282 (4217)
400
53 (2.10)
3612 (2475)
2100
79 (3.10)
7214 (4843)
600
63 (2.49)
5222 (3506)
2400
80 (3.12)
8141 (5465)
900
75 (2.97)
7567 (5080)
2700
80 (3.30)
8706 (5850)
1200
86 (3.40)
9833 (6601)
BKMH - 24 AWG [0.51 mm (0.020 in)]
25
17 (0.66)
277 (186)
50
21 (0.81)
439 (295)
100
26 (1.01)
740 (493)
200
33 (1.30)
1336 (895)
300
39 (1.52)
1904 (1278)
400
44 (1.77)
2437 (1626)
600
52 (2.04)
3493 (2345)
900
61 (2.40)
5035 (3380)
1200
69 (2.70)
6557 (4402)
1500
78 (3.07)
8026 (5388)
1800
85 (3.35)
9474 (6360)
2100
91 (3.58)
10917 (7329)
OSP Design Reference Manual, 4th edition
AWG
in
kft
kg
km
lb
mm
3-54
=
=
=
=
=
=
=
American Wire Gauge
Inch
Kilofoot
Kilogram
Kilometer
Pound
Millimeter
© 2007 BICSI®
Chapter 3: Cable Types
Direct-Buried Cable, continued
Filled Aluminum, Steel, Polyethylene (ASP)
This cable design has a fully filled core and a dual shielding system (see Figure 3.10). The
insulation design may be a single, solid layer of polyolefin (PIC) or dual-expanded plastic
insulated conductor (DEPIC). The shields may be bare or coated and may be applied flat or
with corrugations. These designs require that the jacket’s raw material be a suitable grade
polyethylene containing an antioxidant to provide long-term stabilization and a concentration of
furnace black for protection against UV rays. These shield designs are considered rodent
resistant.
Examples of other functionally equal designs include:
•
Filled bonded ASP.
•
Filled coated aluminum, coated steel, polyethylene (CACSP).
Shown in Figure 3.10, these designs are suitable for direct-buried applications. These designs
consist of:
•
Solid annealed bare copper in 19 AWG [0.91 mm (0.036 in)], 22 AWG [0.64 mm
(0.250 in)], 24 AWG [0.51 mm (0.020 in)], or 26 AWG [0.4 mm (0.016 in).
•
Color-coded PIC or DEPIC insulation.
•
Pairs assembled to form the core.
•
Color-coded unit binders.
•
Filled core.
•
Nonhygroscopic dielectric core wrap.
•
A dual shielding system consisting of an inner, corrugated 0.2 mm (0.008 in) aluminum
shield and an outer, corrugated 0.15 mm (0.006 in) steel shield.
•
Flooding compound applied over the core wrap and each shield tape.
•
A black polyethylene jacket applied overall.
•
Periodic markings on the cable jacket that may include the cable code, pair count, AWG
size, date of manufacture, sequential length markings, and manufacturer code and
telephone handset icon.
For answers regarding the suitability of alternate designs, the cable manufacturer should be
contacted.
© 2007 BICSI®
3-55
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Direct-Buried Cable, continued
Filled Bonded Aluminum, Steel, Polyethylene (ASP)
Filled bonded ASP designs are the same as the above except:
•
The unflooded, coated corrugated 0.15 mm (0.006 in) steel shield bonds to the jacket.
Filled Coated Aluminum, Coated Steel, Polyethylene (CACSP)
Filled CACSP designs are the same as the above except:
•
There is a dual shielding system consisting of an inner, coated corrugated 0.2 mm
(0.008 in) aluminum shield and an outer, coated corrugated 0.15 mm (0.006 in) steel
shield.
Figure 3.10
Filled ASP type cable
Polyethylene
jacket
Conductor
filling
compound
Corrugated
coated steel
Foam skin
insulated
conductors
OSP Design Reference Manual, 4th edition
Core
wrap
3-56
Corrugated
coated
aluminum
© 2007 BICSI®
Chapter 3: Cable Types
Direct-Buried Cable, continued
Dimensions for a typical filled ASP cable design are shown in Table 3.21.
Table 3.21
Filled ASP type cable
Nominal
Outside
Diameter
mm (in)
Pair
Count
Approximate
Weight
kg/km (lbs/kft)
Pair
Count
Nominal
Outside
Diameter
mm (in)
Approximate
Weight
kg/km (lbs/kft)
ANMW - 24 AWG [0.51 mm (0.020 in)]
ANBW - 19 AWG [0.91 mm (0.036 in)]
25
23 (0.91)
666 (447)
25
15 (0.59)
276 (185)
50
29 (1.16)
1168 (784)
50
18 (0.70)
450 (302)
100
40 (1.58)
2161 (1451)
100
24 (0.95)
767 (515)
200
55 (2.16)
4070 (2732)
200
32 (1.25)
1363 (915)
300
66 (2.60)
5921 (3975)
300
38 (1.50)
1978 (1328)
400
42 (1.64)
2553 (1714)
ANAW - 22 AWG [0.64 mm (0.025 in)]
25
18 (0.70)
386 (259)
600
51 (2.00)
3702 (2485)
50
22 (0.87)
646 (434)
900
60 (2.38)
5386 (3616)
100
29 (1.16)
1137 (763)
1200
69 (2.70)
7177 (4818)
200
38 (1.50)
2111 (1417)
1500
77 (3.04)
8851 (5944)
300
45 (1.75)
3051 (2048)
1800
83 (3.28)
10,528 (7068)
400
52 (2.04)
3968 (2664)
2100
89 (3.50)
12,127 (8141)
600
63 (2.49)
5774 (3876)
900
77 (3.04)
8440 (5666)
25
13 (0.52)
210 (141)
1200
88 (3.46)
11,132 (7473)
50
16 (0.63)
329 (221)
100
20 (0.80)
535 (359)
200
27 (1.06)
935 (628)
300
32 (1.25)
1311 (880)
400
36 (1.42)
1712 (1449)
600
42 (1.65)
2444 (1641)
900
52 (2.04)
3547 (2381)
1200
59 (2.34)
4701 (3156)
1500
64 (2.50)
5786 (3884)
1800
70 (2.75)
6857 (4603)
2100
76 (3.00)
7928 (5322)
2400
78 (3.07)
8990 (6035)
2700
84 (3.30)
10,049 (6746)
AWG
in
kft
kg
km
lb
mm
=
=
=
=
=
=
=
ANTW - 26 AWG [0.40 mm (0.016 in)]
American Wire Gauge
Inch
Kilofoot
Kilogram
Kilometer
Pound
Millimeter
© 2007 BICSI®
3-57
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Direct-Buried, continued
Some of the more common types of filled solid ALPETH cables are described in Table 3.22.
Table 3.22
PE 39—Filled solid ALPETH cable
Pair
Count
Nominal
Outside
Diameter
mm (in)
Approximate
Weight
kg/km (lbs/kft)
Pair
Count
Nominal
Outside
Diameter
mm (in)
Approximate
Weight
kg/km (lbs/kft)
24 AWG [0.51 mm (0.020 in)]
19 AWG [0.91 mm (0.036 in)]
6
16 (0.63)
229 (154)
6
10 (0.39)
106 (71)
12
20 (0.80)
390 (262)
12
13 (0.51)
161 (108)
25
25 (1.00)
714 (479)
25
16 (0.63)
268 (180)
50
35 (1.39)
1332 (894)
50
21 (0.81)
462 (310)
100
48 (1.90)
2511 (1686)
100
27 (1.06)
827 (555)
200
35 (1.39)
1560 (1047)
22 AWG [0.64 mm (0.025 in)]
6
12 (0.47)
139 (93)
300
42 (1.64)
2258 (1516)
12
15 (0.59)
222 (149)
400
48 (1.90)
2949 (1980)
25
19 (0.75)
386 (259)
600
59 (2.34)
4321 (2901)
50
25 (1.00)
681 (457)
900
72 (2.83)
6355 (4266)
100
33 (1.30)
1244 (835)
1200
79 (3.10)
8310 (5579)
200
45 (1.75)
2395 (1608)
1500
88 (3.46)
9902 (6655)
300
53 (2.10)
3492 (2344)
1800
96 (3.78)
12143 (8159)
400
61 (2.40)
4586 (3079)
600
74 (2.90)
6748 (4530)
900
88 (3.50)
9948 (6678)
AWG
in
kft
kg
km
lb
mm
=
=
=
=
=
=
=
American Wire Gauge
Inch
Kilofoot
Kilogram
Kilometer
Pound
Millimeter
OSP Design Reference Manual, 4th edition
3-58
© 2007 BICSI®
Chapter 3: Cable Types
Underground Cable
Overview
OSP cables installed in underground conduit are often referred to as underground cables.
Underground conduit provides a protected environment for the cable eliminating the need for
physically robust shielding systems required for direct-buried installations.
These cable designs may utilize solid PIC or DEPIC style insulation. They may utilize coated
or bare metal tapes applied flat or with corrugations. They must be capable of providing
adequate mechanical protection for this environment. A filled cable design is highly
recommended for this environment as moisture continues to be a concern. Nearly all conduits
contain water or will contain water at some point. Designs well suited for underground conduit
installations are described below.
Underground Conduit Cable Designs
Filled ALPETH type designs are suitable for underground conduit installations (see
Figure 3.11). They also may be lashed and used aerially or may be buried directly in areas
where there is a low risk of damage from rodents or other environmental hazards. These
products are not considered rodent resistant.
These designs consist of:
© 2007 BICSI®
•
Solid annealed bare copper in 19 AWG [0.91 mm (0.036 in)], 22 AWG [0.64 mm
(0.0250 in)], 24 AWG [0.51 mm (0.020 in)], or 26 AWG [0.4 mm (0.016 in).
•
Color-coded PIC or DEPIC insulation.
•
Pairs of conductors assembled with varying twists to minimize crosstalk. The pairs are
assembled to form the core.
•
Color-coded unit binders.
•
Filled core.
•
Nonhygroscopic dielectric core wrap.
•
A corrugated 0.2 mm (0.008 in) aluminum shield applied over the core wrap. Optional
shield types for this design include 0.13 mm (0.005 in) copper.
•
A flooding compound that may be applied over the core wrap and shield tape
•
A black polyethylene jacket applied overall.
•
Periodic markings on the cable jacket that may include the cable code, pair count, AWG
size, date of manufacture, sequential length markings, and manufacturer code and
telephone handset icon.
3-59
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Underground Cable, continued
Figure 3.11
Filled ALPETH type cable
Polyethylene
jacket
Filling
compound
Solid
insulated
conductors
Coated
corrugated
aluminum
Core
wrap
OSP Design Reference Manual, 4th edition
3-60
© 2007 BICSI®
Chapter 3: Cable Types
Underground Cable, continued
Dimensions for typical filled ALPETH cable designs are shown in Table 3.23.
Table 3.23
Filled ALPETH type cable
Pair
Count
Nominal
Outside Diameter
mm (in)
Approximate
Weight
kg/km (lbs/kft)
DCAZ-22 AWG [0.64 mm (0.025 in)]
25
55 (2.16)
4561 (3065)
50
65 (2.55)
6658 (4474)
100
73 (2.87)
8734 (5869)
600
45 (1.75)
2982 (1997)
900
51 (2.00)
4308 (2895)
1200
59 (2.34)
5645 (3793)
1500
65 (2.55)
6976 (4683)
2400
84 (3.30)
10884 (7307)
600
37 (1.45)
1959 (1316)
900
43 (1.69)
2825 (1898)
1200
46 (1.80)
3663 (2459)
1500
52 (2.04)
4499 (3020)
1800
56 (2.20)
5333 (3580)
2100
62 (2.45)
6166 (4143)
2400
65 (2.55)
6988 (4691)
2700
70 (2.75)
7822 (5256)
3000
71 (2.80)
8635 (5797)
3600
76 (3.00)
10266 (6892)
4200
83 (3.25)
11890 (7982)
DCMZ-24 AWG [0.51 mm (0.020 in)
DCTZ-26 AWG [0.41 mm (0.016 in)]
AWG
in
kft
kg
km
lb
mm
© 2007 BICSI®
=
=
=
=
=
=
=
American wire gauge
Inch
Kilofoot
Kilogram
Kilometer
Pound
Millimeter
3-61
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Underground Cable, continued
Bonded Steel, Aluminum, Polyethylene (STALPETH)
Bonded STALPETH is an air core design often referred to as ductpic (see Figure 3.12). This
special use design may be considered for underground conduit installations where large pair
count cable is required and conduit space is limited. This cable design is available in limited
pair count and copper sizes. This design is considered rodent resistant.
These designs consist of:
•
Solid annealed bare copper in 24 AWG [0.51 mm (0.020 in)], or 26 AWG [0.4 mm
(0.016 in).
•
Color-coded DEPIC insulation.
•
Pairs of conductors assembled with varying twists to minimize crosstalk. Pairs are
assembled to form the core.
•
Color-coded unit binders
•
Nonhygroscopic dielectric core wrap
•
A dual shielding system consisting of an inner, corrugated 0.2 mm (0.008 in) aluminum
shield and an outer, coated and corrugated 0.15 mm (0.006 in) steel shield.
•
A black polyethylene jacket that is applied overall and bonds to the steel shield.
•
Periodic markings on the cable jacket that may include the cable code, pair count, AWG
size, date of manufacture, sequential length markings, and manufacturer code and
telephone handset icon.
Availability may be limited.
Figure 3.12
Underground (ductpic) cable
Extruded
polyethylene
jacket
Corrugated
aluminum
shield
Foam skin
insulated
conductors
Copolymer coated
corrugated steel
Core
wrap
OSP Design Reference Manual, 4th edition
3-62
© 2007 BICSI®
Chapter 3: Cable Types
Underground Cable, continued
Dimensions for a typical bonded STALPETH/ductpic cable design are shown in Table 3.24.
Table 3.24
Bonded STALPETH/ductpic cable
Pair
Count
Nominal
Outside Diameter
mm (in)
Approximate
Weight
kg/km (lbs/kft)
DCMZ-24 AWG [0.51 mm (0.020 in)
600
45 (1.75)
2982 (1997)
900
51 (2.00)
4308 (2895)
1200
59 (2.31)
5645 (3793)
1500
65 (2.55)
6976 (4683)
2400
84 (3.30)
10884 (7307)
600
37 (1.45)
1959 (1316)
900
43 (1.69)
2825 (1898)
1200
46 (1.80)
3663 (2459)
1500
52 (2.04)
4499 (3020)
1800
56 (2.20)
5333 (3580)
2100
62 (2.45)
6166 (4143)
2400
65 (2.55)
6988 (4691)
2700
70 (2.75)
7822 (5256)
3000
71 (2.80)
8635 (5797)
3600
76 (3.00)
10266 (6892)
4200
83 (3.25)
11890 (7982)
DCTZ-26 AWG [0.41 mm (0.016 in)]
AWG
in
kft
kg
km
lb
mm
© 2007 BICSI®
=
=
=
=
=
=
=
American wire gauge
Inch
Kilofoot
Kilogram
Kilometer
Pound
Millimeter
3-63
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Underground Cable, continued
Outside Plant (OSP) Copper Designs, Internally Screened Cables
Air Core Screened Cable
Shown in Figure 3.13, air core screened cables are designed for digital applications. In this
design, the core is bisected by one or more internal aluminum screen. Dividing the core into
two halves allows the signals to be segregated. One half of the core is designated for sending
signals, and the other half is for receiving signals.
These designs often include extra pairs used for testing or as special use pairs for specialized
equipment. This cable design typically is used in lashed aerial installations.
These designs consist of:
•
Solid annealed bare copper in 22 AWG [0.64 mm (0.025 in)].
•
Color-coded PIC insulation.
•
Pairs of conductors assembled with varying twists to minimize crosstalk. Pairs are
assembled to form the core.
•
Color-coded unit binders.
•
A 0.10 mm (0.004 in) aluminum internal screen.
•
Nonhygroscopic dielectric core wrap.
•
A dual shielding system consisting of an inner, corrugated 0.2 mm (0.008 in) aluminum
shield and an outer, coated and corrugated 0.15 mm (0.006 in) steel shield. (Other shield
systems although less common are sometimes used.)
•
A black polyethylene jacket that is applied overall and bonds to the steel shield.
•
Periodic markings on the cable jacket that may include the cable code, pair count, AWG
size, date of manufacture, sequential length markings, and manufacturer code and
telephone handset.
This once common design has been replaced in new installations by fiber.
OSP Design Reference Manual, 4th edition
3-64
© 2007 BICSI®
Chapter 3: Cable Types
Underground Cable, continued
Figure 3.13
Air core screened cable
Aluminum
Z-screen
Inner
polyethylene
jacket
Solid
insulated
conductors
Aluminum
screen
Outer
polyethylene
jacket
Corrugated steel
with copolymer
adhesive coating
Cable
core
Corrugated
aluminum
shield
Core
wrap
Filled Screened Cable
Shown in Figure 3.14, filled screened cables are designed for digital applications. The core of
this design is bisected by an internal aluminum screen (or screens). Dividing the core into two
halves allows the signals to be segregated. One half of the core is designated for sending
signals, and the other half is for receiving signals.
These designs often include extra pairs used for testing or as special use pairs for specialized
equipment. Depending on the shielding system, this cable design may be used in underground
or direct burial installations.
These designs consist of:
© 2007 BICSI®
•
Solid annealed bare copper in 22 AWG [0.64 mm (0.025 in)].
•
Color-coded PIC insulation.
•
Pairs of conductors assembled with varying twists to minimize crosstalk. Pairs are
assembled to form the core.
•
Color-coded unit binders
•
Filled core.
•
A 0.10 mm (0.004 in) aluminum internal screen.
3-65
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Underground Cable, continued
•
Nonhygroscopic dielectric core wrap.
•
A dual shielding system consisting of an inner, corrugated 0.2 mm (0.008 in) aluminum
shield and an outer, coated and corrugated 0.15 mm (0.006 in) steel shield. (Other shield
systems although less common are sometimes used.)
•
A flooding compound that may be applied over the core and shield interfaces.
•
A black polyethylene jacket applied overall.
•
Periodic markings on the cable jacket that may include the cable code, pair count, AWG
size, date of manufacture, sequential length markings, and manufacturer code and
telephone handset icon.
This once common design has been replaced in new installations by fiber.
Figure 3.14
Filled screened cable
Aluminum
Z-screen
Polyethylene
jacket
Conductor
filling compound
Corrugated
steel
Corrugated
aluminum
shield
Core
wrap
Cable
core
OSP Design Reference Manual, 4th edition
3-66
© 2007 BICSI®
Chapter 3: Cable Types
Aerial Drop Wire
Aerial drop wire extends the telecommunications circuit from an aerial terminal to a building/
residential entrance protector or network interface. Types of manufactured aerial drop wire
may include:
•
Aerial drop wire—Used for runs less than 213 m (700 ft).
•
Aerial distribution wire—Used for runs over 213 m (700 ft).
Aerial drop wire is typically:
•
22 AWG [0.64 mm (0.025 in)].
•
2, 3, 5, and 6 pair.
•
Air core or filled.
•
Foil or metallic shield (optional).
•
Equipped with support strand or supported by its own sheath.
•
Protected by black outer jacket.
Direct-Buried Service Wire
Direct-buried service wire extends the telecommunications circuit from a direct-buried
terminal to a building/residential entrance protector or network interface. Types of directburied service wire manufactured include:
•
Direct-buried service wire—Used for runs less than 213 m (700 ft).
•
Direct-buried distribution wire—To be used for runs over 213 m (700 ft).
Direct-buried service wire is typically:
© 2007 BICSI®
•
22 AWG [0.64 mm (0.025 in)] (optional 19 AWG [0.91 mm (0.036 in)]).
•
2, 3, 5, and 6 pair.
•
Filled.
•
Supported by metallic shield (optional).
•
Protected by black outer jacket.
3-67
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Coaxial Cabling
Cable Selection
Coaxial cable is capable of delivering full-motion video, digital, and analog signals with fullduplex transmission of data, as well as voice, over long and short distances (see Figure 3.15).
NOTE:
Customer requirements should be determined before proceeding with the design.
To determine the size of coaxial cable for any application, it is necessary to define and
understand cable properties. By definition, a coaxial cable consists of two metallic conductors
sharing the same axis, hence the term coaxial. Coaxial cable has a metallic center conductor,
coaxially positioned within an outer metallic conductor, with the two separated by a dielectric
(nonconducting) material.
Figure 3.15
Coaxial cable
Outer
sheath
Aluminum outer
conductor
Center
conductor
Dielectric
adhesive
Dielectric
When determining the size and type of coaxial cable, the two major factors a designer has to
consider are attenuation margin and cost.
OSP Design Reference Manual, 4th edition
3-68
© 2007 BICSI®
Chapter 3: Cable Types
Mechanical Factors
Coaxial cable is available in many different physical configurations, with variations in center
conductors, dielectric materials, outer conductors, and jackets. Coaxial cable also comes in
semirigid, flexible, and super flexible styles, with differing loss characteristics for each.
Coaxial cable sizes range from 6.3 mm (0.25 in) round and can be as large as 127 mm (5 in).
Typical sizes are 9.5 mm (0.375 in); 12.7 mm (0.5 in); 16 mm (0.63 in); 22 mm (0.87 in);
32 mm (1.25 in); and 41 mm (1.6 in).
The following describes the different environmental conditions and the types of coaxial cable
commonly used.
Center Conductor
The center conductor may be solid, stranded, or tubular. Coaxial cables with solid center wires
or tubes typically will have the lowest attenuation factor but are the least flexible. Stranded
center wires will afford more flexibility but increased attenuation. Tube construction allows for
a lighter weight cable for larger overall outer diameters.
Dielectric
The dielectric provides the necessary spacing between the inner (or center) and outer
conductors. The spacing allows for propagation of the signal down the coaxial line. The
dielectric materials range from air to air and foam (cellular or extruded polyethylene).
Extruded polyethylene is the cheapest, most commonly used dielectric that provides high
strength combined with a low dielectric constant and good attenuation margin at low
temperatures.
Outer Conductor
The outer conductor, or shield, can be either metal braid or corrugated or straight tubing.
Braiding is more common for flexible applications and can come in single or adjacent
configurations. Two adjacent shields offer better shielding. The braids generally are made
from copper, tinned-copper, or silver-plated copper. Tubular construction is used where
strength and a high degree of shielding are required along with low signal attenuation.
Jackets
Insulating jackets protect the coaxial cable. Different jacket materials protect the cable from
corrosion and inclement weather and come in varying temperature ranges from –55 °Celsius
(C [(–67 °Fahrenheit [F])]) and as high as 250 °C (482 °F). Each material has its own
classifications for environment settings and soil and air conditions. The designer should consult
with the client to determine the specific application and choose the correct jacket accordingly.
© 2007 BICSI®
3-69
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Electrical Factors
A designer has to consider the following electrical characteristics when choosing coaxial
cable:
•
Capacitance
•
Inductance
•
Impedance
•
Bandwidth
•
Direct current (dc) resistance
•
Attenuation
•
Structural return loss
Relative capacitance and inductance from differing cable sizes do not vary much.
For example, a 12.7 mm (0.5 in) foam dielectric coaxial cable has a capacitance of
23.1 picofarads per foot (pF/ft), while 32 mm (1.25 in) foam dielectric coaxial cable has a
capacitance of 22.9 pF/ft. Similarly, the relative inductance for 12.7 mm (0.5 in) and 32 mm
(1.25 in) coaxial cable is 0.058 microhenrys per foot (H/ft) and 0.056 H/ft, respectively.
The characteristic input impedance for coaxial cables from the manufacturer is typically either
50 ohm or 75 ohm. The designer needs to verify the application with the client to determine
which input impedance is best.
As mentioned before, the velocity of propagation, or phase velocity, is expressed as a
proportion of the speed of light in a vacuum and is inversely proportional to the square root of
the effective dielectric constant:
Ideally, the ratio would be 100 percent, but realistically, manufacturers provide coaxial cables
in the 85 to 90 percent range.
The two most pertinent factors that change from one cable size to another are dc resistance
and attenuation. These specifications are easily attainable from manufacturers.
The cable manufacturer’s information usually lists dc resistance three ways—center
conductor, outer conductor, and loop resistance. This information, along with cable lengths and
amplifiers, is valuable in calculating the powering of the network. Power calculations are
usually made after the cabling system layout is complete. The cable dc loop resistance is the
specification used for this calculation.
Attenuation is a phenomenon that is dependent on the cable size, the dielectric material, length
of cable, and frequency of the system. The longer the length of cable, the greater the
attenuation. The higher the frequency, the greater the attenuation. For a given dielectric, the
larger the cable OD, the lower the attenuation. Attenuation is the key factor that a designer
must keep in mind when considering coaxial cable. It determines how often the signal has to
be amplified in the network.
OSP Design Reference Manual, 4th edition
3-70
© 2007 BICSI®
Chapter 3: Cable Types
Electrical Factors, continued
The attenuation factor can be expressed as:
α
=
B • f + A • √f
Where:
A is the conductor loss;
B is the dielectric loss; and,
f is the operating frequency.
For typical rigid copper coaxial cables, there are practically no dielectric losses, so:
α
=
0.433/Z0 • (1/D + 1/d) • √f
Where:
Z0 is the characteristic impedance;
D is the diameter of the outer conductor; and,
d is the diameter of the inner conductor, all in inches.
© 2007 BICSI®
3-71
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Aerial Applications
See Figure 3.16 for examples of bare aluminum, jacketed, and self-support aerial coaxial
cables:
•
Bare aluminum—This is the simplest type of coaxial cable. All others are variations of
this type. It consists of a seamless aluminum tube (outer conductor) foam dielectric and
center conductor, which is usually made of copper clad aluminum or steel. This cable is
best used in moderate climates.
•
Jacketed—This is the same as the bare aluminum cable except that it is encased in a high
molecular weight polyethylene outer jacket. This cable is best used in hostile climates. It
offers protection from salt oxidation and ice.
•
Self-support—This cable is identical to jacketed cable except that there is a supporting
strand wire fused to the outer jacket. The purpose of this wire is to eliminate the hanging
of strand as well as the lashing of cable to the strand. This type of cable lowers plant
construction costs but inhibits the future possibility of overlashing a second cable onto the
existing constructed plant.
Figure 3.16
Aerial coaxial cables
Bare aluminum
Jacketed
Self-support
OSP Design Reference Manual, 4th edition
3-72
© 2007 BICSI®
Chapter 3: Cable Types
Direct-Buried Applications
Flooded and armored cables are known as semirigid (hard-line) cables:
•
Flooded—This cable is a jacketed cable with a “flooding” compound between the jacket
and the aluminum outer conductor. The flooding offers protection from nicks and tears of
the outer jacket during the construction process.
•
Armored/flooded—This cable is a flooded cable with a metallic armor encasing the jacket,
an additional layer of flooding compound, and a final outer polyethylene jacket (see Figure
3.17). This protective covering provides additional defense from the construction process
as well as rodents and cuts from digging and excavation.
Figure 3.17
Armored cable
Armored
These cables typically are available in the following sizes: 12.7 mm (0.5 in), 16 mm (0.63 in),
22 mm (0.87 in), 32 mm (1.25 in), and 41 mm (1.6 in). Larger sizes are available but are very
difficult to acquire and are not widely used. Coaxial is measured by the OD of the aluminum
or copper outer conductor and not the jacket (see Table 3.25).
© 2007 BICSI®
3-73
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Direct-Buried Applications, continued
Table 3.25
Cable attenuation at VSWR = 1.0, 50 ohm foam dielectric and ambient 20 °C (68 °F)
Diameter (OD)
mm (in)
450 MHz
dB/100 m
(dB/100 ft)
1000 MHz
dB/100 m
(dB/100 ft)
2000 MHz
dB/100 m
(dB/100 ft)
12.7 (0.5)
4.75 (1.45)
7.28 (2.22)
10.7 (3.25)
16 (0.63)
3.46 (1.05)
5.38 (1.64)
8.02 (2.44)
22 (0.87)
2.65 (0.808)
4.12 (1.25)
6.11 (1.86)
32 (1.25)
1.87 (0.571)
2.94 (0.897)
4.43 (1.35)
41 (1.6)
1.53 (0.467)
2.43 (0.742)
3.71 (1.13)
dB
ft
in
m
MHz
mm
OD
=
=
=
=
=
=
=
Decibel
Foot
Inch
Meter
Megahertz
Millimeter
Outside diameter
Design Criteria
Selection of different types of cables should be based on the losses per unit length for specific
point-to-point distances, untapped and unspliced. Table 3.26 shows the attenuation of various
size cables at the given frequencies expressed per kilometer or per mile.
Table 3.26
Coaxial attenuation at 20 °C (68 °F) over long distances
Diameter (OD)
mm (in)
450 MHz
dB/100 m
(dB/100 ft)
1000 MHz
dB/100 m
(dB/100 ft)
2000 MHz
dB/100 m
(dB/100 ft)
12.7 (0.5)
47.5 (76.6)
72.8 (117.2)
107 (171.6)
16 (0.63)
34.6 (55.4)
53.8 (86.6)
80.2 (128.8)
22 (0.87)
26.5 (42.7)
41.2 (66.0)
61.1 (98.2)
32 (1.25)
18.7 (30.2)
29.4 (47.4)
44.3 (71.3)
41 (1.6)
15.3 (24.7)
24.3 (39.1)
37.1 (59.7)
dB
in
km
MHz
mi
mm
OD
=
=
=
=
=
=
=
Decibel
Inch
Kilometer
Megahertz
Mile
Millimeter
Outside diameter
OSP Design Reference Manual, 4th edition
3-74
© 2007 BICSI®
Chapter 3: Cable Types
Design Criteria, continued
Although cables with a smaller diameter are less expensive, their comparatively higher loss
may result in added expense for network equipment such as amplifiers. To minimize network
noise, it is desirable to limit the number of amplifiers per backbone run.
The designer also should keep in mind that if the network is to be of significant size, two sizes
of cable could be selected. Use a larger size (22 mm [0.87 in] or larger) to trunk the signal
into the service areas. Use a smaller cable (16 mm [0.63 in] or smaller) as feeders to tap into
and deliver the signals to the terminations. This is known as trunk and feeder architecture (see
Figure 3.18).
Figure 3.18
Trunk and feeder system
Return
Trunk
Feeder
Subscriber Service Drops
The subscriber service drop is the last and most important piece of any network. It is also the
final piece of cable that a designer has to choose. Drop cable is different from semirigid
(hard-line) coaxial cable in that it is much smaller, more flexible, and easier to handle. It also
has higher attenuation. Subscriber service drop is compared with that of semirigid.
Sizes and types of drop cable are listed in Table 3.27. Drop cable is similar to semirigid in its
makeup, with a few exceptions. The outer conductor of drop wire is not a thick seamless
aluminum tube, but a thin, flexible, aluminum foil. The foil is wrapped with aluminum braid,
used for shielding, which is available in different coverage percentages. There is also tri shield
or quad shield, sometimes known as super shield, drop cable. This quad shield type of cable
has an additional foil wrap around the aluminum braid and a second aluminum braid around the
second foil wrap and should be used in two-way applications (see Figure 3.19).
Drop service cables are not designated by the outer conductor size, but by a specific joint
Army Navy (JAN) designation such as Series 6 and Series 11. Drop service wires also are
available in self-supporting and filled versions just like the semirigid coaxial cables.
© 2007 BICSI®
3-75
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Subscriber Service Drops, continued
Figure 3.19
Standard shield and quad shield construction (drop cable)
Center conductor
Center conductor
Dielectric
Dielectric
Bonded aluminum foil shield
Bonded aluminum foil shield
Aluminum-braided shield
Aluminum-braided shield
Jacket
Aluminum foil shield
Aluminum-braided shield
Jacket
Super shield (quad) construction
Standard shield construction
Table 3.27
Drop cable and attenuation
Size
(JAN)
450 MHz
dB/100 m
(dB/100 ft)
550 MHz
dB/100 m
(dB/100 ft)
750 MHz
dB/100 m
(dB/100 ft)
Series 6
14.40 (4.40)
16.10 (4.90)
18.50 (5.65)
Series 11
9.02 (2.75)
10.00 (3.04)
12.00 (3.65)
dB
ft
JAN
m
MHz
=
=
=
=
=
Decibel
Foot
Joint Army Navy
Meter
Megahertz
OSP Design Reference Manual, 4th edition
3-76
© 2007 BICSI®
Chapter 3: Cable Types
Subscriber Service Drops, continued
Sizes and types of drop cable at maximum drop length are listed in Table 3.28.
Table 3.28
Drop cable and attenuation at maximum drop length
Size
(JAN)
450 MHz
dB/100 m
(dB/100 ft)
550 MHz
dB/100 m
(dB/100 ft)
Series 6
54.0 (177)
7.8
8.7 10
Series 11
74.1 (243)
7.5
8.3 10
dB
ft
JAN
m
MHz
=
=
=
=
=
750 MHz
dB/100 m
(dB/100 ft)
Decibel
Foot
Joint Army Navy
Meter
Megahertz
A designer should consider the following factors:
•
Amplifier link budgets
•
Amplifier cascade limitations
•
Environmental factors
•
Drop length
•
Signal level minimums to the house
•
Price
With the information provided, a designer should be able to decide what types and sizes of
cable will work best with the network.
Table 3.29 shows losses for splitters and 75 ohm coaxial cables. The losses shown are
generally accepted generic averages (they will vary by manufacturer) and can be used in
most general infrastructure designs to calculate the link loss.
© 2007 BICSI®
3-77
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Subscriber Service Drops, continued
Table 3.29
Generic impedance for video infrastructure components
Description
550 MHz
1000 MHz
Series 6 (RG 6) at 30.5 m (100 ft)
–5 dB
–6.5 dB
Series 11 (RG 11) at 30.5 m (100 ft)
–3 dB
–4.25 dB
Two-way splitter*
–3.5 dB
–4.75dB
Three-way splitter*
–6.0 dB
–7 dB
Four-way splitter*
–7.0 dB
–8.25 dB
Six-way splitter*
–9.5 dB
–10.5 dB
Eight-way splitter*
–11 dB
–12 dB
Connectors and couplers
–0.1 dB
–0.15 dB
* Isolation between ports on all splitters should never be less than -20 dB. Isolation of -30 dB
or greater would be best. This isolation factor becomes increasingly important as the number
of daisy-chained splitters are increased.
dB = Decibel
ft = Foot
m = Meter
MHz = Megahertz
R G = Radio grade
The following are useful rules of thumb to use in analog video infrastructure design:
•
Amplifiers should be added to compensate for losses. For CATV systems, link losses of
–10 to –13 dB should not need amplification, assuming the CATV input signal handoff is
of sufficient strength (see Figure 3.20).
•
When installing an amplifier, it should be sized to compensate for calculated losses and
avoid overdriving the signal. Overdriving a system can damage equipment. When possible,
an amplifier with variable gain and slope control should be selected as opposed to a fixed
gain or a few predetermined selections.
•
Components with a return signaling path should be selected, especially in new designs.
This includes splitters and amplifiers. This return path is used by many devices to
communicate with the headend equipment of the client or the signal provider.
•
When detailing video splitters, always specify self-terminating ports. If they do not have
self-terminating ports, then specify the placement of 75 terminating caps for all unused
ports.
OSP Design Reference Manual, 4th edition
3-78
© 2007 BICSI®
Chapter 3: Cable Types
Subscriber Service Drops, continued
•
New systems should be designed for 900 to 1000 megahertz (MHz) signals (approximately 150 to160 channels). Most existing systems are 450 MHz (approximately 70 channels),
550 MHz (approximately 90 channels), or 700 MHz (approximately 110 channels) and are
migrating to 900 plus MHz systems.
Figure 3.20
Video link loss
Input signal
1000 MHz
-4.75 dB
Backbone
RG-11
375
-0.15 dB
-0.15 dB
TR
-8.25 dB
-15.9 dB
Loss Calculation
-0.15 dB connector
-4.75 dB 2-way splitter
-0.15 dB connector
-15.9 dB backbone cable (MC [CD] to TR)
-0.15 dB connector
-8.25 dB 4-way splitter
-0.15 dB connector
-14.6 dB distribution cable (TR to outlet)
-0.15 dB connector
-0.15 dB
-0.15 dB
Distribution
RG-6
225
-14.6 dB
Outlet
-0.15 dB
-44.25 dB Total Link Loss
db
MC (CD)
MHz
RG
TR
= decibel
= Main cross-connect (campus distributor)
= Megahertz
= Radio grade
= Telecommunications room
Determining Bandwidth Requirements
Bandwidth requirements have no bearing on determining coaxial cable size. The limiting factor
is the electronics and passive components.
Obtaining Loss Budgets for Electronics from the Customer
Loss budgets of the different types and sizes of cables depend on the gain and outputs of the
network electronics to be used. This was discussed earlier as a necessary means of
determining the size of coaxial cable along with distance, amplifier cascade, and cost.
© 2007 BICSI®
3-79
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Twinaxial Cabling
Introduction
Twinaxial cable is a configuration with two center conductors. Each individual conductor is
surrounded by a dielectric material, usually a hard or soft foam polymer, depending upon the
installation design specification and application. The dielectric material of both conductors is
wrapped with a continuous aluminum-polyester shield and tinned copper braid or other
shielding configurations (see Figure 3.21).
Figure 3.21
Twinaxial cable
Dielectric
Jacket
Foil shield
Braided shield
OSP Design Reference Manual, 4th edition
3-80
© 2007 BICSI®
Chapter 3: Cable Types
Hybrid Fiber Coaxial Cabling
Fiber coaxial telecommunications systems utilize both optical fiber cables and coaxial cabling
(see Figure 3.22). The signal, whether it represents data, video, or voice light, is digitally
generated. It is sent to a master signal converter within the base station where it is converted
to a light signal. It is then transmitted over a pair of singlemode or multimode optical fiber
cables from the master signal converter to a remotely located signal converter. The light signal
is then reconverted and transmitted to antennas via coaxial cabling.
The benefit of using both mediums is to transmit the signal by optical fiber over long distances
to multiple remote localized areas and then to broadcast it to several antennas via coaxial
cable. This system allows for greater channel capacities and smaller quantities and sizes of
cabling as well as for the use of centrally located switching equipment. Transmitting the signal
over coaxial cable only would not be a viable option because of the large cable diameter
required. Additionally, the signal would be severely attenuated over the long distance. Optical
fiber cable alone is not a good option either because of the increased numbers of fibers and
hardware needs. The combination of these media provides a much more cost-effective
system.
Figure 3.22
Optical fiber coaxial system
Remote
signal
converter
Antennas
(via couplers)
Tx
1
Rx
Communications
switch
equipment
Fiber
Master
signal
converter
Optical fiber
cable
Coaxial
cable
Tx
2
Rx
Tx
X
Rx
Rx = Receiver
Tx = Transmitter
© 2007 BICSI®
3-81
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
System Requirements
Space Allocation
The designer needs to consider the specific application of fiber coaxial systems and determine
the customer’s needs. The heart of the system is the switch or base station. These fiber
coaxial systems may be fed from concrete universal enclosures (CUEs), controlled
environment vaults (CEVs), or cabinets. There must be significant space to accommodate the
switching equipment along with the master signal converter unit within those spaces. To feed
the remote locations, routing must be determined via conduit, cable tray, or free air, if feasible.
Spare conduits or tray space must be identified or available space in the overhead or
underground must be determined if new conduits are to be installed.
For both optical fiber and coaxial cable, the bend radii and conduit fill code requirements must
be known and innerduct or sleeving should be used to facilitate the installation. Pulling
distances and tensions must be kept within specifications. The size and type of cable, along
with the conduit system, will determine the maximum pulling lengths. Although most
manufacturers offer flexible models, coaxial cable is typically rigid. Conduit should be
oversized to allow smooth installation without kinking or flattening the coaxial cable, which
may result in signal degradation and unwanted reflections. There also must be adequate space
in the various remote locations for installing remote signal converters, allowing space around
them for cooling and for splice enclosures.
Power
Power requirements must be determined at both remote and base locations. The designer
must determine if the remote units should be powered from the central base station location or
if each remote signal converter should receive power local to the units. Some benefits of
centralized power are adding a battery backup uninterruptible power supply (UPS) to the
system for more reliable operation and total control over remote power (i.e., no inadvertent
powering off of remote units). Benefits of powering each unit locally are decreased length of
power cabling back to the base station and elimination of power conduits.
Applications
Fiber coaxial cabling systems provide a variety of telecommunications applications. These
systems work particularly well for in-building solutions where there may be problems with
interference and long distances. Routing optical fiber cables from a central switch location
throughout campus environments and from building to building allows for expanded
communications. Positioning remote equipment and antennas from floor to floor within
dormitories provides easy access to the system.
OSP Design Reference Manual, 4th edition
3-82
© 2007 BICSI®
Chapter 3: Cable Types
Applications, continued
This type of system allows students to access the Internet for class information and to
communicate with professors and fellow classmates. It also allows administrators to distribute
informational video throughout the campus. Airports and hospitals are other prime candidates
for fiber coaxial cabling systems. The central switching equipment can be placed in a secure
area, and the fiber coaxial cable backbone can be used to feed the remote antennas. Several
airline terminals can be connected for internal security communication. Different floors of a
hospital can be linked to the communication system to better correspond in emergency
situations.
© 2007 BICSI®
3-83
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
Appendix: Rural Utilities Service (RUS) Type Cable
Rural Utilities Service (RUS) Type Cable
The RUS cable-coding plan differs from the Bell system type described previously in this
chapter. The following tables are for information purposes only. ICEA coding is the current
standard for cable coding and should be used in place of RUS coding.
Table 3.30 describes each of the codes used. This table shows an example of a standard
exchange solid conductor air core 19 AWG [0.91 mm (0.036 in)] CALPETH RUSacceptance 100-pair cable.
Table 3.30
RUS acceptance cable-coding plan
Cable
Core Type and
Design
Gauge
Conductor
Sheath
Code
Insulation
W
B
9
A
RUSPair Size
Designation Acceptance
R
0100
Table 3.31 lists and defines Western Electric Codes used in ordering a RUS type cable.
Table 3.31
Description of codes
Cable Code
K
Cable Design
Screened
cable
Core Code
A
Core Type
Filled foam
Conductor
Insulation
Gauge Code
9
2
4
6
AWG
19
22
24
26
Sheath Code
A
C
J
S
W
Type of Sheath
Coated
ALPETH
Gopherresistant
Self-support
Coated
alumninum
and coated
steel
Type Code
R
Cable Type
RUS-Acceptance
ALPETH
AWG
DEPIC
RUS
=
=
=
=
W
Standard
exchange cable
B
Air core solid
skin–DEPIC
5-mil copper
sheath
G
Filled solid
Aluminum polyethylene
American wire gauge
Dual-expanded plastic insulated conductor
Rural Utilities Service
OSP Design Reference Manual, 4th edition
3-84
© 2007 BICSI®
Chapter 3: Cable Types
References
American National Standards Institute. ANSI J-STD-607-A. Commercial Building
Grounding (Earthing) and Bonding Requirements for Telecommunications. Arlington, VA:
Telecommunications Industry Association, 2002.
American National Standards Institute/Telecommunications Industry Association/Electronic
Industries Alliance. ANSI/TIA/EIA-568-B.1. Commercial Building Telecommunications
Cabling Standard, Part 1: General Requirements. Arlington, VA: Telecommunications
Industry Association, 2001.
———. ANSI/TIA/EIA-568-B.1-3.Commercial Building Telecommunications Cabling
Standard, Part 1: General Requirements: Addendum 3–Supportable Distances and
Channel Attenuation for Optical Fiber Applications by Fiber Type. Arlington, VA:
Telecommunications Industry Association, 2003.
———. ANSI/TIA/EIA-568-B.3. Optical Fiber Cabling Components Standard. Arlington,
VA: Telecommunications Industry Association, 2000.
———. ANSI/TIA/EIA-568-B.3-1. Optical Fiber Cabling Component Standard–
Addendum 1–Additional Transmission Performance Specification for 50/125 μm Optical
Fiber Cables. Arlington, VA: Telecommunications Industry Association, 2002.
———. ANSI/TIA/EIA-569-B. Commercial Building Standard for Telecommunications
Pathways and Spaces. Arlington, VA: Telecommunications Industry Association, 2004.
———. ANSI/TIA/EIA-598-B. Optical Fiber Cable Color Code. Arlington, VA:
Telecommunications Industry Association, 2001.
———. ANSI/TIA/EIA-606-A. Administration Standard for Commercial Telecommunications Infrastructure. Arlington, VA: Telecommunications Industry Association, 2002.
———. ANSI/TIA/EIA-758-A. Customer-Owned Outside Plant Telecommunications
Infrastructure Standard. Arlington, VA: Telecommunications Industry Association, 2004.
BICSI®. Telecommunications Distribution Methods Manual, 11th edition. Tampa, FL:
BICSI, 2006.
Construction Specifications Institute. MasterFormat™. Divisions 1, 25, 27, and 28.
Alexandria, VA: Construction Specifications Institute, 2004.
Insulated Cable Engineers Association. ANSI/ICEA P-61-694. Coding Guide for Copper
Outside Plant and Riser Telecommunications Cables. Carrollton, GA: Insulated Cable
Engineers Association, 1999.
———. ANSI/ICEA S-84-608. Telecommunications Cable Filled, Polyolefin Insulated,
Copper Conductor. Carrollton, GA: Insulated Cable Engineers Association, 2002.
© 2007 BICSI®
3-85
OSP Design Reference Manual, 4th edition
Chapter 3: Cable Types
References, continued
———. ANSI/ICEA S-85-625. Telecommunications Cable Aircore, Polyolefin Insulated,
Copper Conductor Technical Requirements. Carrollton, GA: Insulated Cable Engineers
Association, 2002.
———. ANSI/ICEA S-86-634. Buried Telecommunications Wire Filled, Polyolefin
Insulated, Copper Conductor Technical Requirements. Carrollton, GA: Insulated Cable
Engineers Association, 2004.
———. ANSI/ICEA S-89-648. Standard for Aerial Service Wire Technical Requirements.
Carrollton, GA: Insulated Cable Engineers Association, 2000.
———. ANSI/ICEA S-91-674. Coaxial and Coaxial/Twisted Pair Composite Buried
Service Wires Technical Requirements. Carrollton, GA: Insulated Cable Engineers
Association, 2006.
———. ANSI/ICEA S-98-688. Broadband Twisted Pair Telecommunications Cable,
Aircore, Polyolefin Insulated, Copper Conductors Technical Requirements. Carrollton,
GA: Insulated Cable Engineers Association, 1997.
———. ANSI/ICEA S-99-689. Broadband Twisted Pair Telecommunications Cable,
Filled, Polyolefin Insulated, Copper Conductors Technical Requirements. Carrollton, GA:
Insulated Cable Engineers Association, 1997.
International Electrotechnical Commission. IEC 60794-5. Optical Fibre Cables—Part 5:
Sectional Specification—Microduct Cabling for Installation by Blowing. Geneva,
Switzerland: International Electrotechnical Commission, 2006.
National Fire Protection Association, Inc. NFPA 70. National Electrical Code®, 2005 edition.
Quincy, MA: National Fire Protection Association, 2005.
Telecommunications Industry Association. TIA-526-7. OFSTP-7— Measurement of Optical
Power Loss of Installed Single-Mode Fiber Cable Plant. Arlington, VA: Telecommunications Industry Association, 2002.
———. TIA-526-14-A. OFSTP-14—Optical Power Loss Measurements of Installed
Multimode Fiber Cable Plant. Arlington, VA: Telecommunications Industry Association,
1998.
U.S. Government Printing Office. Bulletin 1753F-204. REA Specification for Aerial Service
Wires (PE-7). Washington, DC: Rural Utilities Service, 1996.
———. Bulletin 1753F-205. REA Specification for Filled Telephone Cables (PE-39).
Washington, DC: Rural Utilities Service, 1993.
———. Bulletin 1753F-206. REA Specification for Filled Buried Wire (PE-86).
Washington, DC: Rural Utilities Service, 1993.
OSP Design Reference Manual, 4th edition
3-86
© 2007 BICSI®
Chapter 3: Cable Types
References, continued
———. Bulletin 1753F-208. REA Specification for Filled Telephone Cables with
Expanded Insulation (PE-89). Washington, DC: Rural Utilities Service, 1993.
———. Bulletin 1753F-601. REA Specification for Filled Fiber Optic Cables (PE-90).
Washington, DC: Rural Utilities Service, 1994.
Telcordia Technologies, Inc. GR-110-CORE. Thermoplastic Insulated Steam-Resistant
Metallic Cable. Piscataway, NJ: Telcordia Technologies, Inc., 1994, 2003.
———. GR-111-CORE. Thermoplastic Insulated Riser Cable. Piscataway, NJ: Telcordia
Technologies, Inc., 1995.
———. GR-421-CORE. Generic Requirements for Metallic Telecommunications Cables.
Piscataway, NJ: Telcordia Technologies, Inc., 1998.
———. GR-492-CORE. Generic Requirements for Metallic Telecommunications Wire.
Piscataway, NJ: Telcordia Technologies, Inc., 1994.
———. GR-1069-CORE. Generic Requirements for Non-Metallic Reinforced Aerial
Service Wire. Piscataway, NJ: Telcordia Technologies, Inc., 1998.
———. GR-1398-CORE. Coaxial Drop Cable. Piscataway, NJ: Telcordia Technologies,
Inc., 1996.
© 2007 BICSI®
3-87
OSP Design Reference Manual, 4th edition
Chapter 4
Cabling
Infrastructure
Chapter 4 discusses three fundamental cabling topologies—
star, ring, and bus—and the hybrid cabling topologies,
including star-wired ring, clustered star, hierarchical star,
and tree topologies.
Chapter 4: Cabling Infrastructure
Table of Contents
Introduction........................................................................................ 4-1
Outside Plant (OSP) ..................................................................................... 4-1
Topology ............................................................................................. 4-3
Star Topology ............................................................................................. 4-3
Hierarchical Star Topology ............................................................................. 4-5
Two-Level Hierarchical Star Topology .............................................................. 4-6
Physical Star/Logical Ring Topology ................................................................ 4-7
Physical Ring Topology .................................................................................. 4-8
Clustered Star Topology .............................................................................. 4-10
Optical Fiber Ring Topology .......................................................................... 4-11
Bus Topology ............................................................................................ 4-12
Tree and Branch Topology ........................................................................... 4-12
Figures
Figure 4.1
Star topology .................................................................................. 4-4
Figure 4.2
Hierarchical star topology ................................................................. 4-5
Figure 4.3
Physical star/logical ring topology ...................................................... 4-7
Figure 4.4
Buildings connected by a physical ring topology.................................... 4-8
Figure 4.5
Main backbone ring and redundant backbone star combined ................... 4-9
Figure 4.6
Clustered star topology with physical star/logical ring ......................... 4-10
Figure 4.7
Optical fiber ring topology (simplified) ............................................... 4-11
Figure 4.8
Bus topology ................................................................................. 4-12
Figure 4.9
Tree and branch topology ............................................................... 4-13
© 2007 BICSI®
4-i
OSP Design Reference Manual, 4th edition
Chapter 4: Cabling Infrastructure
OSP Design Reference Manual, 4th edition
4-ii
© 2007 BICSI®
Chapter 4: Cabling Infrastructure
Introduction
Outside Plant (OSP)
Outside plant (OSP) is the telecommunications cabling infrastructure designed for installations
exterior to buildings. These installations typically are routed into one or more entrance facilities
(EFs) in a building.
This OSP cabling infrastructure may be located on a customer’s property or between a
customer’s noncontiguous sites, which provides the capability to transport information
between buildings and other structures.
This chapter provides design requirements and guidelines for OSP telecommunications cabling
infrastructure, which includes telecommunications:
•
Pathways and spaces.
•
Cables.
•
Connecting hardware.
•
Grounding and bonding systems.
Campus backbone cabling is the segment of a network that presents the information transport
systems (ITS) distribution designer and end user with the most options and challenges,
particularly in major networks (e.g., universities, large industrial parks, military bases).
Campus backbone is also the network segment most affected by physical considerations
(e.g., duct availability, right-of-way [R/W], physical barriers).
There are three fundamental cabling topologies—star, ring, and bus. From these three, a
number of hybrid topologies have developed, including:
© 2007 BICSI®
•
Star-wired ring.
•
Clustered star.
•
Hierarchical star.
•
Tree.
•
Branch.
4-1
OSP Design Reference Manual, 4th edition
Chapter 4: Cabling Infrastructure
Outside Plant (OSP), continued
As protection against network downtime, many optical fiber cabling systems use redundancy.
Options for redundancy include:
•
Active equipment network devices that are coupled to optical fibers in the same cable as
the primary network system. If the primary network system fails, the redundant network
system will activate immediately. This protects against active device failure; however, it
does not help in the rare instance of a complete cable cut or some other form of
disconnection that results in an interruption of network transmission. Additional examples
of disconnection also may include:
– Removal of optical fiber patch cord assemblies or optical fiber equipment cords on
the user side of the system.
– Disconnection of optical fiber connectors from their associated optical fiber adapters on the cabling side of the system.
– One or more optical fiber strands that break or exhibit excessive loss on either the
user side or cabling side of the system.
NOTE: The user side of the cabling system is accessible to the user, and equipment
cords/cables are used to plug into the user side of the cabling system. The
cabling side of the system is accessible to cabling installers. Connections
made on the cabling side of a system are part of the permanent link model.
•
Physical diverse routing, which provides the most protection. A redundant optical fiber
cable is placed in a second diverse route to activate immediately if cable is damaged.
Consider using physical diversity in cases where minimum downtime for the infrastructure
is a requirement. Physically diverse cabling is more costly than coupled active equipment
devices.
OSP Design Reference Manual, 4th edition
4-2
© 2007 BICSI®
Chapter 4: Cabling Infrastructure
Topology
Star Topology
A star topology generally is deployed for OSP cabling. Star configurations allow all buildings to
be cabled directly from the main cross-connect (MC [campus distributor (CD)]). These
configurations centralize the physical management of the backbone network.
A star topology directly links all buildings requiring connection to the MC (CD). See
Figure 4.1. These direct links between the MC (CD) and the intermediate cross-connect
(IC [building distributor (BD)]) sometimes are referred to as home runs. The cross-connect in
each building then becomes the IC (BD), linking the telecommunications rooms (TRs) from
their associated horizontal cross-connects (HC [floor distributors (FDs)]) in each building to
the MC (CD).
By centralizing the physical management of the backbone cabling at the MC (CD), the owner
has the opportunity to connect the network to a remote location or campus. For example, this
connection can be made via microwave, satellite, or leased lines.
© 2007 BICSI®
4-3
OSP Design Reference Manual, 4th edition
Chapter 4: Cabling Infrastructure
Star Topology, continued
The MC (CD) should be close to (if not colocated with) the primary equipment room (ER).
Ideally, the MC (CD) will:
•
Be at the center of the buildings being served.
•
Provide adequate space for cross-connect hardware and equipment.
Some of the advantages of using a star topology for the campus backbone cabling are that it:
•
Provides centralized facilities administration.
•
Allows testing and reconfiguration of the system’s topology and applications from the
MC (CD).
•
Provides increased flexibility.
Figure 4.1
Star topology
MC
(CD)
Building A
MC (CD) = Main cross-connect (campus distributor)
OSP Design Reference Manual, 4th edition
4-4
© 2007 BICSI®
Chapter 4: Cabling Infrastructure
Hierarchical Star Topology
If the distance from the switch to the last workstation exceeds the transmission limit, the
designer should consider using a hierarchical star configuration. In this configuration, the first
level backbone either cross-connects or interconnects to the second level backbone via active
network equipment.
Each cabling segment may connect to a centralized location that supports the area as a star
topology where Building A is star cabled to Building F, and then Building F is star cabled to
Buildings G, H, and J (see Figure 4.2). Node locations can be connected to other topologies to
support technologies and equipment used for wide area applications such as:
•
Wireless.
•
Synchronous optical network (SONET).
•
Integrated services digital network (ISDN).
•
x Digital subscriber line (xDSL).
•
Asynchronous transfer mode (ATM).
•
Hybrid fiber/coaxial (HFC).
Figure 4.2
Hierarchical star topology
Building C
Building B
Building H
Building E
Building A
MC (CD)
Building F
IC (BD)
Building G
Building D
Building J
Level 2
IC (BD) = Intermediate cross-connect (building distributor)
MC (CD) = Main cross-connect (campus distributor)
© 2007 BICSI®
4-5
OSP Design Reference Manual, 4th edition
Chapter 4: Cabling Infrastructure
Two-Level Hierarchical Star Topology
A two-level hierarchical star design provides an interbuilding backbone that uses selected ICs
(BDs) to serve a number of buildings, rather than linking all the buildings directly to the MC
(CD). The ICs (BDs) are then linked to the MC (CD).
Consider using a two-level hierarchical star when available pathways do not allow for all
cables to be routed to an MC (CD) or when geographical or user grouping requirements make
it desirable to segment the network physically.
In large networks, this allows electronics (e.g., switches) to be used more effectively to utilize
bandwidth and distance capabilities of the cabling or to segment the network physically.
Many designers consider the two-level hierarchical star beneficial, especially if the number of
interbuilding ICs (BDs) is held to a minimum.
When the two-level hierarchical star is used for an interbuilding backbone, a physical star
should be implemented in all segments. This will ensure that flexibility, versatility, and
manageability are maintained.
OSP Design Reference Manual, 4th edition
4-6
© 2007 BICSI®
Chapter 4: Cabling Infrastructure
Physical Wired Star/Logical Ring Topology
A physical star/logical ring topology indicates the OSP cable is physically constructed in a star
configuration but the signaling will be routed in a logical ring topology. This type of configuration should be used when the designer determines that a physical ring route is not possible or
an existing cable will be used in a segment of the total project (see Figure 4.3).
Figure 4.3
Physical star/logical ring topology
Node B
Node C
IC (BD)
IC (BD)
MC (CD)
IC (BD)
Node D
IC (BD)
Node A
IC (BD) = Intermediate cross-connect (building distributor)
MC (CD) = Main cross-connect (campus distributor)
This topology allows for concentration of backup systems, maintenance, and performance
monitoring personnel to be located at the MC (CD). This creates economies of scale in
network operational costs and upgrades by concentrating a majority of the network hardware
at a central location. The downside, however, is a single point of failure.
© 2007 BICSI®
4-7
OSP Design Reference Manual, 4th edition
Chapter 4: Cabling Infrastructure
Physical Ring Topology
The designer may consider using a physical ring (see Figure 4.4) to link the interbuilding ICs
(BDs) and MC (CD) when:
•
The existing pathways (e.g., conduit) support it.
•
The primary purpose of the network is optical fiber distributed data interface (FDDI),
SONET, or token ring.
•
There is a redundant cable path.
Figure 4.4
Buildings connected by a physical ring topology
IC (BD)
IC (BD)
See note
MC
(CD)
IC (BD)
IC (BD)
IC (BD)
IC (BD)
IC (BD) = Intermediate cross-connect (building distributor)
MC (CD) = Main cross-connect (campus distributor)
The typical optical fiber cores/strands design for a cabling system that provides physical ring
routing would dedicate some of the optical fiber core strands to a ring and some to a star by
splicing through the ICs (BDs) back to the MC (CD).
NOTE:
This generally is not recommended without direct connection to an MC (CD).
OSP Design Reference Manual, 4th edition
4-8
© 2007 BICSI®
Chapter 4: Cabling Infrastructure
Physical Ring Topology, continued
Figure 4.5 gives the end user the best cabling system configuration. However, the designer
must have a significantly detailed definition of present and future telecommunications
requirements before designing this kind of arrangement.
Figure 4.5
Main backbone ring and redundant backbone star combined
MC (CD)
IC ( B D ) 1
IC ( B D ) 3
IC(BD) 2
48-Optical fiber cable
(6 ring optical fibers and
42 star optical fibers)
= 6 Ring fibers
= 12 Star fibers
= Optical fiber patch panel
= Optical fiber splice center
= Splices
IC (BD) = Intermediate cross-connect (building distributor)
MC (CD) = Main cross-connect (campus distributor)
© 2007 BICSI®
4-9
OSP Design Reference Manual, 4th edition
Chapter 4: Cabling Infrastructure
Clustered Star Topology
A clustered star with or without a physical star/logical ring indicates that from the MC (CD)
to the node sites the topology can be either a star or a ring topology (see Figure 4.6). This
determination is at the designer’s discretion and is based upon the electronics, designer’s
survivability plans, and transmission budget selected at the MC (CD) and each node site.
Figure 4.6
Clustered star topology with physical star/logical ring
Bldg 4
Bldg 3
Bldg 5
Node site B
Bldg 2
Bldg 6
Bldg 7
Node site A
Bldg 8
MC (CD)
Node site C
Bldg 1
MC (CD) = Main cross-connect (campus distributor)
At the node site, the buildings are served via a physical star topology. The node sites have the
ability to be either a star or ring configuration. This topology allows a designer to provide for
fault-tolerant redundant routing at the node locations. At the same time, the designer can
reduce the design costs for electronics and OSP cable from the node sites to the buildings via
a ring or a star network topology. This configuration also takes advantage of the concentration
of electronic equipment in a common location for network management operations and
efficiency.
OSP Design Reference Manual, 4th edition
4-10
© 2007 BICSI®
Chapter 4: Cabling Infrastructure
Optical Fiber Ring Topology
The optical fiber ring topology depicted in Figure 4.7 is a simplified view of a typical ring
application. Optical fiber ring strategies can become very sophisticated and complex in their
routing schemes and primary and protection switching capabilities. Most simple rings are
designed to provide a primary path and a secondary path in case there is either an electronic
failure at a node site or a service interruption related to the OSP cable.
In an optical fiber ring topology, separate and independent physical pathways are recommended for primary and secondary rings.
Figure 4.7
Optical fiber ring topology (simplified)
Node A
Node D
Node B
Ring signaling
direction
Node C
Optical fiber ring topologies are increasingly becoming the normal design architecture for OSP
operations because they can support high bandwidth transport applications. Ring topologies
provide the following benefits:
© 2007 BICSI®
•
Fault-tolerant redundant routing
•
Greater reliability and significantly less cabling service downtime
•
Flexible architecture
4-11
OSP Design Reference Manual, 4th edition
Chapter 4: Cabling Infrastructure
Bus Topology
A bus topology is a linear configuration of cabling that has limited application if the designer is
looking for fault-tolerant redundancy (see Figure 4.8). A bus topology is adequate if the route
is secure (protected from breaks), redundancy is not required, and the system traffic is not of
a significantly critical nature to require alternate routing. All points along the cable route are in
communication with each other. If the route should suffer a break, all network communications would be lost.
Figure 4.8
Bus topology
Building B
IC (BD)
MC (CD)
IC (BD)
Building C
Building A
ER
Building D
ER = Equipment room
IC (BD) = Intermediate cross-connect (building distributor)
MC (CD) = Main cross-connect (campus distributor)
Tree and Branch Topology
Tree and branch topology typically refers to the configuration of the cabling from a node site,
or directly from the MC (CD). This terminology is used in the planning for coaxial cables for
community antenna television (CATV) operations. The terminology describes the main trunk
of a tree with subsequent branches extending from this trunk line. It may extend in multiple
directions. The trunk is normally referred to in the telephony industry as feeder cable and the
branch is distribution cable (see Figure 4.9). In the CATV industry, the terminology is reversed
and the trunk is the main line from the headend to the branch, called the feeder cable. The
parameters for the design of this type of network are dependent upon the loss characteristics
of the coaxial cabling and the geographic area to be served.
OSP Design Reference Manual, 4th edition
4-12
© 2007 BICSI®
Chapter 4: Cabling Infrastructure
Tree and Branch Topology, continued
Figure 4.9
Tree and branch topology
Bldg
A
Typical
Bldg
B
MC
(CD)
Bldg
D
Bldg
C
Bldg
E
Bldg
F
Bldg
G
MC (CD) = Main cross-connect (campus distributor)
NOTE:
© 2007 BICSI®
Locations such as this in a cabling system can take on many different configura
tions depending on the type of cabling system. For cabling in general, this point
could be a handhole (HH) with one cable from the MC (CD) through the HH to
Building A, and one cable from the MC (CD) through the HH to Building B. If this
is a balanced twisted-pair cable, this could be a 100-pair cable from the MC (CD)
to a maintenance hole (MH) with a splice. The splice could have the first binder
group run to Building B, the second binder group run to Building A, and the third and
fourth binder groups as spares for future requirements. If this were a CATV cable,
this could be a feeder or trunk cable to an HH and a tap, sending one cable to
Building A and one cable to Building B. This also could be an optical fiber network
with a cable from the MC (CD) to an MH and spliced into an optical fiber cable to
Building A and one to Building B.
4-13
OSP Design Reference Manual, 4th edition
Chapter 5
Pathways and
Spaces
Chapter 5 identifies the types of pathways and spaces
subject to outside plant (OSP) design—underground
pathways, direct-buried pathways, aerial pathways,
maintenance holes (MHs), handholes (HHs), controlled
environment vaults (CEVs), and concrete universal
enclosures (CUEs). It discusses the details of construction,
cabling placement, and supporting infrastructure.
Chapter 5: Pathways and Spaces
Table of Contents
Route Design ...................................................................................... 5-1
Introduction ................................................................................................ 5-1
Preliminary Investigations and Surveys ............................................................ 5-1
Site Survey ................................................................................................. 5-2
Route Construction ................................................................................. 5-2
Alternate Route Considerations ...................................................................... 5-4
Flagging, Painting, and Marking Utilities ........................................................... 5-5
Test Holes (Potholes) ................................................................................... 5-5
Documentation ............................................................................................ 5-6
Right-of-Way (R/W) ..................................................................................... 5-6
Joint Use Occupancy .................................................................................... 5-6
Pathways ........................................................................................... 5-7
Introduction ................................................................................................ 5-7
Underground ............................................................................................... 5-7
Direct-Buried ............................................................................................... 5-7
Aerial ......................................................................................................... 5-8
SECTION 1: UNDERGROUND PATHWAYS
Underground Pathways ...................................................................... 5-9
Introduction ................................................................................................ 5-9
Conditions Requiring Conduit Construction ...................................................... 5-13
Economics ................................................................................................ 5-13
Conduit System Planning ............................................................................. 5-14
Finished Conduit System Design ................................................................... 5-15
Conduit System Requirements ...................................................................... 5-15
Future Conduit System Requirements ............................................................ 5-17
Planning Lateral Ducts ................................................................................ 5-17
Planning Subsidiary Ducts ............................................................................ 5-18
Section Length/Diameter Considerations ........................................................ 5-19
Maintenance Hole (MH) Location and Quantity ............................................... 5-20
Clearances ................................................................................................ 5-21
© 2007 BICSI®
5-i
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Conduit Depth ........................................................................................... 5-21
Live or Dynamic Loads ................................................................................ 5-22
Dead or Earth Loads ................................................................................... 5-23
Tensile Stresses ........................................................................................ 5-23
Drain Slope ............................................................................................... 5-24
Conduit Formations .................................................................................... 5-24
Advantages of Constructing Formations Using Individual Conduit .................. 5-25
Advantages of Multiple-Bore Conduit ............................................................. 5-27
Types of Conduit ....................................................................................... 5-27
Selecting a Type of Conduit ......................................................................... 5-28
Galvanized Rigid Steel Conduit ................................................................. 5-29
Conduit Construction .................................................................................. 5-30
Using Innerduct .................................................................................... 5-31
Conduit Casings .................................................................................... 5-33
Wall Thickness of Casing Pipe .................................................................. 5-34
Calculating Conduit Pulling Tensions .............................................................. 5-35
Coefficient of Friction (f) ....................................................................... 5-36
Calculating Pulling Tension for Straight Horizontal Conduit ............................ 5-37
Calculating Pulling Tension for Inclined Straight Segment of Conduit .............. 5-38
Calculating Pulling Tension for Uniformly Curved Segment of Conduit ............. 5-39
Cumulative Tension Worksheet ................................................................ 5-42
Designing Curved Conduit Sections ............................................................... 5-48
Air-Assisted Cable Installation ...................................................................... 5-48
Microduct ................................................................................................. 5-50
Calculating Volume of Backfill ....................................................................... 5-51
Trench Work .............................................................................................. 5-53
Subsurface Space ................................................................................. 5-57
Conduit Design for Bridge Crossing ................................................................ 5-57
Under Bridge Hanger/Conduit Method ....................................................... 5-58
Tunnels ............................................................................................. 5-67
Introduction .............................................................................................. 5-67
Utility Tunnels ........................................................................................... 5-67
Pedestrian Tunnels ..................................................................................... 5-69
Vehicular Tunnels ....................................................................................... 5-69
Motivating Design Factors ........................................................................... 5-70
OSP Design Reference Manual, 4th edition
5-ii
© 2007 BICSI®
Chapter 5: Pathways and Spaces
Application Areas ....................................................................................... 5-70
Advantages .............................................................................................. 5-70
Disadvantages ........................................................................................... 5-70
Utility Requirements ................................................................................... 5-71
Hazards .................................................................................................... 5-71
Ventilation ................................................................................................ 5-72
Fire Detection ........................................................................................... 5-72
Support Structures .................................................................................... 5-72
SECTION 2: DIRECT-BURIED PATHWAYS
Direct-Buried Pathways .................................................................... 5-73
Introduction .............................................................................................. 5-73
Route Selection ......................................................................................... 5-73
Plow Route Selection .................................................................................. 5-75
Burial Depth .............................................................................................. 5-75
Placing Direct-Buried Cable ............................................................... 5-77
Trenching ................................................................................................. 5-77
Plowing .................................................................................................... 5-78
Vibratory Plow ...................................................................................... 5-79
Rip Plow .............................................................................................. 5-80
Rock Saw ............................................................................................ 5-80
Clearances from Existing Utilities ............................................................. 5-81
Boring ...................................................................................................... 5-81
Auger Bore System ................................................................................ 5-81
Horizontal Directional Drilling (HDD) .......................................................... 5-83
Missile Bore System ............................................................................... 5-84
Casing Type ......................................................................................... 5-84
Cable Markers ....................................................................................... 5-84
SECTION 3: AERIAL PATHWAYS
Aerial Pathways ............................................................................... 5-85
Introduction .............................................................................................. 5-85
Route Selection ......................................................................................... 5-85
Designing New Aerial Support Structures ....................................................... 5-86
Grades of Pole and Pole Line Construction ................................................. 5-86
Reuse of Existing Poles and Pole Lines ...................................................... 5-86
© 2007 BICSI®
5-iii
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Types of Loading ....................................................................................... 5-87
Storm Load Requirements ............................................................................ 5-88
Combined Ice and Wind Loading .............................................................. 5-89
Light Loading ........................................................................................ 5-89
Medium Loading .................................................................................... 5-89
Heavy Loading ...................................................................................... 5-89
Extreme Wind Loading ............................................................................ 5-90
Required Pole Strength .......................................................................... 5-91
Moment Strength .................................................................................. 5-91
Method of Summing Loads ...................................................................... 5-91
Pole Classification ...................................................................................... 5-92
Numerical Classification of Poles ................................................................... 5-93
Pole Depth Belowground .............................................................................. 5-99
Depth Requirement ................................................................................... 5-100
Compaction ............................................................................................. 5-102
Transverse Load on a Pole from Aerial Line ................................................... 5-102
Storm-Loading Districts ........................................................................ 5-102
Load Table ......................................................................................... 5-103
Moment ............................................................................................. 5-104
Transverse Load from Wind Pressure on Pole ........................................... 5-104
Assumed Load .................................................................................... 5-104
Loads Imposed by Service Drop Wires ......................................................... 5-105
Unbalanced Service Drop Wires ............................................................. 5-105
Balanced Drop Wires ............................................................................ 5-105
Loads Imposed by Pole Attachments ........................................................... 5-105
Transverse Load Calculation ...................................................................... 5-106
Conditions ......................................................................................... 5-106
Calculation ......................................................................................... 5-106
Estimation ......................................................................................... 5-107
Required Resistant Moment ................................................................... 5-107
Selection ............................................................................................... 5-107
Selection of Pole Class ......................................................................... 5-107
Vertical Load ........................................................................................... 5-108
Bending Moments (Longitudinal Loads) ........................................................ 5-109
Calculation of Pole Height .......................................................................... 5-109
Attachment Space .............................................................................. 5-109
Pole Spacing and Span Lengths .................................................................. 5-110
Total Weight and Maximum Span Lengths of the Cable ................................... 5-112
OSP Design Reference Manual, 4th edition
5-iv
© 2007 BICSI®
Chapter 5: Pathways and Spaces
Special Situation Designs .......................................................................... 5-117
Optical Fiber Cable Considerations ......................................................... 5-117
Slack Span Design ............................................................................... 5-118
Pole to Building Design ......................................................................... 5-119
Flying Cross Construction ..................................................................... 5-120
Clearances .............................................................................................. 5-120
Attachment Clearances ........................................................................ 5-121
Midspan Clearances ............................................................................. 5-122
Vertical Clearances .............................................................................. 5-123
Facility Clearances (Government) .......................................................... 5-126
Radial Clearances ................................................................................ 5-126
Support Strands ...................................................................................... 5-127
Support Strand Size ............................................................................ 5-127
Anchor and Guys ..................................................................................... 5-128
Anchor and Guys Support Strands ......................................................... 5-128
Anchor and Guy Configuration ............................................................... 5-128
Common Anchor and Guy Configurations ................................................. 5-128
Guy Attachment Hardware ................................................................... 5-130
Storm Guying ..................................................................................... 5-131
Lead-to-Height Ratio ........................................................................... 5-132
Measuring the Corner Pull ..................................................................... 5-133
Calculating Guy Strength ...................................................................... 5-136
Guy Size ............................................................................................ 5-137
Anchors ............................................................................................. 5-140
Soil Classifications ............................................................................... 5-141
Guy Rod Size ...................................................................................... 5-143
Guy Rod Ends ..................................................................................... 5-143
Selection of Anchors ........................................................................... 5-145
Location and Installation of Anchors ...................................................... 5-148
Designing Additions to Existing Aerial Support Structures ................................ 5-149
Pole Line Adequacy ............................................................................. 5-149
Pole Line Construction Classification ....................................................... 5-149
System Plans ..................................................................................... 5-151
Joint-Use Agreements .......................................................................... 5-151
Makeready Work ................................................................................. 5-151
Design Transition Structures ...................................................................... 5-151
© 2007 BICSI®
5-v
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
SECTION 4: AERIAL CONSTRUCTION PRACTICES
Placement ...................................................................................... 5-157
Depth of Pole Setting ............................................................................... 5-157
General ............................................................................................. 5-157
Firm Soil or Solid Rock .......................................................................... 5-158
Soil and Rock ..................................................................................... 5-159
Frozen Soil ......................................................................................... 5-161
Swampy Soil ...................................................................................... 5-164
Sloping Ground ................................................................................... 5-164
River or Stream Bank ........................................................................... 5-166
Unguyed Angles .................................................................................. 5-167
Restrictions of Pole Height ......................................................................... 5-167
Selection of Base Pole .............................................................................. 5-167
Diameter and Depth of Holes ...................................................................... 5-167
Diameter of Pole Holes ......................................................................... 5-167
Depth of Pole Holes ............................................................................. 5-167
Average Depth in Firm Ground or Solid Rock at Ground Level ...................... 5-167
Solid Rock below Ground Level .............................................................. 5-168
Methods of Digging Pole Holes .................................................................... 5-168
Digging Holes with Hand Tools ............................................................... 5-168
Boring Holes with Earth Boring Machine ................................................... 5-171
Water Jet Method of Setting Poles ......................................................... 5-171
Blasting Pole Holes .............................................................................. 5-172
Methods of Raising and Setting Poles ............................................. 5-173
Line Truck Method ................................................................................... 5-173
A-Frame Line Truck ............................................................................. 5-173
Line Truck Equipped with Hydraulic/Mechanical Derrick .............................. 5-176
Hand and Pike Pole Method ................................................................... 5-177
Backfilling and Tamping ........................................................................ 5-179
Raking Poles ............................................................................................ 5-179
Dead End and Corner Pole Raking ........................................................... 5-179
Footings for Poles .................................................................................... 5-181
Plank Footings .................................................................................... 5-181
Catenary Span Poles ........................................................................... 5-182
OSP Design Reference Manual, 4th edition
5-vi
© 2007 BICSI®
Chapter 5: Pathways and Spaces
Plank Bracing and Platform Supports ...................................................... 5-183
Platform Supports with Side Guys .......................................................... 5-185
Platform Supports at H Fixtures ............................................................. 5-186
Ground Braces ......................................................................................... 5-187
Log Braces ......................................................................................... 5-187
Plank Ground Braces ............................................................................ 5-189
Push Braces ............................................................................................ 5-189
Length of Push Braces ......................................................................... 5-189
Determining Individual Push Brace Length ................................................ 5-190
Position of Push Braces ........................................................................ 5-192
Installation of Push Braces ........................................................................ 5-192
Push Brace at Single Poles ................................................................... 5-192
Double Push Braces ............................................................................. 5-195
Push-Pull Braces ................................................................................. 5-196
SECTION 5: SPACES
Spaces ............................................................................................ 5-199
Introduction ............................................................................................ 5-199
Confined Spaces ...................................................................................... 5-199
Maintenance Holes (MHs) .......................................................................... 5-200
Choosing Precast or Site-Poured Maintenance Hole (MH) ................................ 5-206
Maintenance Hole (MH) Size Extensions ....................................................... 5-206
Selecting Maintenance Hole (MH) by Duct Entrance ...................................... 5-207
Maintenance Hole (MH) Types .................................................................... 5-210
Cable Racking Provisions ........................................................................... 5-214
Administration ......................................................................................... 5-215
Sealing Ducts .......................................................................................... 5-215
Openings, Covers, and Frames ................................................................... 5-215
Maintenance Hole (MH) Extension Rings ....................................................... 5-217
Handholes (HHs) ............................................................................ 5-218
Location ................................................................................................. 5-220
Pedestals, Cabinets, and Vaults ...................................................... 5-221
Introduction ............................................................................................ 5-221
Ground-Level Pedestals and Cabinet Criteria ................................................. 5-222
© 2007 BICSI®
5-vii
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Cabinets ................................................................................................. 5-223
Pole/Wall Mounted Cabinets .................................................................. 5-223
Environmentally Controlled Cabinets ....................................................... 5-223
Controlled Environment Vault (CEV) ............................................... 5-225
Concrete Universal Enclosure (CUE) ............................................... 5-226
Marinas ........................................................................................... 5-227
Service at Marinas ................................................................................... 5-227
Terms and Definitions ............................................................................... 5-227
Docks with Floating Sections ..................................................................... 5-227
Designating Specific Docks for Service ........................................................ 5-228
Precabling Boat Slips ................................................................................ 5-228
Using Mechanical Protection ...................................................................... 5-229
Protecting Cable, Conductors, and Terminals ................................................ 5-229
Choosing Conduit Size and Type ................................................................. 5-229
Bonding and Grounding (Earthing) ............................................................... 5-230
System Separation ................................................................................... 5-230
Condominium Slips .................................................................................... 5-232
References ..................................................................................... 5-234
OSP Design Reference Manual, 4th edition
5-viii
© 2007 BICSI®
Chapter 5: Pathways and Spaces
Figures
Figure 5.1
Lateral and subsidiary conduits ................................................... 5-16
Figure 5.2
Live or dynamic load dispersal ..................................................... 5-22
Figure 5.3
Dead or earth load dispersal ....................................................... 5-23
Figure 5.4
Conduit casings under railroads ................................................... 5-33
Figure 5.5
Conduit casings under highway ................................................... 5-34
Figure 5.6
Forces acting on cable pulled through straight conduit ................... 5-37
Figure 5.7
Inclined straight conduit ............................................................ 5-39
Figure 5.8
Simple bend ............................................................................. 5-40
Figure 5.9
Microduct ................................................................................ 5-50
Figure 5.10
Typical concrete-encased conduit structure ................................. 5-51
Figure 5.11
Typical compacted fill conduit structure ....................................... 5-52
Figure 5.12
Typical trench shield ................................................................. 5-53
Figure 5.13
Typical trench with shoring in unstable ground .............................. 5-54
Figure 5.14
Typical trench with shoring in stable ground .................................. 5-55
Figure 5.15
Bell end conduit slip sleeve ......................................................... 5-57
Figure 5.16
Expansion joints ....................................................................... 5-58
Figure 5.17
Angle bracing ........................................................................... 5-59
Figure 5.18
Longitudinal bracing and load forces ............................................ 5-60
Figure 5.19
Anchor and plug ....................................................................... 5-61
Figure 5.20
Back-to-back expansion joint units .............................................. 5-61
Figure 5.21
Back-to back expansion joint ...................................................... 5-62
Figure 5.22
In-line single-expansion joint over 30.5 m (100 ft) ......................... 5-62
Figure 5.23
Expansion joint under 30.5 m (100 ft) .......................................... 5-63
Figure 5.24
Single expansion joint ................................................................ 5-63
Figure 5.25
Angle bracing into stranded area ................................................. 5-64
Figure 5.26
Conduit installed in sidewalk portion of bridge ................................ 5-65
Figure 5.27
Conduit installed by hanging under sidewalk portion of bridge .......... 5-65
Figure 5.28
Conduit run attached to side of bridge with steel brackets .............. 5-66
Figure 5.29
Conduit runs attached to steel I-beams ....................................... 5-66
Figure 5.30
Typical shallow tunnel section .................................................... 5-68
Figure 5.31
Protection of direct-buried cable ................................................. 5-74
Figure 5.32
Walk behind trencher ................................................................. 5-77
Figure 5.33
Tractor-drawn trencher ............................................................. 5-78
Figure 5.34
Trencher/vibratory plow ............................................................. 5-79
© 2007 BICSI®
5-ix
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Figure 5.35
Vibratory plow .......................................................................... 5-79
Figure 5.36
Rip plow .................................................................................. 5-80
Figure 5.37
Rock saw ................................................................................ 5-80
Figure 5.38
Auger bore .............................................................................. 5-82
Figure 5.39
Horizontal directional drilling machine ........................................... 5-83
Figure 5.40
Wind and ice loadings ................................................................ 5-88
Figure 5.41
Example of keying a pole .......................................................... 5-101
Figure 5.42
Pole placement utilizing terrain feature ....................................... 5-110
Figure 5.43
Slack span ............................................................................. 5-118
Figure 5.44
Building attachment methods .................................................... 5-119
Figure 5.45
Flying cross ........................................................................... 5-120
Figure 5.46
Midspan clearances ................................................................. 5-122
Figure 5.47
Vertical clearances over obstacles ............................................ 5-123
Figure 5.48
Vertical clearances between utilities .......................................... 5-124
Figure 5.49
Clearance distances ................................................................ 5-126
Figure 5.50
Push brace ............................................................................ 5-129
Figure 5.51
Guying configurations .............................................................. 5-130
Figure 5.52
Storm Guying ......................................................................... 5-131
Figure 5.53
Definition of lead and height ..................................................... 5-132
Figure 5.54
Calculating pull with pull finder .................................................. 5-133
Figure 5.55
Calculating pull with tape measure ............................................ 5-134
Figure 5.56
Guy rule ................................................................................ 5-138
Figure 5.57
Using guy strand selection chart example ................................... 5-139
Figure 5.58
Types of common anchors ........................................................ 5-140
Figure 5.59
Guy rod ends ......................................................................... 5-144
Figure 5.60
Aerial to underground transition ................................................ 5-152
Figure 5.61
Aerial to direct-buried transition ................................................ 5-152
Figure 5.62
Underground to direct-buried transition ...................................... 5-153
Figure 5.63
Underground to building transition ............................................. 5-153
Figure 5.64
Aerial to building transition ....................................................... 5-154
Figure 5.65
Direct-buried to building transition ............................................. 5-155
Figure 5.66
Typical settings of poles in permafrost ....................................... 5-162
Figure 5.67
Effect on pole when active layer above permafrost is refrozen ....... 5-163
Figure 5.68
Setting pole in sloping ground ................................................... 5-165
Figure 5.69
Typical pole crib ..................................................................... 5-166
Figure 5.70
Digging pole hole with hand tools .............................................. 5-169
Figure 5.71
Digging pole hole with a water jet ............................................. 5-172
OSP Design Reference Manual, 4th edition
5-x
© 2007 BICSI®
Chapter 5: Pathways and Spaces
Figure 5.72
Setting pole using A-frame line truck ......................................... 5-174
Figure 5.73
Sighting pole to ensure it is level and plumb ................................ 5-175
Figure 5.74
Raising pole using manpower, pole pikes,
and a deadman pole support .................................................... 5-178
Figure 5.75
Raking pole prior to tamping ..................................................... 5-180
Figure 5.76
Plank footing for pole .............................................................. 5-181
Figure 5.77
Plank footing and catenary design ............................................. 5-182
Figure 5.78
Plank and log footing and catenary design .................................. 5-183
Figure 5.79
Platform support ..................................................................... 5-184
Figure 5.80
Side guys and platform support ................................................. 5-185
Figure 5.81
Platform support at H fixture .................................................... 5-186
Figure 5.82
Log ground brace ................................................................... 5-188
Figure 5.83
Measuring for push brace ......................................................... 5-191
Figure 5.84
Push brace on single pole ......................................................... 5-193
Figure 5.85
Push brace on H fixture ........................................................... 5-194
Figure 5.86
Double push brace .................................................................. 5-195
Figure 5.87
Push-pull brace ...................................................................... 5-197
Figure 5.88
Typical maintenance hole (cutaway side view) ............................ 5-201
Figure 5.89
Maintenance hole diagram ........................................................ 5-202
Figure 5.90
Maintenance hole frame, cover, and collar .................................. 5-203
Figure 5.91
Center conduit tray ................................................................ 5-204
Figure 5.92
Splayed conduit entry ............................................................. 5-204
Figure 5.93
Basic A precast maintenance hole ............................................. 5-205
Figure 5.94
Type A maintenance hole with center conduit window (plan view) .. 5-210
Figure 5.95
Type A maintenance hole with splayed window (plan view) ........... 5-210
Figure 5.96
Type J maintenance hole with center conduit window (plan view) .. 5-211
Figure 5.97
Type J maintenance hole with splayed conduit windows (plan view) 5-211
Figure 5.98
Type L maintenance hole with center conduit window (plan view) .. 5-212
Figure 5.99
Type L maintenance hole with splayed conduit window (plan view) . 5-212
Figure 5.100
Type T maintenance hole with center conduit window (plan view) .. 5-213
Figure 5.101
Type T maintenance hole with splayed conduit window (plan view) 5-213
Figure 5.102
Typical cable maintenance hole ................................................. 5-214
Figure 5.103
Typical handhole .................................................................... 5-219
Figure 5.104
Pedestals and cabinets ............................................................ 5-224
Figure 5.105
Modular floating dock layout ..................................................... 5-231
Figure 5.106
Sample marina layout .............................................................. 5-233
© 2007 BICSI®
5-xi
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Tables
Table 5.1
Uniform color code for utility flagging, painting, or marking ................ 5-5
Table 5.2
Domestic and international one-call locate company
telephone numbers ..................................................................... 5-9
Table 5.3
Clearances .............................................................................. 5-21
Table 5.4
Conduit formations .................................................................... 5-25
Table 5.5
Straight lengths of individual conduit ........................................... 5-26
Table 5.6
Rigid bends for 100 mm (4 trade size) individual conduit .................. 5-26
Table 5.7
Galvanized rigid steel conduit sizes .............................................. 5-30
Table 5.8
Coefficient of friction ................................................................ 5-36
Table 5.9
Cable pulling tension ................................................................. 5-41
Table 5.10
Cubic yards of concrete per 30.5 m (100 ft) of trench .................... 5-51
Table 5.11
Cubic yards of compacted fill per 30.5 m (100 ft) of trench ............. 5-52
Table 5.12
Minimum trench shoring requirements ........................................... 5-56
Table 5.13
Ice, wind, and temperature ........................................................ 5-90
Table 5.14
Pole class and transverse breaking strength .................................. 5-92
Table 5.15
Pole resistance moments ........................................................... 5-94
Table 5.16
Rated fiber strength for pole species ........................................... 5-94
Table 5.17
Resistance moments for various sizes of poles ............................... 5-95
Table 5.18
Pole setting depth required for various heights .............................. 5-99
Table 5.19
Transverse load on pole (kg/m per lb/ft of span length) ................ 5-103
Table 5.20
Load imposed by pole attachment ............................................. 5-105
Table 5.21
Minimum pole class to support vertical load ................................. 5-108
Table 5.22
Maximum span lengths for self-supporting cable .......................... 5-111
Table 5.23
Pole span length/tension .......................................................... 5-112
Table 5.24
Weight for ALPETH cable .......................................................... 5-113
Table 5.25
Cable weight for self-supporting cable ....................................... 5-115
Table 5.26
Cable weight for self-supporting cable reinforced sheath .............. 5-116
Table 5.27
Typical attachment clearances ................................................. 5-121
Table 5.28
Minimum vertical clearances of cables above ground or
rails at midspan crossing .......................................................... 5-125
Table 5.29
Minimum vertical clearance of cable runs along and
within limits of public highways ................................................. 5-125
Table 5.30
Strand sizes .......................................................................... 5-127
Table 5.31
Calculating pull when angle is known .......................................... 5-135
OSP Design Reference Manual, 4th edition
5-xii
© 2007 BICSI®
Chapter 5: Pathways and Spaces
Table 5.32
Minimum allowable tension for guys ........................................... 5-136
Table 5.33
Minimum guy strand selection table ........................................... 5-137
Table 5.34
Guy strand selection table ....................................................... 5-139
Table 5.35
Anchor groupings .................................................................... 5-142
Table 5.36
Soil classifications .................................................................. 5-146
Table 5.37
Anchor types recommended for different soil classes .................... 5-147
Table 5.38
Grades of construction for communications conductors ................. 5-150
Table 5.39
Standard pole settings ............................................................ 5-158
Table 5.40
Pole settings for solid rock below surface level ............................ 5-159
Table 5.41
Lengths of pole braces ............................................................ 5-190
Table 5.42
Maintenance hole ratings ......................................................... 5-200
Table 5.43
Maintenance hole window selection ........................................... 5-208
Table 5.44
Maintenance hole frames and covers ......................................... 5-216
Table 5.45
Precabling guidelines ............................................................... 5-228
Examples
Example 5.1
Tension worksheet form ............................................................. 5-43
Example 5.2
Conduit run layout .................................................................... 5-44
Example 5.3
Worksheet A to B (imperial and metric) ........................................ 5-46
Example 5.4
Worksheet B to A (imperial and metric) ........................................ 5-47
© 2007 BICSI®
5-xiii
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
OSP Design Reference Manual, 4th edition
5-xiv
© 2007 BICSI®
Chapter 5: Pathways and Spaces
Route Design
Introduction
The outside plant (OSP) designer should select routes to preclude the need for future pathway
relocation. Important factors to consider when planning a route include:
•
Safety.
•
Location.
•
Topography.
•
Local restrictions.
•
Cost.
•
Existing infrastructure
•
Future (i.e., proposed) development.
Preliminary Investigations and Surveys
Preliminary investigations and field surveys provide the designer with the information needed
to select pathways and spaces and prevent possible safety hazards. Before beginning
construction, the designer should consult available records and contact other utilities and
government agencies to determine existing or proposed facilities (e.g., power, fuel [oil, gas],
sewer, water mains, telephone, cable systems).
NOTE:
Natural gas and oil mains should be given special consideration because they
present fire hazards and potential liability.
If discrepancies are found between records and observable field conditions, the designer
should request verification from utilities and possibly use test holes to determine existing
conditions. When foreign lines, pipes, or structures (i.e., not appearing on the records) are
discovered, the designer should determine ownership and contact the owner.
If existing facilities present an obstacle, the designer may change the proposed route or
elevation.
Preliminary investigations also allow the designer to consider:
© 2007 BICSI®
•
Traffic conditions.
•
Building construction.
•
Road improvement or repair operations.
•
Landscaping.
•
Safety conditions.
•
Work site equipment access.
•
Future maintenance.
5-1
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Preliminary Investigations and Surveys, continued
Generally, when planning pathways, it is advisable to avoid:
•
Sewer catch basins.
•
Heavy traffic areas and possible future street locations.
•
Springs or underground streams.
•
Combustible gas or liquid storage facilities.
•
Existing underground utilities.
•
Aboveground structures and obstacles.
•
Foreign subsurface structures.
•
Surfaces that are difficult to restore.
•
Adverse soil conditions, including:
•
–
Environmentally sensitive areas.
–
Swamps.
–
Quicksand.
–
Unstable geological conditions.
–
Rock.
Areas with coastal or tidal restrictions.
During a field survey, prepare sketches and notes showing measured distances from curb,
centerline, or property lines to catch basins, sewer maintenance holes (MHs), hydrants, tracks,
utility cover plates, and other types of MHs. Notes should also be made of construction details
(e.g., railroad crossings, bridge attachments, and abnormal soil conditions) that might influence
the cost or feasibility of the proposed infrastructure.
Site Survey
Site survey is one of the most important parts of any project. It allows the designer to take the
time to look at the overall picture and resolve any possible conflicts that could delay or stop
the project. At this stage, the designer gathers general information about the existing OSP
conditions and begins to determine where the proposed OSP facilities will be placed. The
designer also draws detailed notes about the existing field conditions. Upon the completion of
this phase, all corrective information is also provided.
Route Construction
In planning for OSP cabling, cable infrastructure must be determined first. The choices are
aerial, direct-buried, and underground.
Typically, aerial plant (e.g., poles, cable, hardware, guys) has an expected life of approximately 30 years. Direct-buried plant has a similar or shorter lifespan, depending on different
conditions (e.g., the cable has no external protection from vermin damage or construction
unearthing other than its own sheath and armoring.)
OSP Design Reference Manual, 4th edition
5-2
© 2007 BICSI®
Chapter 5: Pathways and Spaces
Site Survey, continued
While being the most expensive system, underground plant usually has the highest cable
placement capacity (dependent on the number and size of conduits placed) and the longest
projected lifespan, typically in excess of 50 years. Despite the initial high cost, it is considered
the most economical route placement system over the span of its service life.
While the expected service life of the selected facility is a factor in route construction, so are
the expected technical capabilities. Rapid technology development outdates products quickly.
The designer must factor in the expected useful life of the design and advise the owner of the
latest developments. Ensuring a long life from a type of technology that has been bypassed by
newer developments may have little value. However, this is a decision the owner must make.
Prior to performing a site assessment for a customer, the designer should obtain permission
from the customer to work at the facility. If sensitive areas are involved, the designer should
determine specific security measures to satisfy customer requirements.
While performing the site survey for a current or potential customer, either for new
construction or overbuilds, it is important to discuss the aesthetic requirements of the job so
that both parties understand the expected end result (e.g., if open cuts are used to cross
streets, does the customer require repairing only the immediate path or replacing or repaving
an entire section).
While determining the proposed route for cable or conduit, the designer should discuss routing
with the customer. The customer may have reasons not to use the proposed route (e.g., future
plans for buildings and parking lots). Once the customer approves the proposed route, the
designer should identify splice or taper points for the new cable.
Even after the customer has approved the proposed route, the following field conditions may
force route changes:
© 2007 BICSI®
•
Adverse ground conditions
•
Coordination with other utilities
•
Missing easement or permits
•
Customer space utilization issues
•
Document errors or omissions
5-3
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Site Survey, continued
It is not always necessary to build new pathways for cable placement. The existing route may
be fully adequate. The designer should evaluate the existing:
•
Pole lines.
•
Conduit.
•
MHs.
•
Tunnels.
If space is available, these structures should be used to place the new cables, provided that
the customer owns the structures. If the customer does not own the structures, written
permission must be obtained from the owners before placement is made.
When selecting appropriate topology, the designer should involve the customer in discussions
to determine any geographic or special requirements. Any route selection involves tradeoffs. A
route that takes a new path may involve obtaining permits and licenses in addition to the costs
of construction. However, if the original route remains in service, it may provide diversity.
Following an existing route may provide the advantage of minimizing structural costs, but it
may not provide the most direct route. Consequently, the owner’s involvement is desirable.
Alternate Route Considerations
An alternative route may be considered if the field investigation indicates the proposed route
would be exposed to heavy traffic, expensive pavement replacement, adverse soil conditions,
or other factors that might create:
•
High installation costs.
•
Right-of-way (R/W) problems.
•
An unsafe working environment.
Except where safety is a concern, the designer should determine whether a change should
be made by deciding which is most cost efficient—the proposed route or an alternative route.
When selecting the most cost-effective route, consideration must be given to legal fees and
costs associated with delays due to the acquisition of permits, easements, and local approvals.
Even if the most direct route appears to require a greater initial cost (e.g., more excavation or
restoration costs), this cost should be weighed against that required for a longer route including
larger cable gauges, longer cable loops, and more splicing.
OSP Design Reference Manual, 4th edition
5-4
© 2007 BICSI®
Chapter 5: Pathways and Spaces
Flagging, Painting, and Marking Utilities
According to national and state laws in the U.S., for example, three days before excavation
can begin, a facility locating service must be ordered. The designer can also order this service
during the design phase to determine which utilities are in the excavation areas.
Small flags or color coded paint is used to mark the locations. The Common Ground Alliance
(CGA) recommends uniform color codes (see Table 5.1).
Table 5.1
Uniform color code for utility flagging, painting, or marking
The color…
Is used to identify…
White
Proposed excavation.
Pink
Temporary survey markings.
Red
Electric power lines, cables, conduit, and lighting cables.
Yellow
Gas, oil, steam, petroleum or gaseous materials.
Orange
Communications, alarm or signal lines, cables, or conduit.
Blue
Potable water.
Purple
Reclaimed water, irrigation, and slurry lines.
Green
Sewers and drain lines.
Test Holes (Potholes)
Obstacles located along the proposed route should be identified. Underground obstacles are
located using either electronic means or test holes.
A test hole is created by hand digging or using other noninvasive methods described in CGA’s
Best Practices. A test hole is a small hole either directly above or to the side of the obstacle’s
assumed position.
NOTE:
An undocumented utility may be an obstacle.
A test hole is located within the tolerance zone. This zone varies between 305 millimeters (mm
[12 inches (in)]) to 914 mm (36 in) from the marked obstacle. Local ordinances or state laws
should be checked for tolerances and advance notice requirements. If the zone is not
identified by law or code, the measured zone should be 457 mm (18 in) measured horizontally
from each side of the facility.
When an obstacle is located, a plan and profile drawing should be created to identify its
location. The route can be plotted using this information.
© 2007 BICSI®
5-5
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Documentation
A record should be made of the proposed route details (e.g., path, quantity, size, depth) with
references to a fixed point, showing the condition of road surfaces and various adjoining
structures. This record may be valuable if it becomes necessary to challenge future property
damage claims. A videotape record or dated and notarized photographs showing preinstallation
and postinstallation also may be useful for this purpose.
Right-of-Way (R/W)
When working on public or private R/W (see Chapter 8: Right-of-Way), necessary permits
and easements should be obtained before beginning construction. If construction is planned
on a:
•
Public R/W, permits should be obtained from an appropriate authority having jurisdiction
(AHJ [e.g., federal, state, county, city, or park]) for use of the proposed route.
•
Private R/W or easement, the right to use the property must be negotiated with each land
owner.
Joint Use Occupancy
To reduce the cost of multiple trenches and minimize the potential for damage to the existing
facilities, the telephone company, community antenna television (CATV), and power company
occasionally decide to dig a single trench and share it with one or all of the other parties. If
joint trenching becomes an option in a particular situation, refer to publications such as the
National Electrical Safety Code® (NESC®) for rules on cable separation.
NOTE:
Under a joint-use agreement, concordance of all involved parties should be established.
OSP Design Reference Manual, 4th edition
5-6
© 2007 BICSI®
Chapter 5: Pathways and Spaces
Pathways
Introduction
This section addresses design criteria that require attention by the designer when designing
OSP, including:
•
Underground pathways and spaces.
•
Direct-buried pathways and spaces.
•
Aerial pathways and spaces.
IMPORTANT:
No cutting that may affect a building structurally can be performed without
a prior approval by the architect/building owner. No structural members
can be cut or coring/sleeves installed without a prior approval by a
professional engineer licensed in the jurisdiction where the work is
performed.
Underground
The advantages of underground cable systems are that they:
•
Provide out-of-sight service and maintain the property’s aesthetic appearance.
•
Are adaptable for future facility placement or removal.
•
Provide additional physical cable protection.
The disadvantages of underground cable systems are that they:
•
Have a high initial installation cost.
•
Require more detailed route planning.
•
Provide a possible path for unwanted water or gases to enter buildings.
Direct-Buried
The advantages of direct-buried cable systems are that they:
© 2007 BICSI®
•
Provide out-of-sight service and maintain the property’s aesthetic appearance.
•
Have a low initial installation cost when compared to underground.
•
Can easily bypass obstructions.
5-7
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Direct-Buried, continued
The disadvantages of direct-buried cable systems are that they:
•
Are not flexible for future service reinforcements or changes.
•
Do not provide the same physical protection for the cable sheath as conduit.
•
May be difficult to locate in the case of all dielectric optical fiber cable.
•
Provide a possible path for unwanted water or gases to enter buildings.
Aerial
The advantages of aerial systems are that they:
•
Usually have the lowest installation costs.
•
Are readily accessible for maintenance.
The disadvantages of aerial systems are that they:
•
Are aesthetically displeasing.
•
Create potential clearance problems.
•
Are susceptible to environmental damage.
•
Are more susceptible to damage by the public, with potential liability to the owner.
•
May have a higher cost of ongoing maintenance.
OSP Design Reference Manual, 4th edition
5-8
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Underground Pathways
Introduction
Underground conduit structures are pathways used for placing telecommunications cable
between access points such as MHs, handholes (HHs), and building entrances.
Before selecting a route, the designer can perform a field survey to determine if any
construction problems exist and whether any cost savings could be realized by selecting a
different route. Sound judgment should be used when planning a conduit route to obtain the
best location for construction, maintenance, and cable placing and ensure the optimum design.
NOTE:
The shortest route is not necessarily the optimum design.
The number of ducts required in a proposed conduit system addition or extension depends on
the number of cables necessary to provide for the installed service and its expected growth
and maintenance. Cables required for growth may include facilities necessary to cutover and
relieve an existing cable that is at maximum capacity.
The designer should not attempt a detailed conduit system design until compiling and carefully
considering facts that might influence the final placement location. To allow ample time for
preliminary plan changes, necessary investigations should be performed well in advance.
The most desirable location for the conduit structure and MHs can be determined after a
careful review of the proposed main conduit routes, approximate MH locations, and
alternative routes. This data must be supplemented with field surveys and information obtained
from other subsurface users (i.e., other utilities). Every effort should be made to avoid
exposing or coming into contact with the existing underground facilities owned by other
utilities. In many areas, public utilities have developed underground facility damage prevention
systems. See Table 5.2 for locating center’s telephone numbers.
Table 5.2
Domestic and international one-call locate company telephone numbers
© 2007 BICSI®
Area
Phone Number
Region Covered
Alabama
800-292-8525
Statewide
Alaska
800-478-3121
Statewide
Arizona
800-782-5348
Statewide
Arkansas
800-482-8998
Statewide
California
800-227-2600
800-422-4133
North
South
Colorado
800-922-1987
or 800-833-9417
Statewide
Connecticut
800-922-4455
Statewide
Delaware
800-282-8555
or 800-441-8355`
Statewide
Florida
800-432-4770
Statewide
Georgia
800-282-7411
Statewide
5-9
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Introduction, continued
Table 5.2
Domestic and international one-call locate company telephone numbers, continued
Area
Phone Number
Region Covered
Hawaii
800-227-2600
Statewide
Idaho
800-626-4950
800-822-1974
800-428-4950
800-398-3285
800-424-5555
800-342-1585
Bonner, Boundary
Northern area
Kootenai
Shoshone and Benewah
Clearwater, Idaho, Lewis, and Nez Perce
All other counties
Illinois
800-892-0123
312-744-7000
Statewide except Chicago
Chicago
Indiana
800-382-5544
Statewide
Iowa
800-292-8989
Statewide
Kansas
800-344-7233
Statewide
Kentucky
800-752-6007
Statewide
Louisiana
800-272-3020
Statewide
Maine
888-344-7233
Statewide
Maryland
800-257-7777
800-282-8555
Eastern shore
Massachusetts
888-344-7233
Statewide
Michigan
800-482-7171
Statewide
Minnesota
800-252-1166
Statewide
Mississippi
800-227-6477
Statewide
Missouri
800-344-7483
Statewide
Montana
800-424-5555
800-551-8344
Statewide
Northwest
Nebraska
800-331-5666
Statewide
Nevada
800-227-2600
Statewide
New Hampshire
888-344-7233
Statewide
New Jersey
800-272-1000
Statewide
New Mexico
800-321-2537
888-526-0400
Statewide
Dona Ana, Lascruces
New York
800-962-7962
800-272-4480
Statewide except NYC and Long Island
NYC and Long Island
North Carolina
800-632-4949
Statewide
OSP Design Reference Manual, 4th edition
5-10
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Introduction, continued
Table 5.2
Domestic and international one-call locate company telephone numbers, continued
Area
Phone Number
Region Covered
North Dakota
800-795-0555
Statewide
Ohio
800-362-2764
or 800-925-0988
Statewide
Oklahoma
800-522-6543
or 800-654-8249
Statewide
Oregon
800-332-2344
Statewide
Pennsylvania
800-242-1776
Statewide
Rhode Island
888-344-7233
Statewide
South Carolina
888-721-7877
or 800-922-0983
Statewide
South Dakota
800-781-7474
Statewide
Tennessee
800-351-1111
Statewide
Texas
800-245-4545
800-344-8377
800-669-8344
Statewide
Statewide
Statewide
Utah
800-662-4111
Statewide
Vermont
888-344-7233
Statewide
Virginia
800-552-7001
Statewide
Washington
800-424-5555
Statewide
West Virginia
800-245-4848
Statewide
Wisconsin
800-242-8511
Statewide
Wyoming
800-849-2476
Statewide
District of
Columbia
800-257-7777
District-wide
Australia
61-3-9217-2833
Victoria, Tasmania, NSW, S. Australia,
Australian Capital and Northern
Western Australia
NSW, Australian Capital
Queensland
South Australia and Northern
61-8-9424-8116
61-2-9365-7582
61-7-3217-6332
08-8230-5024
© 2007 BICSI®
5-11
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Introduction, continued
Table 5.2
Domestic and international one-call locate company telephone number, continued
Area
Phone Number
Region Covered
Canada
800-242-3447
800-474-6886
800-400-2255
800-663-9228
866-828-4888
Alberta
British Columbia
Ontario
Quebec
Saskatchewan
Finland
011-358-09-271-1181
Republic of China
86-02-351-2345
Scotland
44-800-800-333
To enable optimum use of the conduit structure for subsequent cable placing operations,
particular care should be given to the MH locations and spacing. A conduit system should be
designed with a minimum number of horizontal and vertical directional changes. The ideal
structure is essentially straight runs between MHs with a grade drop for water runoff.
The designer can ensure a structure’s usefulness regardless of reel location by calculating the
expected pulling tensions for cable pulled from either direction and using the larger value for
design purposes. (See Section Length/Diameter Considerations for information regarding
conduit sizing and pull tension calculations.) Maximum lengths of cables that can be placed on
a reel should be considered when placing MHs.
Additionally, it is important for the designer to recognize that conduit bend locations and the
geometry of each bend (horizontal and vertical) are important factors to be considered
throughout the conduit design.
OSP Design Reference Manual, 4th edition
5-12
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Conditions Requiring Conduit Construction
The area to be served is typically determined by a needs assessment. When considering new
conduit, additions, or extensions, the designer should review the data that could cause changes
to the needs of the area to be served.
Conduit construction may be required when:
•
A pole line (existing or new) cannot support additional cable placement.
•
Specifically requested by government, property owner, or customer.
•
Direct-buried plant needs reinforcement if the construction corridor has limited space.
•
R/W limitations eliminate other choices.
•
An area is too congested to permit other construction methods.
•
Underground subdivision agreements forbid other types or methods.
•
Existing conduit is at capacity or is deemed unusable.
Once the need for conduit construction has been determined, the conduit route should be
designed so it provides the most direct and accessible route from the service feed. Factors
affecting route selection include:
•
R/W availability.
•
Topographical limitations (e.g., rock, sand, clay).
•
Land use and development (e.g., buildings, watersheds, storm/sewer drains).
•
Economic factors (e.g., R/W costs, congestion of utilities).
•
Joint-use potential.
•
Future R/W expansions.
•
Environmental impact limitations.
Economics
When conduit construction is required, the designer should design the most economical plant
possible, keeping in mind the costs associated with:
© 2007 BICSI®
•
R/W.
•
Materials (e.g., conduit, select backfill, concrete).
•
Labor, freight, and other costs that vary depending upon the jobsite location.
•
Subsurface conditions (e.g., rock, sand, obstructions).
•
Restoration of landscape.
•
Roads.
•
Railroads (RRs).
•
Water crossings.
•
Surface restoration.
•
Protection from traffic.
•
Type of duct formation.
•
Operations and maintenance expenses.
•
Environmental impact.
5-13
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Conduit System Planning
Conduit routes can be classified into two basic groups:
•
New routes (i.e., no existing conduit)
•
Existing routes (i.e., existing conduit and structure must be reinforced, expanded, or
extended)
Most design factors are the same in both an existing and new conduit route. However, when
planning to use an existing route, the designer must evaluate the existing MHs to determine if:
•
A safe working environment can be established.
•
The racking hardware can accommodate additional supporting hardware.
•
Sufficient room is available for splices cases or other additional hardware.
•
Entry is space available in the MH walls.
If MHs meet the above requirements and the existing route is used, the designer must decide
whether to place the conduit:
•
Above the existing conduit.
•
Beside the existing conduit.
•
At some distance from the existing conduit, using existing MHs as duct termination points.
•
Directional boring below existing facilities.
If the new structure is placed above or beside the existing conduit:
•
The ground cover must be capable of sustaining the expected loads (vehicular or
otherwise).
•
Must meet all applicable codes.
•
Municipal R/W restrictions must be satisfied, if required.
•
The existing conduit must not be damaged.
If bends are required, the designer must consider the increased pulling tension. Tension
calculations should be made before any design is finalized.
When an existing MH does not provide sufficient space and safe working conditions:
•
The existing MH may be rebuilt and/or expanded.
•
A new MH may be installed (at a new location).
OSP Design Reference Manual, 4th edition
5-14
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Finished Conduit System Design
The designer plans the conduit system and specifies the types and quantities of
material needed.
A finished design should consist of construction plans and specifications showing the:
•
Location of all existing and proposed conduit.
•
Size and configuration of MHs.
•
Total duct length (linear length multiplied by the number of ducts) of conduit (adjacent MH
wall-to-wall measurements).
•
Type of conduit material.
•
Special conduit fittings required.
•
Conduit (ductbank) formation and depth requirements.
•
Encasement specifications and materials.
•
MH or cable entrances.
•
Locations of any existing substructures.
•
Restoration requirements.
•
Required cuts (e.g., concrete, asphalt).
•
Location and depth of other structures (profile).
•
Traffic control plan.
Conduit System Requirements
The designer should determine the number of conduits to be placed in a proposed system
installation based on:
•
Initial requirements plus one maintenance conduit.
•
The estimated growth over the life cycle of the system.
•
Consultation with the owner or owner’s representative.
As part of the design process, the designer should also determine the inside diameter of the
conduit appropriate for the conduit system. Decreasing the diameter of the conduit run is not
advisable except where a branch (lateral) conduit run intersects with the main conduit route.
Other factors requiring consideration when determining the number of conduits to be placed in
a system include:
© 2007 BICSI®
•
Routing changes.
•
Special construction.
•
Public inconvenience caused by further expansion.
•
Other wire-using utilities (e.g., low-voltage systems, leased conduits).
•
Franchise agreements (e.g., city, fire, police).
•
Rearrangement of feeds to different areas.
5-15
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Conduit System Requirements, continued
When a main conduit run has two or more branches, the total number of branch conduits
(initial and estimated) may exceed the number indicated for the main conduit run. This may be
a result of using large cables in the main run as opposed to the smaller ones used in branch
runs.
Lateral/subsidiary conduits may be conduits that connect to structures (e.g., buildings,
pedestals, cabinets, poles). Lateral conduits are typically placed from the sidewall of a MH to
the structure. Subsidiary conduits are extended from the end wall of a MH along with the
main conduit run to feed a structure. This type of construction may be advantageous when the
location of future buildings is known. Examples of lateral and subsidiary conduits are
illustrated in Figure 5.1.
Figure 5.1
Lateral and subsidiary conduits
Bldg
A
Lateral
duct
MH
MH
Subsidiary duct
MH = Maintenance hole
At times, placing all of the conduits during the initial conduit system installation is desirable, if
not mandatory. Because they are difficult to access, all conduits should be placed during initial
installation when working at locations such as railroad crossings, bridges, and freeways.
OSP Design Reference Manual, 4th edition
5-16
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Future Conduit System Requirements
Customer demand for high-bandwidth transmission and the available technology to meet this
demand greatly affects the sizing of future conduit. Some of these changes include the:
•
Increased use of digital multiplexing technologies (e.g., T-1, T-3, E-1, and E-3). It reduces
the need for high pair count, twisted-pair cables which, in turn, may affect the conduit size
or number of conduits in a system.
•
Use of optical fiber cables may reduce conduit requirements.
•
Reclaiming of existing conduit systems. While this was a common practice for twistedpair cables (e.g., replacing a 1200 and a 1500 pair cable with a 2700 pair to regain a spare
duct or replacing a 1200 pair with an 1800 pair to gain 600 growth pairs), the use of a
spare 101 mm (4 in) duct to receive 32 mm (1.25 in) polyethylene (PE) or fabric mesh
innerduct for optical fiber cables allows existing routes to grow in capacity without
additional structural investment. The replacement of two or more smaller twisted-pair or
optical fiber cables, each in its own duct, with a larger cable in a single duct, reclaims duct
space for growth and avoids additional infrastructure investment.
Planning Lateral Ducts
When planning lateral ducts to distribution points, spare ducts for future use should be
provided. Lateral duct size is dependent on whether two or more ducts should be placed
between a MH and a terminating point (e.g., a building or pole.) A larger duct should be used
when placing one duct. Lateral duct length is limited by the size of the cable to be pulled into
it, the number of bends it will contain, and limitations by, for example, in the United States,
American National Standards Institute (ANSI) and local codes. Installing a minimum of one
spare is recommended.
© 2007 BICSI®
5-17
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Planning Subsidiary Ducts
If constructed at the same time as a main conduit run, place subsidiary ducts on top of the
main run. This is the most economical way of placing subsidiary ducts. It also affords some
top protection for the main run.
It is the designer’s responsibility to research the need for subsidiary ducts (e.g., planning for
future buildings). Subsidiary ducts are additional ducts required to house cables extending from
the main underground system to a pole or building. Subsidiary ducts can be:
•
Individual conduits.
•
Incorporated as part of a multiple duct structure.
When individual ducts are planned at the same time as the main conduit, they should be
positioned on top of the main conduit formation or, if applicable, in the side wall corner of the
MH.
However, the designer should try to avoid placing duct in side walls because such placement
reduces racking space and prohibits proper bending radii of large cables. If there is doubt
about the terminating point, place the subsidiary conduit as a continuous section from the MH.
When the subsidiary duct is part of a multiple-duct structure, the upper tiers of the structure
(preferably the corner ducts) should be designed for subsidiary use since they are more
readily accessible. Such design reduces excavating and restoration costs and uses less
subsurface space.
Conduit system arrangements should be compatible with MH cable racking arrangements and
are subject to:
•
Trench width and/or depth constraints imposed by terrain.
•
Presence of other structures.
•
Required working space.
Generally, 2-, 3-, or 4-wide conduit arrangements are preferred for single- or double-wall
racking. Where a large number of ducts or other circumstances require center racking and
wall racking, wider duct arrangements may be appropriate.
OSP Design Reference Manual, 4th edition
5-18
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Section Length/Diameter Considerations
The designer must determine the proper length of the conduit section. A primary objective of
conduit design is to make conduit section lengths as long as possible to reduce the number of
MHs, cable splices, and associated cable setups needed for construction.
The length of the conduit section will vary up to a maximum of 183 meters (m [600 feet (ft)]).
Section length considerations are based on:
•
The frequency and location of present and future subsidiary ducts and branch cables.
•
Load coil, build-out capacitor, and carrier equipment locations.
•
Subsurface obstructions located along the conduit route.
•
Conduit route intersections.
•
Cable cutting lengths from the manufacturer (i.e., splices are not allowed in conduits).
•
Maximum reel sizes and reel lengths.
•
The need for:
•
–
Intermediate MHs due to excessive cable pulling tensions caused by bends.
–
MHs for splicing based on the maximum available reel length of cable.
–
Maintaining a safe MH environment.
Applicable standards.
The designer must consider the facts pertinent to the route and exercise the best judgment in
each case.
Ducts must be large enough for a cable or cables to be pulled through the duct. As a rule of
thumb, the diameter of a duct should be at least 1.15 times the diameter of the cable, or onehalf trade size larger in diameter than the diameter of the largest anticipated cable, whichever
provides a greater clearance. It is the diameter of the pulling eye that is more important.
Cables are normally ordered from the cable manufacturer with the pulling eye installed. If not,
a core hitch is provided by the onsite crews for pulling cable.
Except for small cables, the diameter of the pulling eye (de) may be calculated as follows:
de < 1.1 dc
Where:
dc = cable diameter
© 2007 BICSI®
5-19
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Maintenance Hole (MH) Location and Quantity
The safety of personnel and the general public is a primary concern when selecting MH
locations. A desirable location will:
•
Provide a safe work area.
•
Allow for adequate traffic control when the MH is open (e.g., placing traffic warning
devices to alert motorists of upcoming construction).
•
Provide sufficient space for cable trailers and pulling trucks during construction.
•
Be suitable for placement, splicing, and maintenance of cables and associated equipment.
•
Not jeopardize vehicular or pedestrian traffic flow.
•
Be located out of the roadway when possible.
MHs should not be located in or near an intersection or near a curve in the road. Protection of
the work area at these locations is difficult.
The number of MHs built into a conduit run should be kept to a minimum. When planning MH
locations, the designer should:
•
Document MH locations on work drawings.
•
Locate MHs at junction points that permit installation of main and lateral or subsidiary
ducts with minimum bending.
Factors that may impact MH location include:
•
Municipal, county, state, or federal restrictions.
•
Surface water drainage into the MH.
•
Water table.
•
Public and worker safety (e.g., when MH is open).
•
Future street widening.
•
Provisions for cable placement.
•
Customer input.
•
Applicable standards.
Before installing/constructing a MH, the designer should investigate each proposed location to
determine subsurface conditions and the existence of foreign pipes or ducts. If unable to
determine subsurface conditions from the existing records and field observations or doubting
the subsurface conditions, the designer should order a test hole.
The test hole should be made diagonally across the proposed site and wide enough to ensure
clearance for the MH.
If foreign pipes or substructures are encountered during test hole or MH excavations, their
ownership should be immediately investigated. These pipes and substructures may be
removed if they are not in use with the owner’s permission. If the pipes and substructures
cannot be removed, the designer must decide whether to change the MH’s location or grade.
OSP Design Reference Manual, 4th edition
5-20
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Clearances
The minimum recommended separations between telecommunications conduit systems and
outside surfaces of foreign structures (see Table 5.3) are:
•
152 mm (6 in) when crossing pipes (e.g., gas, water, oil).
•
305 mm (12 in) when parallel to pipes (e.g., gas, water, oil).
For example, in the United States, the following clearances are required by the NESC.
Table 5.3
Clearances
Structure
Minimum Clearance
Power or other
76 mm (3 in) concrete foreign conduit
101 mm (4 in) masonry
305 mm (12 in) of well-tamped earth
Power conduit
Separate poles, if possible; if the same pole is used,
it should preferably be terminated on pole 180 degrees
but not less than 90 degrees.
Railroads
When crossing 1.27 m (50 in) below top of rail
Street railways
914 mm (36 in) below top of rail
in
m
mm
=
=
=
NOTE:
Inch
Meter
Millimeter
Check local authorities for applicable codes.
Conduit Depth
It is the designer’s responsibility to be aware of any unusual depth requirements that are
established for subsurface structures.
Installing conduit improperly can result in conduit deformations, sinking of the backfill, and
subsequent collapse of the road surface.
The 50-year frost line should be considered when calculating conduit depth.
The top of the conduit should be located at a sufficient depth (normally 610 to 762 mm
[24 to 30 in]) below surface grade so both live and dead loads can be sustained by the conduit
structure. Live or dynamic loads have a greater effect on conduit than dead or earth loads.
© 2007 BICSI®
5-21
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Live or Dynamic Loads
Live or dynamic loads are caused by vehicular traffic (see Figure 5.2) and result from the
combination of a vehicle’s weight and speed. It is assumed that they are transmitted through a
conical-shaped region extending downward from the point of application. The greater the
distance from the point of application, the greater the area over which the load is spread, and
the lower load per unit area. When conduits are located at least 1.83 m (6 ft) below grade, the
load is well dispersed.
Highway and road engineers usually work with specified loading conditions designated as
H-10, H-20, H-40, and so forth. The number refers to the maximum vehicular tonnage. For
design purposes, 80 percent of the weight is assumed to be concentrated on the rear axle. For
example, H-20 loading means that the roadway is built to accommodate a 20-ton vehicle with
80 percent or 14 515 kg (32,000 lb) per rear axle, assuming the vehicle has one rear axle.
Figure 5.2
Live or dynamic load dispersal
Load
Lines of
load dispersal
OSP Design Reference Manual, 4th edition
5-22
Depth
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Dead or Earth Loads
Dead or earth loads are created by the backfill and other aggregates. Dead loads are not
excessive when the amount of backfill measures 610 mm (24 in) or less; however, the exact
weight measurements vary with soil type (see Figure 5.3).
Figure 5.3
Dead or earth load dispersal
Lines of
load dispersal
Depth
Recommended conduit materials must be designed to withstand loads created by a normal
traffic flow when there is an adequate amount of fill between the top of the conduit structure
and ground surface. However, when the cover is smaller than recommended, additional
mechanical protection must be provided (e.g., a reinforced concrete slab placed above the
conduit structure.)
NOTE:
If concrete encasement is used, the reinforcing bars can be included along the base
of the encasements.
Tensile Stresses
Tensile stresses in the conduit structure can cause conduit units to separate at the joints.
The causes for tensile stresses include:
•
Trench irregularities.
•
Unstable soil conditions.
•
Conduit structure damage.
Placement of reinforcement bars within the concrete encasement, along the base of the
structure, could prevent these stresses.
© 2007 BICSI®
5-23
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Drain Slope
Installing underground conduit so that a slope exists at all points of the run allows drainage and
prevents the accumulation of water. A drain slope towards the MH from the center of the
conduit run or from the building of no less than 10 mm per meter (0.125 inches per foot).
Conduit Formations
Design conduit formations to facilitate orderly cable racking within the MH and ensure
minimal change in the formation when entering a MH. The following recommendations allow
for the design of the most efficient cable formation.
•
Preferably, main conduit formations should enter the end walls of the MH at a point
approximately halfway between the floor and ceiling.
•
For wall racking considerations, design splayed ductbank entrances at the end walls rather
than center placement (see Figures 5.89 and 5.90).
•
If the total number of conduits being placed is significantly less than the capacity of the
terminating MH or cable entrance, conduits should enter at the lowest level within the
MH. The upper space should be reserved for future conduit additions.
•
The conduit entrance into the MH should be sized for the ultimate number of conduits to
prevent the need for future wall breakouts.
OSP Design Reference Manual, 4th edition
5-24
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Conduit Formations, continued
Table 5.4 lists recommended conduit formations for up to 40 conduits at the MH entrance. If
more than 40 conduits are planned, special racking (center and wall) is recommended.
Table 5.4
Conduit formations
Number of Ducts
Using Conduit
Multiple Duct
4
2 wide by 2 high
One, 4-duct
6
3 wide by 2 high
One, 6-duct
8
4 wide by 2 high
Two, 4-duct
9
3 wide by 3 high
One, 9-duct
10
—
One, 6-duct and one, 4-duct
12
4 wide by 3 high
Two, 6-duct or three, 4-duct
15
—
One, 9-duct and one, 6-duct
16
4 wide by 4 high
Four, 4-duct
18
—
Two, 9-duct
20
4 wide by 5 high
Two, 6-duct and two, 4-duct
24
4 wide by 6 high
Four, 6-duct or two, 12-duct
28
4 wide by 7 high
—
30
—
32
4 wide by 8 high
—
36
4 wide by 9 high
Four, 9-duct (3 wide) or three, 12-duct
40
4 wide by 10 high
Four, 9-duct (3 wide) and one, 4-duct
Over 40*
—
—
* Investigate center racking possibilities
Advantages of Constructing Formations Using Individual Conduit
At times, conduit can be the best choice (see Tables 5.5 and 5.6) because it:
© 2007 BICSI®
•
Is lightweight. Mechanical handling equipment is not required.
•
Provides good joint integrity.
•
Produces a strong, stable structure if concrete encased.
•
Can be easily rearranged to avoid obstacles.
•
Can be pneumatically rodded.
•
Is available with bell end to allow ease of joint connection.
5-25
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Conduit Formations, continued
Table 5.5
Straight lengths of individual conduit
Weight kg/m (lb/ft)
Material
Length
Type B
Type C
Type D
Type E
Plastic
6 m (20 ft)*
0.3–0.6
0.6–0.7
0.5–0.8
N/A
(0.6–1.0)
(1.0–1.5)
(1.2–1.7)
*Longer and shorter lengths available from manufacturer
Type B (thin wall) requires concrete encasement.
Type C (thick wall) may be direct-buried with selected backfill in straight runs.
Type D is ultraviolet (sunlight) and flame resistant.
ft = Foot
m = Meter
NOTE:
Type E is not used for straight line conduit.
Table 5.6
Rigid bends for 100 mm (4 trade size) individual conduit
Material
Angle (Degrees)
Radius
Length
B, C, or D Plastic
7
30***
30***
45***
45***
45***
90***
4.6 m (15 ft)
4.6 m (15 ft)
3.7 m (12 ft)
2.74 m (9 ft)
2.74 m (9 ft)
0.91 m (3 ft)
0.91 m (3 ft)
0.71 m (2.33 ft)
2.54 m (8.33 ft)
2.06 m (6.76 ft)
2.31 m (7.58 ft)
1.60 m (5.25 ft)
0.86 m (2.82 ft)
1.60 m (5.25 ft)
E Plastic*
90**/***
64***
0.91 m (3 ft)
0.91 m (3 ft)
1.83 m (6 ft)
1.17 m (3.84 ft)
*
Replaces cast iron for subsidiary conduit
**
Also available in split form for repairs
***
Requires concrete encasement
ft = Foot
m = Meter
OSP Design Reference Manual, 4th edition
5-26
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Advantages of Multiple-Bore Conduit
In some situations, using multiple-bore conduit is advantageous since it does not require:
•
Long trench openings.
•
Select backfill.
•
Ready-mix concrete.
Types of Conduit
Types of conduit include:
•
EB-20—For encasement in concrete.
•
EB-35—For encasement in concrete.
•
DB-60—For direct burial.
•
DB-100—For direct burial.
•
DB-120—For direct burial.
•
Rigid nonmetallic conduit Schedule 40—For direct burial or encasement in concrete.
•
Rigid nonmetallic conduit Schedule 80—For direct burial or encasement in concrete.
•
Multiple plastic duct (MPD)—For direct burial or installation in conduit.
•
Rigid metal conduit—For direct burial or encasement in concrete.
•
Galvanized rigid steel conduit—For direct burial.
•
Intermediate metal conduit—For direct burial or encasement in concrete.
•
Fiberglass duct—For direct burial or encasement in concrete.
•
Innerduct polyvinyl chloride (PVC)—For installation in conduit.
•
Multiple celled conduit—For optical fiber and other small diameter cables.
•
High-density polyethylene (HDPE) roll pipe—Directional boring or direct buried.
•
Other specialty conduits.
NOTES: Encased buried and direct-buried must meet the requirements of the National
Electrical Manufacturers Association® (NEMA®) TC-6 and TC-8.
Schedule 40 and Schedule 80 rigid nonmetallic conduit must meet the requirements
of NEMA TC-2.
NEMA TC-10 covers telecommunications Type B and D.
Additional specifications can be found in the American Society for Testing and
Materials (ASTM) F512-06, Standard Specification for Smooth-Wall (Polyvinyl
Chloride [PVC]) Conduit and Fittings for Underground Installation.
These conduit classifications differ based on the type of material and the pipe wall thickness.
Thin-walled conduit may require encasement in concrete to protect the structure from being
crushed by traffic load or from dead load from the earth. Conduit with a thicker wall may be
direct-buried. However, if it cannot be buried deeply enough, it may also be encased in
concrete. Once built, the conduit should remain usable for 75 to 100 years and fulfill design
specifications.
© 2007 BICSI®
5-27
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Selecting a Type of Conduit
Selecting the appropriate conduit material can combine favorable first-cost and long-term
serviceability for each specific job. To make the best possible decision, the designer must
consider numerous factors, including cost, especially when pavement demolition and
restoration is involved.
In locations where:
•
The expense of pavement demolition and restoration is considerable, material that lends
itself to narrow, deep formations, should be used.
•
Soil is loose or wet, a shallow or wide formation is desirable.
•
Numerous changes in direction are anticipated and rolling or splitting of the formation is
required, single-bore conduit generally provides the best facility to avoid subsurface
obstructions.
Other factors that affect the selection of conduit materials include:
•
Job specifications.
•
Local codes.
•
Material cost.
•
Local availability.
•
Ease of handling.
•
Ease of joining.
•
Concrete encasement requirements (e.g., curves, bends, elevation changes, specified road
crossings).
•
Backfill requirements.
•
Soil conditions.
•
Special conditions (e.g., heat, gas, loads, chemical environments, limited cover).
NOTE:
Some factors may be unique to the conduit material.
OSP Design Reference Manual, 4th edition
5-28
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Selecting a Type of Conduit, continued
Galvanized Rigid Steel Conduit
Galvanized rigid steel conduit is intended only for use in locations where other materials are
not suitable.
Galvanized rigid steel is the recommended choice when:
•
Vertical space available for conduits is limited.
•
Conduit will be subjected to impact loads from heavy traffic.
•
Conduit is to be placed by a pipe pusher.
•
Conduit is to be preformed and lowered into the bed of a stream or river.
•
Environmental conditions are too severe for other types of conduit.
•
Designing submarine crossings.
Galvanized rigid steel conduit used in telecommunications conduit construction must meet the
following requirements:
•
The conduit must be made from soft, weldable quality steel suitable for bending.
•
The hot-dipped zinc coating (galvanization) placed on the interior of the conduit must be
smooth and free from:
–
Blisters.
–
Projections.
–
Other defects.
–
The weight of the zinc coating on the interior and exterior surfaces should not be less
than 6.1 grams (g) per square decimeter (dm2 [2.0 ounces (oz) per square foot (ft2)])
of total coated surface.
Galvanized pipe for ordinary uses (e.g., water pipe) does not meet requirements for use in
telecommunications systems. Commercial electrical conduit does not have the required weight
of zinc coating on the outside surface and there may be no zinc coating on the interior surface.
© 2007 BICSI®
5-29
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Selecting a Type of Conduit, continued
Galvanized rigid steel conduit is available in all commercial sizes with or without threaded ends
and couplings. Table 5.7 indicates example sizes. Verify with manufacturer’s actual sizes.
Table 5.7
Galvanized rigid steel conduit sizes
Trade
Size
Plain End
OD mm (in)
ID mm (in)
1
33.53 (1.32)
26.67 (1.05)
1-1/2
48.26 (1.90)
40.89 (1.61)
2
60.45 (2.38)
52.58 (2.07)
3
88.90 (3.50)
77.98 (3.07)
3-1/2
101.60 (4.00)
90.17 (3.55)
4
114.30 (4.50)
102.36 (4.02)
ID
in
mm
OD
=
=
=
=
NOTE:
Inside diameter
Inch
Millimeter
Outside diameter
BICSI’s recommended size for galvanized rigid steel is trade size 4.
A disadvantage of steel conduit is that it tends to choke current flow in a cable. To overcome
this choke effect, the steel conduit must be bonded to the cable shield at both ends of the
conduit run. Refer to Chapter 7: Grounding, Bonding, and Electrical Protection.
Conduit Construction
Past conduit construction methods have contained joints that allowed silt to leak into the duct.
In many instances, this duct must be cleaned in a process commonly called rodding and
mandreling, before cables can be installed. In some cases, dig-ups may be required to clear
obstructions. To prevent these types of expenses, certain operational considerations should be
examined when selecting conduit material, including the:
•
Conduit’s susceptibility to silting.
•
Coefficient of friction as it affects cable pulling tensions.
•
Smoothness and strength of bends or grade changes to minimize winch-line cutting.
•
Encasement.
OSP Design Reference Manual, 4th edition
5-30
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Conduit Construction, continued
Conduit with poorly made joints, or joints that open while in service, eventually become fouled
with silt, a condition that becomes progressively worse over time. Proper installation
procedures prevent this and limit the amount of water ingress to the system. This minimizes
the opportunity for corrosion, primarily in MHs, and reduces MH maintenance in areas where
the water table is high.
It is recommended to transition to PVC from HDPE prior to terminating conduit into a MH.
Rodding by mechanical or manual means is required in case of minor obstructions or slight
misalignments (e.g., in multiple clay or concrete conduit). Where conduit is broken, it must be
unearthed and repaired. Plastic conduits having substantially airtight joints between MHs can
be rodded with compressed air systems. Investment for equipment is lower than that required
for mechanical rodding, and costs per conduit length are generally more economical. Rodding
costs vary depending on the condition of the conduits and the methods employed.
Using Innerduct
The use of innerduct will enhance conduit capacity and utilization for optical fiber and smaller
balanced twisted-pair cable placement. Innerduct allows a maximum number of cables to be
placed in various types of conduit systems.
Innerduct comes in standard corrugated PE or PVC type pipe, typically with 25 or 32 mm
(1 or 1.25 in) diameter. The corrugated design facilitates easy wire pulling, and its flexibility
eliminates the need for bending equipment.
A fabric mesh type of innerduct, which can further increase a duct system’s cable placement
capacity, is also available. The fabric mesh has a smaller duct fill rate footprint compared with
standard innerduct and is designed to minimize pulling tensions.
© 2007 BICSI®
5-31
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Conduit Construction, continued
Each innerduct should be equipped with a pull rope or tape. A tracer wire can be installed in
the innerduct to aid in cable locating requirements.
Advantages of traditional innerduct include:
•
Enhanced mechanical protection.
•
Compartmentalize conduit.
•
Ease of identification.
Disadvantages of traditional innerduct include:
•
Higher material cost.
•
Limited cable size.
•
Increased installation time.
Advantages of fabric mesh innerduct include:
•
Increased conduit utilization.
•
Decreased pulling tensions.
•
Conforming to odd-shaped spaces.
Disadvantages of fabric mesh innerduct include:
•
Higher material cost.
•
Becoming twisted if not placed according to manufacturers’ specifications.
•
Bonding to the conduit because of adverse environmental contaminations.
OSP Design Reference Manual, 4th edition
5-32
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Conduit Construction, continued
Conduit Casings
It may be a requirement to place conduit in large steel tubes (casings) as a means of
protection or to facilitate a crossing where an open trench cannot be provided (e.g., at
railroads, major state highways or freeways, river or stream crossings). For additional
requirements on casing lengths, refer to Chapter 8: Right-of-Way.
This type of protection usually requires that the tubing is placed by boring. It is an expensive
operation and should be specified only when other methods are not practical.
Typical installations under railroads and highways are shown in Figures 5.4 and 5.5. Local
AHJs should be contacted regarding specific measurements, including wall thicknesses and
conduit specifications.
Figure 5.4
Conduit casings under railroads
7.6 m (25 ft)
7.6 m (25 ft)
Ditch
0.91 m
(3 ft)
Roadbed
0.91 m (3 ft)
CL
CL
Track
Track
1.4 or 1.7 m
(4.5 or 5.5 ft)
0.91 m
(3 ft)
1.7 m
(5.5 ft)
Sand fill
Conduits
Casing
CL = Center line
ft = Foot
m = Meter
NOTE:
© 2007 BICSI®
After conduit installation is complete, casings should be filled with fine sand, blown
in under air pressure, and sealed at both ends with a 76 mm (3 in) concrete wall.
5-33
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Conduit Construction, continued
Figure 5.5
Conduit casings under highway
Roadway structure
1.52 m
(5 ft)
Roadway
Shoulder
Pavement
Unpaved
ditch
Base
1.28 m (4 ft)
Subbase
0.91 m (3 ft)
0.91 m (3 ft)
Conduits
Casing
ft = Foot
m = Meter
NOTE:
Sand fill is optional.
Thick-wall plastic and concrete conduit requires encasement only when:
•
Subject to heavy vehicular traffic.
•
Placed in unstable soil conditions.
•
A high soil compaction is required (85 percent or greater).
•
A minimum 762 mm (30 in) cover cannot be maintained.
Thin-wall plastic must always be encased in concrete or some type of approved stable
sleeving.
Wall Thickness of Casing Pipe
The wall thickness of a casing pipe is dependent on several factors such as the:
•
Live or dynamic load from vehicular traffic.
•
Dead or earth load.
•
Diameter of the casings used.
NOTE:
Casing walls must be at least 4.8 mm (0.19 in) thick.
OSP Design Reference Manual, 4th edition
5-34
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Calculating Conduit Pulling Tensions
The designer should understand that the quantity of tension that can be used to pull cables into
a length of duct is limited. The tension limit is based on either the winch line strength or the
cable strength.
Some cable pulling lubricant manufacturers provide software programs that calculate pulling
tension.
Cable strength, also known as the maximum recommended installation load (MRIL), is the
load a particular cable can withstand without experiencing electrical or mechanical
degradation. MRIL is based on the conductor strength within the cable sheath and must be
obtained from the manufacturer for each type of cable to be installed in the conduit system.
Pulling tension should be constantly monitored when using a mechanical pulling device (e.g., a
winch or tugger). The mechanical pulling device should be equipped with a tension meter or
dynamometer. The pulling device should be placed between the cable head and the power
winch and should be monitored throughout the pulling operation. This pulling device should be
equipped with a limit clutch to adjust tension. The maximum pulling tension specified by the
cable manufacturer must never be exceeded. The maximum pulling tension must not exceed
the rated working load for the winch cable. For 11.9 mm (0.47 in) nonrotating wire ropes, the
maximum pulling tension is 28.91 kilometers (kN [6500 pounds force (lbf)]).
Winch line tension fluctuates during cable pulling operations and may reach peak values
greater than the average cable pulling tension. Conduit section length for large conduits
(i.e., 100 mm [4 trade size] or larger) should be designed so that the maximum calculated
cable-pulling tension never exceeds 28.91 kN (6500 lbf). Refer to the cable manufacturer’s
recommended pulling tensions for the specific cable.
In a conduit run composed of an arbitrary succession of straight lines and bends, two basic
equations, when applied in a step-by-step fashion, can be used to calculate the cable tension at
any point in a conduit run.
Calculations for bends should include changes in horizontal and vertical direction. For a large
cable, the tension (T) required to maintain a steady motion at any point on the cable and winch
line can be expressed in terms of the:
•
Coefficient of friction (f) between the cable and the conduit segment.
•
Tension (T0) at the feed end of the segment.
•
Weight (w) per unit length of the cable or winch line.
•
Geometry of the segment.
Since cable can be pulled into the conduit from either direction, the greater pulling tension
value should always be considered when designing conduit section lengths. Keep in mind that
the cable pull tension stated by the manufacturer is the point at which the cable’s performance
characteristics are altered. Cable tensile strength is the point where the cable is pulled apart.
© 2007 BICSI®
5-35
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Calculating Conduit Pulling Tensions, continued
Coefficient of Friction (f)
The coefficient of friction (f) is the ratio of force needed to pull the cable through the conduit
to the force that is normal to the plane of the conduit. In a horizontal plane, the normal force is
equal to the total weight of the cable section. Field measurements of pulling tensions suggest
the coefficients of friction shown in Table 5.8. Factors that affect the coefficient of friction
include:
•
Dirt or contamination.
•
Type of surface.
•
Lubrication of cable.
•
Conduit deviations.
•
Conduit deformations.
•
Placement of setup equipment.
Calculations assume the conduit will be relatively free of silt and other obstructions at the time
the cable is placed. Unless otherwise indicated, all cable identified in this manual is HDPE. It
should be noted, however, that cable manufacturers today are producing more low-density
polyethylene (LDPE) than HDPE.
Table 5.8
Coefficient of friction
Coefficient of Friction
High-Density
Polyethylene
Low-Density
Polyethylene
Conduit Material
Dry
Lubricant
Dry
Lubricant
Polyvinyl chloride
0.31
0.13
0.36
0.16
Concrete
0.48
0.37
0.57
0.41
Corrugated plastic
0.22
0.13
0.40
0.13
NOTE:
Coefficients of friction are unitless and work in both metric and imperial
calculations.
Optical fiber cable is usually pulled into a smooth bore or corrugated duct, or fabric mesh, all
of which are commonly known as innerduct. The coefficient of friction for pulling lubricated
cable into a:
•
Smooth bore innerduct is 0.25.
•
Corrugated innerduct is 0.20.
•
Fabric mesh innerduct is 0.16
.
When installing optical fiber cable, use suitable innerduct to maximize the length of optical
fiber cable that can be placed in a single pull.
OSP Design Reference Manual, 4th edition
5-36
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Calculating Conduit Pulling Tensions, continued
Calculating Pulling Tension for Straight Horizontal Conduit
The pulling tension necessary to pull a cable through a straight horizontal conduit can be
calculated using the following equation:
T = T0 + f w s
Where:
T is pulling tension required at the point of interest (N or lbf);
T0 is the holdback tension at some reference point, usually the beginning of the
straight section. This is the tail load at the reel if the point considered is in the first
segment from the reel location. For large conduits, a value of 890 newtons
(N [200 lbf]) is considered a reasonable value for the tail load;
f is coefficient of friction between the cable and the conduit;
w is weight per unit length of cable in newtons per meter (N/m) or pounds per foot
(lb/ft). For imperial measurement units, cable weight in pounds (lb) is the same as
the force of its weight in lbf. For metric units, cable weight in kilograms (kg) must
be converted to the force of its weight by multiplying it by 9.8 newtons per
kilogram (N/kg); and
s is the distance from the reference point to the point of interest in m or ft.
Figure 5.6 illustrates the forces that act on the cable when pulled steadily through a straight
segment of conduit.
Where:
Fr is frictional force between the cable and conduit (Fr = f w s).
Figure 5.6
Forces acting on cable pulled through straight conduit
T
T
0
Pulling direction
Fr
© 2007 BICSI®
5-37
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Calculating Conduit Pulling Tensions, continued
Application of this equation is illustrated in the following basic example.
PROBLEM:
Determine the maximum pulling tension that can be expected when a DCMZ24 cable (11.3 kg/m [7.6 lb/ft]) is pulled into a 30.5 m (100 ft), straight,
horizontal section of plastic conduit without lubricant.
SOLUTION:
Assuming a tail load of 890 N (200 lbf) is caused by the friction of the cable
reel supports, and using the coefficient of friction of 0.31 from Table 5.8, the
calculation is as follows:
T = T0 + f w s
T = 200 + (0.31 × 7.6 × 100)
T = 436 lbf
In metric units:
T = 890 + [0.31 × (9.8 × 11.3) × 30.5]
T = 1937 N
NOTE:
Final answers should be rounded to two significant digits.
Calculating Pulling Tension for Inclined Straight Segment of Conduit
For inclined straight conduit (as in Figure 5.7) segment, the pulling tension can be calculated
using Equation 1, as follows:
T = T0 + w (f x ± h)
Where:
T, T0, f, and w are the same as defined in the simple horizontal case above;
x is horizontal projection of segment; and
h is vertical projection of segment (h is positive for an increase in elevation, h is
negative for a decrease in elevation, and h is zero for no change in elevation).
NOTES:
Use trigonometric formulas to relate s, h, and x.
The total length, s, of the segment is equal to x 2 + h 2 .
For level conduit having only shallow slope for conduit drainage, it may be
acceptable to ignore h.
OSP Design Reference Manual, 4th edition
5-38
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Calculating Conduit Pulling Tensions, continued
Figure 5.7
Inclined straight conduit
T
s
h
T
0
x
Calculating Pulling Tension for Uniformly Curved Segment of
Conduit
The basic equation applying to a uniformly curved segment of conduit is Equation 2 (often
called a “capstan” equation):
T = w r sin h {sin h-1 [T0 / (w r)] + f θ / 57.3}
Where:
T, T0, f, and w have the same meaning as in Equation 1 and;
r is radius of curvature of the simple bend in m or
ft (see Figure 5.8);
s is arc length of bend in m or ft; and
θ is displacement angle in degrees (θ = s / r = 57.3)
© 2007 BICSI®
5-39
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Calculating Conduit Pulling Tensions, continued
Figure 5.8 Simple bend
Conduit
B
s
r
Radius of
curvature
A
Displacement
angles
Simple bend
A cable-pulling tension table was constructed from this formula and can be used to determine
the tension that develops in a conduit bend. Table 5.9 lists the results of the trigonometric
functions sin h and sin h-1 used in Equation 2. Equation 2 is modified to simplify the terms:
T = w r sin h {sin h-1 [T0 / (w r)] + (f θ / 57.3)}
T / (w r) = sin h {sin h-1 [T0 / (w r)] + (f θ / 57.3)}
PTR = sin h [sin h-1 (BTR) + RUB / 57.3]
Where:
PTR (pulling tension ratio) = T / w r
BTR (back tension ratio) = T0 / w r
RUB (resistance under bend) = f θ
To use the following table:
1. Calculate BTR and RUB.
2. Look up the result PTR in Table 5.9. If not using interpolation with this table, round BTR
and RUB up to the closest higher value for a worst-case result.
3. Calculate the pulling tension T = (w r) PTR.
NOTE:
Using interpolation with this table will provide a more accurate result.
A scientific calculator may be used to calculate the result from Equation 2.
OSP Design Reference Manual, 4th edition
5-40
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Calculating Conduit Pulling Tensions, continued
Table 5.9
Cable pulling tension
RUB
PTR
0
BTR
5
10
15
20
25
30
35
40
45
50
55
60
65
70
0.2 0.29
0.38
0.48
0.58
0.68
0.79
0.90
1.02
1.15
1.29
1.44
1.59
1.76
1.95
0.4 0.50
0.60
0.70
0.81
0.92
1.05
1.18
1.32
1.47
1.63
1.80
1.99
2.19
2.41
0.7 0.81
0.92
1.05
1.18
1.32
1.47
1.63
1.80
1.99
2.19
2.41
2.65
2.90
3.18
1.1 1.23
1.38
1.53
1.70
1.88
2.07
2.28
2.50
2.75
3.01
3.30
3.62
3.96
4.33
1.8 1.99
2.19
2.41
2.64
2.90
3.18
3.48
3.81
4.17
4.56
4.99
5.45
5.96
6.51
2.8 3.07
3.36
3.68
4.03
4.41
4.82
5.27
5.76
6.29
6.87
7.50
8.19
8.95
9.77
4.5 4.92
5.38
5.88
6.42
7.01
7.66
8.36
9.13
10.0
10.9
11.9
13.0
14.1
15.4
6.5 7.10
7.75
8.47
9.24
10.1
11.0
12.0
13.1
14.3
15.6
17.1
18.6
20.3
22.2
9.3 10.2
11.1
12.1
13.2
14.4
15.7
17.2
18.7
20.4
22.3
24.3
26.6
29.0
31.6
12.0 13.1
14.3
15.6
17.0
18.6
20.3
22.1
24.2
26.4
28.8
31.4
34.2
37.4
40.8
16.0 17.5
19.1
20.8
22.7
24.8
27.0
29.5
32.2
35.1
38.3
41.8
45.6
49.8
54.3
20.0 21.8
23.8
26.0
28.4
31.0
33.8
36.9
40.2
43.9
47.9
52.3
57.0
62.2
67.9
24.5 26.7
29.2
31.8
34.7
37.9
41.4
45.1
49.3
53.7
58.7
64.0
69.8
76.2
83.2
30.0 32.7
35.7
39.0
42.5
46.4
50.6
55.3
60.3
65.8
71.8
78.4
85.5
93.3
102
37.0 40.4
44.1
48.1
52.5
57.2
62.5
68.2
74.4
81.2
88.6
96.6
105
115
126
45.0 49.1
53.6
58.5
63.8
69.6
76.0
82.9
90.5
98.7
108
118
128
140
153
54.0 58.9
64.3
70.2
76.6
83.5
91.2
99.5
109
118
129
141
154
168
183
65.0 70.9
77.4
84.5
92.2
101
110
120
131
143
156
170
185
202
221
77.0 84.0
91.7
100
109
119
130
142
155
169
184
201
219
239
261
89.0 97.1
106
116
126
138
150
164
179
195
213
232
254
277
302
100 109
119
130
142
155
169
184
201
219
239
261
285
311
339
PTR
BTR = Back tension ratio
PTR = Pulling tension ratio
RUB = Resistence under bend
© 2007 BICSI®
5-41
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Calculating Conduit Pulling Tensions, continued
The following explains the use of Table 5.9.
PROBLEM:
Determine the maximum pulling tension that can be expected when a DCMZ24 cable (w = 11.3 kg/m [7.6 lb/ft]) is pulled into a 30.5 m (100 ft) curved
horizontal segment of plastic conduit having a displacement angle of 70
degrees. No lubricant is used so the coefficient of friction is 0.31, and the tail
load is assumed to be 890 N (200 lbf).
1. Calculate the bending radius:
If q = 57.3 (s / r)
Then r = 57.3 (s / θ) = 57.3 (100/70) = 82 ft
Calculate the back tension ratio:
BTR = T0 / (w r) = 200 / (7.6 × 82) = 0.32
Calculate the resistance under bending:
RUB = f q = 0.31 × 70 = 21.7
2. Look up the pulling tension ratio from the table (the closest higher entry is BTR = 0.4 and
RUB = 25.0):
PTR = 0.92
3. Calculate the tension:
T = (w r) PTR = 7.6 × 82 × 0.92 = 573 lbf
In metric units:
1. r = 57.3 (30.5 / 70) = 25 m
BTR = 890 / (9.8 × 11.3 × 25) = 0.32
RUB = 21.7
2. BTR = 8.92
3. T = 9.8 × 11.3 × 25 × 0.92 = 2547 N
NOTE:
BTR, RUB, and PTR are unitless. Except for soft conversion variations, these will
be the same as the imperial calculations.
Cumulative Tension Worksheet
A worksheet (see Example 5.1) can be used for calculating the cable tension as it
accumulates through each segment of the conduit run.
OSP Design Reference Manual, 4th edition
5-42
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Calculating Conduit Pulling Tensions, continued
r
w
PTR
r
BTR
h
x
f
T
0
w
T0 + w [(fx) ± h] =
Straight Segment
T
f
fq =
q
RUB
T
0
w
T0/(wr) =
Curved Segment
PTR (wr) =
T
Example 5.1
Tension worksheet form
© 2007 BICSI®
5-43
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Calculating Conduit Pulling Tensions, continued
A step-by-step use of this method can best be described in the following example using
Equation 1, the table, and the worksheet. A layout is shown in Example 5.2.
Example 5.2
Conduit run layout
r = 18.3 m (60 ft)
61 m (200 ft)
30°
A
45.8 m (150 ft)
r = 12 m (40 ft)
B
40°
30.5 m (100 ft)
° = Degree
ft = Foot
m = Meter
PROBLEM:
Determine the pulling tension on a DCMZ-24 cable (11.3 kg/m [7.6 lb/ft])
being pulled into a horizontal plastic conduit run from point A to B. Assume a
tail load of 890 N (200 lbf) and a friction coefficient of 0.31. See worksheets
A to B (see Example 3.3) and B to A (see Example 3.4).
1. Determine the pull tension on the cable for the first segment as it reaches the end of the
200 ft straight segment of conduit.
T = T0 + f w s = 200 + (0.31 × 7.6 × 200) = 671 lbf
This is entered as the first straight segment tension and as the first curved segment T0
(both in the first row of the table).
2. Calculate the resistance under bending:
RUB = f θ = 0.31 × 30 = 9.3
Using the value of tension from Step 1, find the back tension ratio for the 30° curved
segment.
BTR = T0 / (w r) = 671 / (7.6 × 40) = 2.2
From the table (using RUB = 10, BTR = 2.8):
PTR = 3.36
T = (w r) PTR = 1021 lbf
This is entered as the first curved segment tension (in the first row) and as the second
straight segment T0 (in the second row).
OSP Design Reference Manual, 4th edition
5-44
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Calculating Conduit Pulling Tensions, continued
3. As the cable enters the 150 ft straight segment, T0 = 1021 lbf.
T = T0 + f w s
T = 1021 + (0.31 × 7.6 × 150)
T = 1374 lbf
This is entered as the second straight segment tension and as the second curved segment
T0 (both in the second row of the table).
4. Calculate the resistance under bending:
RUB = f q
RUB = 0.31 × 40
RUB = 2.4
Using the value of Step 3, find the back tension ratio for the 40-degree curved segment.
BTR = T0 / (w r)
BTR = 374 / (7.6 × 60)
BTR = 3.0
From the table (using RUB = 15, BTR = 4.5):
PTR = 5.88
T = (wr) PTR
T = 7.6 × 60 × 5.88
T = 2681 lbf
This is entered as the second curved segment tension (in the second row) and as the third
straight segment T0 (in the third row).
5. As the cable enters the 100 ft straight segment, T0 = 2681 lbf.
T = T0 + f w s
T = 2681 + (0.31 × 7.6 × 100)
T = 2917 lbf (rounded to two significant digits)
This is the final pulling tension. If the direction of pull were reversed, the pulling tension at
A would have been 2107 lbf (see Example 5.3). Since the cable can be pulled into the
conduit from either direction, the greater pulling tension must be assumed for this conduit
system. Installers should use the lower direction, if possible.
© 2007 BICSI®
5-45
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Calculating Conduit Pulling Tensions, continued
Example 5.3
Worksheet A to B (imperial and metric)
Imperial
Straight Segment
Curved Segment
T = T0 + fws
T0
w
f
T0 /(wr) =
fq =
h
s
T
q
f
200
7.6
0.31 200
0
671
0.31
30
1021
7.6
0.31 150
0
1374
0.31
40
2680
7.6
0.31 100
0
2917
RUB
9.3
T0
671
12.4 1374
PTR(wr) =
BTR
w
r
7.6
40
2.2
7.6
60
3.0
T
PTR
w
r
3.36
7.6
40
1021
5.88
7.6
60
2681
Metric
Straight Segment
T0 = w [(fx) ± h] +
T0
w
T
x
h
890 111
0.31 61
0
4476 111
0.31 45
11750
0.31 30.5
111
f
NOTE:
Curved Segment
fq =
RUB
q
f
T0 /(wr) =
T0
w
PTR(wr) =
BTR
r
PTR
r
w
T
2989 0.31
30
9.3
2989
111
12
2.2
3.36
111
12
4476
0
6024 0.31
40
12.4
6024
111
18
3.0
5.88
111
18
11750
0
13000
Many manufacturers of pulling lubricants offer online or direct assistance in calculating expected pulling tensions. Software programs can also be purchased from
them.
OSP Design Reference Manual, 4th edition
5-46
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Calculating Conduit Pulling Tensions, continued
Cable pulling tension should also be calculated for pulling in the opposite direction (see
Example 5.4)
Example 5.4
Worksheet B to A (imperial and metric)
Imperial
Straight Segment
Curved Segment
T = T0 + fws
T0
w
f
T0 /(wr) =
fq =
h
s
T
q
f
RUB
T0
PTR(wr) =
w
r
BTR
PTR
w
r
T
200
7.6
0.31 100
0
436
0.31
40
12.4
436
7.6
60
.96
1.53
7.6
60
698
698
7.6
0.31 150
0
1052
0.31
30
9.3
1052
7.6
40
3.46
5.38
7.6
40
1636
1636
7.6
0.31 200
0
2107
Metric
Straight Segment
T0 = w [(fx) ± h] +
T0
w
f
x
Curved Segment
fq =
T
h
f
q
RUB
T0 /(wr) =
T0
w
PTR(wr) =
BTR
r
PTR
w
r
T
0.31 30.5
0
1940
0.31
40
12.4
1940
111
18
.97
1.53
111
18
3057
3057 111
0.31 45
0
4605
0.31
30
9.3
4605
111
12
3.46
5.38
111
12
7166
7166 111
0.31 61
0
9300
890 111
NOTE:
© 2007 BICSI®
Many manufacturers of pulling lubricants offer online or direct assistance in calculating expected pulling tensions. They also offer software programs.
5-47
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Designing Curved Conduit Sections
Curved section design allows conduit structure to be utilized effectively so that cable can be
pulled with the least amount of tension.
A curved section can be either a simple bend or an offset bend (i.e., a compound curve,
reverse curve, double curve, or S curve).
Because more tension is required to pull a cable through a curved section of duct than through
a straight section of equal length, the total length is generally reduced. The amount of
reduction depends on:
•
The number of bends.
•
The displacement angle and radius curvature of each bend.
•
Bend locations in the conduit section.
•
Type of conduit.
•
Amount and type of lubricant used.
In designing curved sections, the designer should consider:
•
Continuous lengths of straight individual plastic conduit can be formed into shallow curves
if a curvature radius of 12 m (40 ft) or more is used.
•
Where the radius is less than 12 m (40 ft), 4.6 m (15 ft), radius manufactured bends must
be used. If possible, the entire change in direction should be made with a single arc of
4.6 m (15 ft) radius.
•
If using an individual conduit with a curvature radius of less than 24 m (80 ft), the duct
must be encased in concrete. The encasement at a minimum should result in 51 mm (2 in)
of top cover, 25 mm (1 in) at the sides and beneath the structure.
•
The arcs in an offset bend should be symmetrical.
Air-Assisted Cable Installation
An alternative to installing optical fiber cable, some coaxial cables, and some smaller diameter
multipair twisted-pair cables in underground structures, is by pulling it with a winch line or
using cable blowing equipment.
Blowing cable differs from traditional cable pulling in many ways. During cable pulling, the
cable remains taut and under stress with pulling force applied to the cable end. The cable
tends to travel in a straight line unless a bend or curve in the duct alters its path. The cable
rubs on the duct at each bend, curve, or undulation, creating friction that can damage the cable
sheathing or the duct. As friction increases, additional cable-pulling force must be applied to
keep the cable moving. With additional pulling force, the stress on the cable increases (see
Table 5.8).
OSP Design Reference Manual, 4th edition
5-48
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Air-Assisted Cable Installation, continued
Cable placement by cable blowing or jetting has advantages of reduced tensile force required
for pulling, fewer personnel, and longer cable run lengths between access points (APs). Air
flow through the duct is used to overcome the frictional resistance of cable movement. Cable
movement speed is significantly faster with blowing rather than traditional pulling. Cable
blowing minimizes the stress on the cable during installation.
Depending on characteristics of duct, cable, and ambient temperature, installations of about
2.0 kilometers (km [1.2 miles (mi)]) are the most common. Cable blowing is one of the most
efficient and safest means of installing optical fiber cable, some types of coaxial cable, and
some types and arrangements of twisted-pair cable. Smooth wall or longitudinal ribbed are
acceptable, with smooth wall considered the best choice. Duct and couplings must be capable
of withstanding the air pressure present during blowing operations.
Innerduct joints are joined by a coupler by rotation, fusion (gluing), or pressure coupling.
Pressure testing devices can measure whether the joint can withstand a pressure of more
than 1032 kilopascals (kPa [150 pounds per square inch (psi)]) once joined. The test involves
plugging one end and applying pressure through the pipe, then measuring the loss in
kPa pounds per square inch (psi) during a time interval following pressurization.
© 2007 BICSI®
5-49
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Microduct
A microduct system houses dedicated channels enclosed in a protected jacket, which is
designed for installation in indoor and outdoor environments (see Figure 5.9.) Microduct
systems can be installed into empty or occupied duct structures via jetting, blowing, or pulling
installation methods. With this infrastructure in place, very small optical fiber cables
(i.e., microcables) can be installed inside the microduct by the same methods. Small units are
used to blow up to 900 m (3000) ft of optical fibers in place into microducts.
Advantages of microduct include:
•
Rapid deployment of optical fiber once the initial micro tube infrastructure is in place.
•
Reduced labor costs.
•
Minimized splicing and closure costs.
•
Easy moving, rerouting, or replacing of optical fibers upon installation.
•
Improved restoration time.
Disadvantages of microduct include:
•
High initial cost.
•
Difficult administration.
•
Manufacturer-specific products.
Figure 5.9
Microduct
OSP Design Reference Manual, 4th edition
5-50
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Calculating Volume of Backfill
The volume of concrete or granular backfill varies with trench width and the degree of
irregularity of the trench surface. Volumes given for each arrangement are for the minimum
trench width consistent with the specified clearances. Volumes for sand or granular backfill
should include an allowance for compaction. Concrete encasement will be required at bends
using PVC conduit or where surface loads are in excess (see Figures 5.10 and 5.11 and the
corresponding tables 5.10 and 5.11).
Figure 5.10
Typical concrete-encased conduit structure
Ground line
Warning tape
610 mm
(24 in) min*
51 mm (2 in)
Top level
of concrete
25 mm (1 in)
38 mm (1.5 in)
25 mm (1 in)
38 mm (1.5 in)
* 457 mm (18 in) permitted under
driveways and sidewalks
in =
mm =
Inch
Millimeter
Table 5.10
Cubic yards of concrete per 30.5 m (100 ft) of trench
Trade
Size 4
2 Conduit
Wide
3 Conduit
Wide
4 Conduit
Wide
2 conduit high
2.7
3.7
4.8
3 conduit high
3.7
5.0
6.4
4 conduit high
4.6
6.4
8.1
NOTE:
© 2007 BICSI®
To convert from cubic yards to cubic meters, multiply by 0.76.
5-51
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Calculating Volume of Backfill, continued
Figure 5.11
Typical compacted fill conduit structure
Selected material
free of large stones,
frozen material, etc.
Ground line
Warning tape
305 mm
(12 in) min*
Compacted
sand or
granular
backfill
305 m (12 in)
25 mm (1 in)
25 mm (1 in)
51 mm
(2 in)
25 mm
(1 in)
25 mm (1 in) Typical
* 152 mm (6 in) permitted under
driveways and sidewalks
in =
m =
mm =
Inch
Meter
Millimeter
Table 5.11
Cubic yards of compacted fill per 30.5 m (100 ft) of trench
Trade
Size 4
2 Conduit
Wide
3 Conduit
Wide
4 Conduit
Wide
2 conduit high
6.4
8.7
11.0
3 conduit high
7.4
10.1
12.8
4 conduit high
8.5
11.6
14.5
NOTE:
To convert from cubic yards to cubic meters, multiply by 0.76.
OSP Design Reference Manual, 4th edition
5-52
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Trench Work
For all excavations deeper than 1.52 m (5 ft) in which a person must enter or work, in the
United States, for example, the Occupational Safety and Health Administration (OSHA)
requires the walls be shored, sheeted, braced, or otherwise supported except when:
•
Working in solid rock, hard shale, or hard slag.
•
The side walls are cut to an approved slope.
Requirements may vary with soil type and location. The designer should consult OSHA and
local regulations. Other safety precautions include:
•
Shoring trenches less than 1.52 m (5 ft) deep if they present a hazardous work
environment.
•
Assigning an individual at the surface of an excavation to monitor persons working in the
trench.
NOTE:
The person must be in sight of the monitor at all times.
Prefabricated trench boxes or shields have become lighter and are available in a variety of
materials. Manufacturer specifications will vary and must be qualified for design purposes.
Typical shoring arrangements are shown in Figures 5.12, 5.13, and 5.14; see also Table 5.12.
Figure 5.12
Typical trench shield
Loose soil
Steel sidewall
Cross brace
NOTE:
© 2007 BICSI®
If depths are greater than 6 m (20 ft), it is recommended that shoring construction
should be designed by a qualified professional engineer.
5-53
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Trench Work, continued
Figure 5.13
Typical trench with shoring in unstable ground
101 mm x 152 mm
(4 in x 6 in)
cross brace
(or trench jack)
1.83 m
(6 ft)
51 mm x 152 mm
(2 in x 6 in) tight
spaced uprights
Loose soil
1.2 m
(4 ft)
101 mm x 152 mm
(4 in x 6 in)
stringer
Trench depth
3 m (10 ft)
or less
(See NOTE)
Sharpen toe
of uprights
ft
in
m
mm
=
=
=
=
Trench width
1.83 m (6 ft)
or less
Sharpen toe
of uprights
Foot
Inch
Meter
Millimeter
NOTE:
Leave 101 mm (4 in) to 152 mm (6 in) working space between brace and conduit.
OSP Design Reference Manual, 4th edition
5-54
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Trench Work, continued
Figure 5.14
Typical trench with shoring in stable ground
51 mm x 152 mm
(2 in x 6 in) upright
1.8 m
(6.0 ft)
101 mm x 101 mm
(4 in x 4 in)
cross brace
(or trench jack)
51 mm x 152 mm
(2 in x 6 in) upright
1.2 m
(4 ft)
Hard, compact soil
101 mm x 101 mm
(4 in x 4 in)
cross brace
(or trench jack)
Trench depth
3 m (10 ft)
or less
(See NOTE)
Cleat
Trench width
1.83 m (6.0 ft)
or less
ft
in
m
mm
=
=
=
=
Foot
Inch
Meter
Millimeter
NOTE:
© 2007 BICSI®
Sharpen toe
of uprights
Leave 101 mm (4 in) to 152 mm (6 in) working space between brace and conduit.
5-55
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Trench Work, continued
Table 5.12
Minimum trench shoring requirements
Trench Depth
(m/ft)
Soil
(Note 1)
Size
(Note 5)
1.52–3 (5–10)
A
B
3 × 4 or 2 × 6
C
3–4.6 (10–15)
Spacing
m/ft
Stringers
1.83 m
2.74 m
3.7 m
4.6 m
(Notes 2&5)
(6 ft)
(9 ft)
(12 ft)
(15 ft)
1.83 (6)
None
0.91 (3)
4×6
Tight
4×6
D
Tight
6×8
A
1.2 (4)
4×6
0.6 (2)
4×6
Tight
4×6
B
3 × 4 or 2 × 6
C
4.6–6 (15–20)
Cross Braces for Trench
Width
(Notes 3, 4, and 5)
Uprights
D
3×6
Tight
8 × 10
All
3×6
Tight
4 × 12
4×4
4×6
6×6
6×8
4×6
6×6
6×8
8×8
4×6
6×6
6×8
8×8
6×6
6×8
8×8
8 × 10
6×8
8×8
8 × 10
10 × 10
ft = Foot
m = Meter
NOTES: 1. Soil type or conditions: A is hard, compact
B is likely to crack
C is soft, sandy, or filled
D is hydrostatic pressure
2. Stringer vertical spacing is 1.2 m (4 ft)
3. Cross braces spaced 1.2 m (4 ft) vertically, 1.83 m (6 ft) horizontally.
4. Trench jacks may be used in lieu of, or in combination with, cross braces.
5. Size refers to construction grade lumber in inches.
OSP Design Reference Manual, 4th edition
5-56
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Trench Work, continued
Subsurface Space
The amount of subsurface space required for the conduit structure is dependent on the type,
size, and number of ducts to be installed.
Where sheeting or shoring is not required, the amount of required subsurface space is based
on the width of the conduit formation plus the space needed for:
•
Working.
•
Backfill.
•
Concrete encasing.
The depth of the trench is the height of the conduit formation plus 610 mm (24 in) of cover
and any top protection or bedding requirement. The NESC requires 610 mm (24 in); however,
local requirements may differ.
NOTE:
Where shoring or plywood sheeting is required, the width must include the dimensions of the material used.
Conduit Design for Bridge Crossing
Whenever conduit must cross a bridge, the designer should always consult the AHJ and a
structural and/or civil engineer regarding:
•
Structural strength problems, if the ducts will be incorporated in the bridge structure.
•
Obstruction of waterways, if the ducts will be attached under the bridge.
•
Compensation for axial movement at each required expansion joint.
•
Slip sleeve requirements at a bridge abutment (see Figure 5.15) or an MH wall, if the MH
is close to the bridge.
Figure 5.15
Bell end conduit slip sleeve
Bridge structure
Bridge abutment
© 2007 BICSI®
5-57
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Conduit Design for Bridge Crossing, continued
When conduit crosses a bridge, MHs built as termination points should be constructed close to
the bridge ends in the approach fill. If due to bridge length this results in an excessively long
section, pull boxes or specially designed splicing chambers of sufficient size may be placed to
aid cable pulling and splicing along the span. Refer to Figures 5.16 through 5.25.
Conduit supports are modular-type hangers designed to support and maintain the integrity of
conduit systems on bridge crossings.
Each bridge crossing must be individually designed to conform to local conditions and
restraints imposed by the bridge site, design, and construction.
In the design phase, the designer should consult the AHJ to obtain R/W and design information
on load limits and expansion requirements.
During temperature changes, exposed plastic conduit will change length in proportion to the
magnitude of the temperature change. The conduit system must be designed so that length
changes can take place without disengaging at the expansion coupling or developing excessive
stresses or deflections.
Bridge conduit support hardware manufacturers provide the required data to properly design
and install their product.
Under Bridge Hanger/Conduit Method
To provide secure support of the conduit system, conduit hangers are located at specific
intervals along the structure. They should be spaced at 2.4 m (8 ft) intervals for PVC Type D
conduit and at 1.8 m (6 ft) intervals above 32° Celsius (C [90° Fahrenheit (F)]).
Because of the inherent thermal expansion and contraction of the conduit materials, expansion
joints (see Figure 5.16) must be provided for each 30.5 m (100 ft) of PVC Type D conduit.
Figure 5.16
Expansion joints
27.4 m
(90 ft)
30.5 m
(100 ft)
30.5 m
(100 ft)
30.5 m
(100 ft)
30.5 m
(100 ft)
27.4 m
(90 ft)
Abutment
= Anchor point support with stop ring
= Back-to-back expansion joint
ft = Foot
m = Meter
NOTE:
An expansion joint is not placed at bridge abutment due to possible misalignment.
OSP Design Reference Manual, 4th edition
5-58
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Conduit Design for Bridge Crossing, continued
There are two general types of bracing:
•
Angle bracing (Figure 5.17).
•
Longitudinal bracing (Figure 5.18).
Angle bracing enables supports to resist the forces developed from expansion and contraction,
cable pulling, and longitudinal stranding. Angle bracing is required on both sides of all anchor
point supports.
Figure 5.17
Angle bracing
Anchor point
hanger
Strut bolted to
threaded insert
in bridge deck
51 mm (2 in) x 51 mm (2 in)
frame member
in = Inch
mm = Millimeter
© 2007 BICSI®
5-59
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Conduit Design for Bridge Crossing, continued
Intermediate conduit supports experience primarily three different loadings:
•
Loads in vertical direction, from the weight of the conduit, cable, and hangers
•
Loads in transverse direction, imposed by wind
•
Loads in longitudinal direction, imposed by the frictional force developed by the expansion
and contraction of the conduit
Intermediate hangers transfer these forces at two points:
•
Attachment bolts
•
Longitudinal bracing
Figure 5.18
Longitudinal bracing and load forces
Direction of
conduit run
Support
Vertical
direction
Weight of
conduit
Transverse load or
normal direction of wind
Longitudinal
bracing
Longitudinal direction
Direction of expansion
frictional force
Direction of load
on stranding
Anchor points experience the same loading as intermediate-type supports except forces due to
friction. Anchor points must also withstand cable pulling force and longitudinal strand loads.
The total longitudinal stranding load will be the summation of the intermediate loads on the
strand. See Figure 5.19 for anchor and plug.
OSP Design Reference Manual, 4th edition
5-60
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Conduit Design for Bridge Crossing, continued
Figure 5.19
Anchor and plug
Expander plug
Anchor
Back-to-back expansion joint units:
•
Are located at anchor point hangers.
•
Control expansion and contraction of the conduit run 30.5 m (100 ft) in each direction
(see Figures 5.20 and 5.21).
Figure 5.20
Back-to-back expansion joint units
30.5 m (100 ft) 30.5 m (100 ft)
Anchor-type
support
30.5 m (100 ft)
30.5 m (100 ft)
ft = Foot
m = Meter
Expansion
joint
Intermediatetype support
Stop-ring
restraint
point
© 2007 BICSI®
5-61
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Conduit Design for Bridge Crossing, continued
Figure 5.21
Back-to-back expansion joint
Approximately
30.5 m (100 ft)
Approximately
30.5 m (100 ft)
Approximately
30.5 m (100 ft)
Anchor point
Nipple
ft =
m =
Expansion
joint sleeve
Split stop ring
Foot
Meter
In some cases, spans of 91 m (300 ft), 152 m (500 ft), and 213 m (700 ft) require combining
the back-to-back system with one in-line single expansion joint assembly (see Figure 5.22).
Figure 5.22
In-line single-expansion joint over 30.5 m (100 ft)
30.5 m (100 ft)
ft =
m =
30.5 m (100 ft)
30.5 m (100 ft)
Foot
Meter
OSP Design Reference Manual, 4th edition
5-62
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Conduit Design for Bridge Crossing, continued
In short crossings, under 30.5 m (100 ft), only one expansion joint is required (see
Figure 5.23). The expansion joint should be located near the center of the bridge
between supports.
Figure 5.23
Expansion joint under 30.5 m (100 ft)
30.5 m (100 ft)
ft =
m =
Foot
Meter
In installations under 30.5 m (100 ft), normally only one expansion joint is required for each
conduit line. It can be installed near the center of the bridge in between two supports (see
Figure 5.24).
Figure 5.24
Single expansion joint
Cement
Nipple
Conduit
Support
© 2007 BICSI®
Single-action
expansion
joint sleeve
5-63
Cement
Second
support
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Conduit Design for Bridge Crossing, continued
When using longitudinal stranding, angle bracing should be angled into the stranded area.
Figure 5.25 shows the concept and a designed system without the conduit.
Figure 5.25
Angle bracing into stranded area
Back-to-back
expansion joints
30.5 m (100 ft)
Longitudinal
bracing with
wire strand
ft =
m =
Foot
Meter
OSP Design Reference Manual, 4th edition
5-64
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Conduit Design for Bridge Crossing, continued
Many other methods of bridge crossing exist; some are shown in Figures 5.26 through 5.29.
Figure 5.26
Conduit installed in sidewalk portion of bridge
Sidewalk
Roadway
Figure 5.27
Conduit installed by hanging under sidewalk portion of bridge
Sidewalk
© 2007 BICSI®
Roadway
5-65
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Conduit Design for Bridge Crossing, continued
Figure 5.28
Conduit run attached to side of bridge with steel brackets
Steel brackets
Figure 5.29
Conduit runs attached to steel I-beams
I-Beam
OSP Design Reference Manual, 4th edition
5-66
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Tunnels
Introduction
New or existing tunnels may be the only means available to provide service into or throughout
a building. Three general types of tunnels are:
•
Utility tunnels.
•
Pedestrian tunnels.
•
Vehicular tunnels.
Utility Tunnels
Utility tunnels are spaces/pathways that house various utilities. Some of the utilities housed
are steam, power, gas, water, sanitary sewer, and telecommunications. Designing space
configurations for these tunnels is of prime concern for the designer. Power cables located in
tunnels can produce electromagnetic interference (EMI). Gas lines can produce a hazardous
atmosphere. Steam lines can damage the telecommunications plant if it is located too close
to the steam lines. Water lines may create a humid atmosphere along with the steam lines.
Sanitary sewer lines can create a biological hazard if ruptured. Storm drains that feed into the
tunnels can cause flooding. See Figure 5.30 for a breakdown of a typical shallow tunnel.
© 2007 BICSI®
5-67
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Utility Tunnels, continued
Figure 5.30
Typical shallow tunnel section
3.4 m
(11 ft)
Monorail
Steam
Telephone
1.2 m
(4 ft)
3.4 m
(11 ft)
Low voltage
power
High voltage
power
Water
Gas
ft = Foot
m = Meter
OSP Design Reference Manual, 4th edition
5-68
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Pedestrian Tunnels
Pedestrian tunnels are used for passage of personnel from one part of a campus to another,
usually under streets, railways, or other thoroughfares. These tunnels are usually environmentally conditioned and contain spaces that can efficiently house pathways for information
transport systems (ITS). They tend to be shorter than utility tunnels but can be used
effectively for housing of telecommunications infrastructure from one point on a campus to
another.
Vehicular Tunnels
Vehicular tunnels allow restricted traffic. These tunnels are used for passage of vehicles from
one part of a campus to another and are not typically environmentally controlled. Pathways
can be installed inside these tunnels to house telecommunications cables in a cost-effective
manner.
Telecommunications cable must be installed in these tunnels according to local codes and must
also provide a safe environment for operation of all facilities. For large projects, tunnels will
require extensive advanced planning and cooperation among:
•
Utilities.
•
Customers.
•
Municipal planning boards.
•
Environmental groups.
•
Department of Transportation (DoT).
All of these entities must be in agreement regarding tunnel use and design and the designs of
the proposed utility installations within the tunnel.
Considerations that are particularly critical include:
•
Routing.
•
Safety.
•
Access.
•
Capacity.
•
Sizing.
•
Facility protection.
•
R/W.
•
Cost.
Accessibility is usually the reason for installation of tunnels. When designing the tunnel, the AP
should be located off the traveled roadway to improve worker’s safety.
When the public accesses a tunnel or when the customer’s personnel must enter the structure
to install, operate, or maintain the facilities, the design must include a controlled, safe
environment including barriers, detectors, alarms, ventilation, and pumps.
© 2007 BICSI®
5-69
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Motivating Design Factors
The motivating design factors for considering the use of existing utility tunnels are:
•
Increasing congestion of belowground space.
•
Rate of growth.
•
Removing obsolete plant after placing a new plant.
•
Environmental awareness.
•
Cost analysis and utilization of facilities.
Application Areas
Five areas where tunnels may provide an optimum long-range solution to a customer’s space
requirements are:
•
Transit subway station construction.
•
Urban renewal districts.
•
Central business districts.
•
Campus or institutional projects.
•
Large-capacity pathways under known underground obstructions (e.g., buildings).
Advantages
Primary advantages of using a tunnel include:
•
Reduced street maintenance.
•
Decreased chances of accidental dig-ups.
•
Reduced ground corrosion factors.
•
A continuous inspection path for all facilities.
•
Permanent space allocation.
•
Reduced surface interference to both vehicular and pedestrian traffic, except during an
open-cut phase.
Disadvantages
Disadvantages of using a tunnel may include:
•
Confined space rules.
•
Significant planning and approvals from all aspects.
•
Increased liability and work priority factors.
•
Increased security measures.
•
High initial cost of constructing the tunnel.
OSP Design Reference Manual, 4th edition
5-70
© 2007 BICSI®
Section 1: Underground Pathways
Chapter 5: Pathways and Spaces
Utility Requirements
A joint-use tunnel may require sizing for:
•
Heating and cooling.
•
Electric power.
•
Gas.
•
Sanitary sewers.
•
Telecommunications.
•
Water.
•
CATV.
•
Storm water runoff monitoring.
When either sizing tunnels or placing telecommunications facilities in tunnels, allowances
should be made for regulated, nonregulated, and multiple transmission media (e.g., balanced
twisted-pair, optical fiber, coaxial cabling). Each individual utility should be marked at regular
intervals for easy identification.
When selecting media for installation, the designer should ensure that it meets heat and steam
requirements to ensure protection of the telecommunications physical plant, where necessary.
Hazards
Major hazards found in tunnels are:
•
Confined space.
•
Steam.
•
Flooding.
•
Gas.
•
Fire.
•
Electricity.
•
Asbestos.
•
Sanitary sewer lines.
•
Storm drains.
•
Wildlife.
While various sensors and alarms can be used to monitor the environmental quality of a tunnel,
OSP installers should always observe caution and report any suspicious conditions to the
appropriate safety office or the director of physical plant immediately.
© 2007 BICSI®
5-71
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 1: Underground Pathways
Ventilation
A common rule of thumb for personnel ventilation is three complete air changes per hour.
Tunnels may contain combustible or suffocating gasses. Therefore, provisions must be made
for an adequate continuous supply of air.
Fire Detection
Types of fire detection systems used in tunnels are:
•
Infrared.
•
Ultraviolet.
•
Temperature.
•
Detectors for products of combustion (i.e., smoke or carbon dioxide).
Support Structures
Additional support structures may be needed for telecommunications. The designer should
consult with AHJs for installations. Some examples are:
•
Pulling eyes—Generally made of steel and concreted into the sides or ends of the tunnel
to facilitate the pulling of cable into or through the tunnel. Pulling eyes should be placed at
about the same level as the ductbank at the opposite end of the tunnel.
•
Cable and equipment supports—Vertical steel channels should be installed to support
cables, splice cases, and equipment.
OSP Design Reference Manual, 4th edition
5-72
© 2007 BICSI®
Section 2: Direct-Buried Pathways
Chapter 5: Pathways and Spaces
Direct-Buried Pathways
Introduction
The decision of whether to place direct-buried or aerial plant is based on:
•
Initial cost.
•
Susceptibility to damage.
•
Ongoing maintenance costs.
•
Aesthetics (i.e., direct-buried cable installations are generally hidden from view).
Direct-buried cable is less susceptible to storm damage than aerial cable. Even though repair
costs may be higher, these structures are less frequently damaged, especially in areas prone to
fires or severe weather (e.g., ice storms, hurricanes).
Route Selection
When considering an underground or direct-buried route, many variables must be considered,
some of which may be related. Common variables are:
•
Safety.
•
Costs.
•
Waterways.
•
Environmental areas.
•
Soil conditions.
•
Right-of-way (R/W).
•
Obstacles.
•
Other below-grade utilities.
•
Existing infrastructure.
Both underground and direct-buried pathways may be affected by:
© 2007 BICSI®
•
Buildings.
•
Culverts.
•
Bridges.
•
Pole lines.
•
Pavement.
•
Landscaped areas.
•
Railways.
•
Roadways.
5-73
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 2: Direct-Buried Pathways
Route Selection, continued
When crossing another utility facility, always remember:
•
Maintain 305 millimeters (mm [12 inches (in)]) of separation. Placing cable in this manner
adds further protection against dig-ups.
•
Cabling systems should be routed to allow safe access for construction, inspection, and
maintenance.
•
There shall be no transfer of load (i.e., weight) from one utility to the other.
•
When crossing roads, railroads, and waterways, the cable should be placed inside either a
metal or rigid plastic duct for protection.
Soil conditions play a major role in route selection. Areas of rock or unstable soil should be
avoided, if possible. If it is not practical to avoid areas of rock, consideration should be given
to decreasing the depth of placement and then mechanically protecting the cable by using
cable shields (see Figure 5.31). These shields can be either metallic or nonmetallic and may be
field constructed using split duct, short conduit sections, or U-guards.
Figure 5.31
Protection of direct-buried cable
Minimum
required
depth
Ground
level
Less than minimum
required depth
Buried cable
Shield
Rock
Direct-buried cable
OSP Design Reference Manual, 4th edition
5-74
© 2007 BICSI®
Section 2: Direct-Buried Pathways
Chapter 5: Pathways and Spaces
Plow Route Selection
When selecting a plow route, the designer must remember that:
•
An acceptable route must be wide enough to accommodate a plowing tractor.
•
Cable reels are typically mounted above and in front of the tractor. The route must have
sufficient vertical clearance to permit safe and proper operation of equipment.
When selecting a bore route, the designer should consider:
•
Number of bores it will take to accomplish the crossing. For example, when crossing a
multilane highway, an additional pit may have to be set up in the median, requiring two
bores instead of one.
•
Space needed for a boring and receiving pit. The size of the equipment being used and the
rod lengths must be known before making this decision.
•
Costs of surface cuts and restoration.
Burial Depth
Burial depth will be affected by:
•
Crossing under railroads and highways.
•
Crossing bodies of water.
•
Crossing other utilities.
•
Frost line depth. Cable should be placed below the frost line because frost uplift may
damage cables. Optical fiber cables may be crushed by freezing water. Where applicable,
the 50-year frost line should be used.
•
End user requirements.
Each of the above situations may require adherence to specific requirements mandated by
their governing agencies. If joint trenching is being used, agreements with other occupants
must be obtained.
Balanced twisted-pair cable should be placed at a minimum depth of 610 mm (24 in).
However, in areas where future excavation is anticipated, it may be advisable to place the
cable at a greater depth. For example, if road grading that will remove 610 mm (24 in) of dirt
is planned in a particular area, it would be wiser to place the cable at 1.2 meters (m [4 feet
(ft)]) initially versus the standard 610 mm (24 in). The designer should also remember that
depth requirements may vary by local code.
Optical fiber cable should be placed at a minimum depth of 1 m (3.28 ft). However, extra
depth should be considered in situations where future potential excavations could damage the
cable.
These depths may be reduced if the cable is adequately protected by additional means
(e.g., concrete encasement or capping). The authority having jurisdiction (AHJ) may provide
rulings on depth in a given area.
© 2007 BICSI®
5-75
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 2: Direct-Buried Pathways
Burial Depth, continued
Bore sites play an important role in selecting bore depth. Different depth requirements will
exist when boring under:
•
Sidewalks.
•
Streets and highways.
•
Railroads.
•
Waterways.
•
Environmentally sensitive areas.
In any of these cases, the AHJ sets the minimum boring depth.
OSP Design Reference Manual, 4th edition
5-76
© 2007 BICSI®
Section 2: Direct-Buried Pathways
Chapter 5: Pathways and Spaces
Placing Direct-Buried Cable
Trenching
Three basic methods of trenching are:
•
Hand dig, used when there is not enough room for machinery or when care must be
exercised to avoid an obstacle.
•
Back hoe, used in areas not accessible by a trencher.
•
Trencher, preferred when the proposed cable route is open and free from obstacles.
The smaller trenchers are walk-behind types and typically are used for small-diameter
cable applications and short distances (see Figure 5.32). Larger trenchers generally are
used for placing larger cables (see Figure 5.33).
Depending on the method employed, trench width can range from 76 to 610 millimeters (mm
[3 to 24 inches (in)]) and up to 2.3 meters (m [7.5 ft (feet)]) in depth.
Smaller cables may be placed using a less cumbersome machine, which can readily avoid
obstructions and can be controlled by an individual walking behind it. While such a machine
has limited use for long runs or large sizes of cable, it may be effective in placing smaller
lateral cables or service wires. Many configurations of cable placing machines are available.
The designer should focus on determining the best route rather than on the machinery for
cable placement.
Figure 5.32
Walk behind trencher
© 2007 BICSI®
5-77
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 2: Direct-Buried Pathways
Trenching, continued
Figure 5.33
Tractor-drawn trencher
Plowing
The most economical rates for plowing will be realized when the route is open and relatively
free from rock.
Two major types of plows are:
•
Vibratory plow.
•
Rip plow.
OSP Design Reference Manual, 4th edition
5-78
© 2007 BICSI®
Section 2: Direct-Buried Pathways
Chapter 5: Pathways and Spaces
Plowing, continued
Vibratory Plow
This type of plow slices open the trench, places cable, and closes the trench behind it. Some
machines possess both trenching and plowing capabilities (see Figures 5.34 and 5.35). The
major difference is that these types of machines are generally rubber-tired to minimize surface
damage. This limits their usefulness in some field conditions.
Figure 5.34
Trencher/vibratory plow
Figure 5.35
Vibratory plow
© 2007 BICSI®
5-79
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 2: Direct-Buried Pathways
Plowing, continued
Rip Plow
This type of plow opens a trench with one or more passes of the plow share (see
Figure 5.36). The rip plow ensures all subsurface obstacles are removed prior to
placing the cable. Use of this plow is common in hard ground conditions such as
clay in the summer months.
Figure 5.36
Rip plow
Rock Saw
When the soil is too compacted or rock is encountered, the rock saw is used to cut the trench
for the cable placement (see Figure 5.37).
Figure 5.37
Rock saw
OSP Design Reference Manual, 4th edition
5-80
© 2007 BICSI®
Section 2: Direct-Buried Pathways
Chapter 5: Pathways and Spaces
Plowing, continued
Clearances from Existing Utilities
Since plowing is not as accurate as mechanical trenching, use of hand digging will allow
enough space between the proposed trench and existing utilities to minimize the chance for
contact while plowing. It is not recommended to use any form of mechanical excavation
within 1 m (3.28 ft) of other utilities.
Boring
The three main types of bores are:
•
Auger bore, also known as jack and bore.
•
Horizontal directional drilling (HDD), also known as a directional bore.
•
Missile bore, also known as impact moling.
Auger Bore System
The auger boring system (i.e., jack and bore) uses an auger bit attached to the end of a boring
rod. The boring machine drills a hole with the first rod and auger. Once the machine has
reached the length of the rod, a second rod is added and the boring continues. As additional
length is needed, more rods are added until the auger reaches the receiving pit. This method
should only be used for short bores since it is not very accurate.
Any obstacle encountered during the bore can deflect the auger bit to a different path. It
is always wise to know the exact length of the bore. If the auger does not appear in the
receiving pit after the appropriate number of rods has been added to the machine, it has likely
taken a different route. A metal detector can be used to track the auger’s progress during the
bore.
© 2007 BICSI®
5-81
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 2: Direct-Buried Pathways
Boring, continued
A casing may be installed simultaneously with the boring process to make this a less costly
alternative to cutting and patching. It is used for crossing under small obstacles such as roads
or railroad tracks and can be used to place casings as large as 1.2 m (4 ft). Figure 5.38
illustrates an auger bore.
Figure 5.38
Auger bore
OSP Design Reference Manual, 4th edition
5-82
© 2007 BICSI®
Section 2: Direct-Buried Pathways
Chapter 5: Pathways and Spaces
Boring, continued
Horizontal Directional Drilling (HDD)
HDD is a much more accurate method of boring (see Figure 5.39). This system uses a liquid
chemical mixture that, when forced through the end of the boring head, carves a hole in the
earth. However, unlike a slurry mixture that merely washes away the dirt, this mixture
hardens and forms a crust after the hole carving. The boring head is controllable in all planes
by the operator. Most machines carry enough pipes on board to complete a bore well beyond
100 m (328 ft). Based on the locator’s instructions, the operator adjusts the boring path head
to ensure its arrival at the receiving pit.
The boring rig typically consists of a track-based boring machine, a cable locator and a
separate trailer or truck to hold the mixing tanks for the boring fluid.
A boring head detector traces the path of the head during the boring operation. This type
of construction can be used in many types of soil conditions, and can create a path up to
2 kilometers (km [1.2 miles (mi)]) long and 1.2 m (4 ft) diameter. It allows for placement
of multiple ducts or direct placement of facilities in the path and enables crossing obstacles
(e.g., rivers, utility clusters).
Figure 5.39
Horizontal directional drilling machine
© 2007 BICSI®
5-83
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 2: Direct-Buried Pathways
Boring, continued
Missile Bore System
The missile bore system, also known as impact moling, is used for short run cable installations
under sidewalks, driveways, roads, and other obstacles. With these units, a pipe can be pulled
or pushed under an obstacle by repetitive impacts. The force may be applied by pneumatic or
hydraulic methods. Typically, bores from 51 to 152 mm (2 to 6 in) in diameter can be made
with this method.
Pits are dug at the beginning of the (launch) pit as well as at the receiving end, generally
7.6 to 15 m (25 to 50 ft) apart, and the missile is directed forward by a series of pneumatic
blasts until it reaches the target pit. The pipe or casing is carried forward with the drill head.
This method is not accurate because it has no steering capabilities, so it is limited to short
distances only.
Casing Type
Depending on the customer’s or authority having jurisdiction (AHJ) requirements, one of the
following casings may be used:
•
Steel
•
Plastic
•
Flexpipe
Cable Markers
Buried cable markers should be used to reduce the possibility of cable damage during
excavation and will assist in the location of dielectric optical fiber cable.
Some types of common markers are:
•
Aboveground post markers, typically placed up to 152 m (500 ft), at a directional change,
at a congested area, or at a location of importance (e.g., other major crossing utilities).
In areas where curves or hills exist, markers should be placed in line of sight (LoS).
•
Buried marker tape 152 to 305 mm (6 to 12 in) below final grade.
•
Buried electronic markers, typically located at splice locations and buried
handholes (HHs).
NOTES: Tracer wire should be installed with all dielectric optical fiber cable to
facilitate locating.
Cable markers with locating caps that allow locators to connect to the metallic
sheath of a buried cable may be used within a maximum distance of
900 m (3000 ft).
OSP Design Reference Manual, 4th edition
5-84
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Aerial Pathways
Introduction
When faced with design and implementation of an aerial plant system, the designer must
consider:
•
Initial cost.
•
Possible exposure of poles to damage from vehicular traffic.
•
Risk of damage to conductors or pole structures from falling tree limbs, high winds, ice
loading, and other environmental factors.
•
Access.
Route Selection
When selecting the route for the aerial plant, the designer must consider a number of
variables, including:
•
Safety.
•
Terrain.
•
Aesthetics.
•
Direct-buried or underground utilities.
•
Soil conditions.
•
Other aerial plants.
•
Access.
A proposed pathway may be affected by obstacles and/or clearances due to:
© 2007 BICSI®
•
Utilities.
•
Existing pole lines.
•
Parking lots.
•
Buildings, including architectural impediments to locating building attachment structures.
•
Water crossings.
•
Intersections (e.g., street, alley, controlled access roads).
•
Driveways.
•
Right-of-way (R/W) for railways.
•
Maintenance access to the pole line.
•
Swimming pools.
•
Environmental areas.
•
Tree branches.
•
Clearances above sidewalks.
•
Clearances above or to the side of buildings and other structures.
•
Airport and heliopad.
5-85
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Route Selection, continued
Aerial construction or a combination of aerial and direct-buried construction may be less
expensive in heavily developed or rocky areas. Aerial construction may also reduce costs
when a preexisting pole line (partial or complete) can be used.
Designing New Aerial Support Structures
When determining design for aerial plant, consider the:
•
Weight of cable—Maximum span allowed for cable and future cables with appropriate
strand.
•
Height of poles—Determined by spacing requirements from other utilities, ground
clearances, roads, rail, and water crossings.
Grades of Pole and Pole Line Construction
Poles and pole lines that support outside plant (OSP) telecommunications cabling are classified
by grades or types based on the following criteria:
•
Importance of the services they offer
•
Physical size (i.e., length and circumference)
•
Loading capabilities
•
Pole strength (i.e., rated fiber stress and pole circumference)
Poles and pole lines associated with crossing limited access highways, railroads, and other
special situations shall comply with applicable codes, standards, and regulations.
Reuse of Existing Poles and Pole Lines
Where possible, the designer may want to use an existing pole line. Presence of the pole line
should be field verified and the poles along the proposed route should be physically examined
to ensure their physical integrity. The designer should not rely on records alone when planning
to use existing structures. When proposing placement of aerial cable on an existing joint use
pole line, it is mandatory to obtain authorization from the pole owner.
Owners of the existing pole line may require that makeready work be performed for a nominal
fee to allow for adequate clearances. This work may involve moving attachments on an
existing pole or placing a new pole and respacing attachments.
For transitions from subsurface to aerial construction, facility ownership may be determined
based on pole placement and pole markings. For new pole installation the designer will work
with the authority having jurisdiction (AHJ) to obtain a permit to place the pole and will call
the one-call system to locate subsurface utilities.
OSP Design Reference Manual, 4th edition
5-86
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Types of Loading
Three types of loading with which the designer should be concerned are:
© 2007 BICSI®
•
Transverse storm loading—The pressure exerted on a pole and its attachments by the
wind at a right angle to the line. The pressure on the pole varies with the length and
diameter of the pole.
•
Vertical loading—The weight of the attachments as well as the downward force produced
by the guys. For medium and heavy storm loading areas, the weight of ice coatings on
attachments should be included.
•
Bending moments—The forces produced by devices like (eccentric) transformers or
unbalanced tensions at corners and deadends.
5-87
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Storm Load Requirements
Codes, standards, and regulations determine a pole line’s storm loading requirements.
Following requirements are associated with storm loading:
•
Severity
•
Frequency
•
Damaging effects of wind and ice storms
Requirements associated with storm loading reflect the force exerted on overhead pole lines
by the combination of wind, ice, and snow. Light loading applies to areas receiving little or no
ice and snow accumulation, whereas medium loading and heavy loading apply to areas where
annual ice and snow accumulations are greater.
NOTE:
Codes like the National Electrical Safety Code® (NESC®) define wind and ice
loading for the continental United States (see Figure 5.40 courtesy of the Institute
of Electrical and Electronic Engineers, Inc.® [IEEE®]). Please refer to applicable
codes, standards, and regulations in your geographic area to determine if such
definitions and guidance are provided.
Figure 5.40
Wind and ice loadings
= Heavy
= Medium
= Light
OSP Design Reference Manual, 4th edition
5-88
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Storm Load Requirements, continued
Combined Ice and Wind Loading
The three degrees of loading due to weather conditions require treatment in calculating the
effects of the loads on the structure. Ice loading is not considered a factor in the light load
areas, but is included when addressing medium and heavy load areas. Wind loading is a factor
everywhere.
Light Loading
Light loading is a horizontal wind pressure of 43.9 kilograms per square meter (kg/m2
[9 pounds per square feet (lb/ft2)]) upon the projected area of supported wires, support
strands, and cables at a right angle to the line. Light loading applies to areas receiving little
or no ice and snow accumulation.
Medium Loading
Medium loading is a horizontal wind pressure of 19.5 kg/m2 (4 lb/ft2) upon the projected
area of supported wires, support strands, and cables when coated with a radial thickness
of 6.3 millimeters (mm [0.25 inches (in)]) of ice at a right angle to the line. Medium loading
applies to areas receiving moderate amounts of ice and snow accumulation.
Heavy Loading
Heavy loading is a horizontal wind pressure of 19.5 kg/m2 (4 lb/ft2) upon the projected
area of supported wires, support strands, and cables when coated with a radial thickness of
12.7 mm (0.50 in) of ice at a right angle to the line. Heavy loading applies to areas where
annual ice and snow accumulation is great.
Storm-loading districts are shown in Table 5.13. Any storm-loading district may have areas
where heavier or lighter loadings than are indicated for that district prevail. In those areas, the
designer must alter the requirements set up for the loading district to comply with local
conditions. The conditions must not be reduced without written approval from the AHJ.
Storm-loading districts should be determined through coordination with the local meteorological
service for that country.
© 2007 BICSI®
5-89
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Storm Load Requirements, continued
Table 5.13
Ice, wind, and temperature
Loading Districts
Heavy
Medium
Light
Extreme
Wind Loading
12.5 (0.50)
6.3 (0.25)
0 (0)
0 (0)
Horizontal wind
pressure in Pa (lb/ft2)
190 (4)
190 (4)
430 (9)
Temperature
in C (F)
–20 (0)
–10 (15)
–1 (30)
Radial thickness of
ice in mm (in)
C
F
in
lb/ft2
mm
Pa
=
=
=
=
=
=
NOTE:
16 (60)
Celsius
Fahrenheit
Inch
Pound per square foot
Millimeter
Pascal
For additional information, refer to NESC Table 250-1.
Extreme Wind Loading
Extreme wind loading in Table 5.13 applies to structures or support facilities that exceed
18.3 meters (m [60 feet (ft)]) above ground or water level. Please note that exceptions to
these extreme wind loading guidelines may apply and shall be determined by the designer
in cooperation with the AHJ.
NOTE:
The designer should identify codes, standards, and regulations that offer tables
containing safety factors used with overload conditions.
OSP Design Reference Manual, 4th edition
5-90
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Storm Load Requirements, continued
Required Pole Strength
Poles subjected to heavy transverse loads tend to break at ground level. Selecting poles with
sufficient strength at ground level to withstand transverse loads is a major consideration for
the designer.
The design strength of a pole at any given point is a function of its rated optical fiber stress
and its circumference. The higher the rated optical fiber stress and the larger the pole
circumference, the greater the transverse load that the pole will be able to withstand.
Transverse loads that must be considered are those caused by wind pressure on:
•
Cable and support strand.
•
Pole-mounted equipment and service drops.
•
The pole.
Moment Strength
Each transverse load causes a moment on the pole that tends to move the pole in the direction
of the applied load. The value of that moment in newton-meters (N-m) or equivalent in pound
force-feet (lbf-ft) is equal to the transverse load in newtons (N) or equivalent in lbf-ft
multiplied by the distance in meters from the load point to the point where the moment is being
considered. One lbf-ft equals 1.36 N-m.
The moments caused by each of the transverse loads must be summed together to obtain the
total load. A pole with sufficient resistant moment must be selected to handle the total
moment. As far as the moment is concerned, the ground line is usually the critical point unless
the pole is extra narrow at some other point or a sidewalk anchor and down guy is employed.
The rated breaking strength of the pole is based on the resistant moment that the pole can
withstand at ground level.
Method of Summing Loads
A systematic method of summing loads on a pole is to convert all transverse loads into
equivalent loads at a point 0.6 m (2 ft) from the top of the pole. A pole that has a breaking
strength capable of withstanding the sum of all the equivalent loads at a point 0.6 m (2 ft)
from the top of the pole is then selected.
© 2007 BICSI®
5-91
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Pole Classification
To determine the class of poles required in a pole line, the designer should consider:
•
The total number of cables to be placed during the life of the pole line.
•
The total weight of the cables.
•
The size of the support strands.
•
Any guy requirements (i.e., corners and deadends).
Using this information, the designer will be able to determine:
•
Species of wood.
•
Required pole height.
•
Desired preservation materials.
•
Required class (width/diameter).
Nine common pole classes used in OSP construction and their breaking strengths measured
610 mm (24 in) from top of pole are provided in Table 5.14.
Table 5.14
Pole class and transverse breaking strength
Pole Class
Transverse Breaking Strength
N
lbf
1
20 017
(4,500)
2
16 458
(3,700)
3
13 345
(3,000)
4
10 676
(2,400)
5
8452
(1,900)
6
6672
(1,500)
7
5338
(1,200)
9
3292
(740)
10
1646
(370)
lbf = Pound-force
N = Newton
Poles used as push braces or stubs for overhead guys should be the same class as the
poles they brace. From both cost and strength perspectives, using class 7 poles for most OSP
applications is acceptable.
OSP Design Reference Manual, 4th edition
5-92
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Numerical Classification of Poles
A numerical system of classifying poles has been established to standardize pole types and
facilitate selection of poles for specific applications. This system is based on nine pole classes
used in telecommunications. The classes are numbered 1 through 10 with the class 8 poles
omitted.
The rated breaking strength and dimensions distinguish pole classes. Breaking strength is
specified in terms of placing a load 0.6 m (2 ft) from the top of the pole. Table 5.15 lists
breaking strengths for pole classes 1 through 7.
Although a definite breaking strength for classes 9 and 10 is not specified, the values listed in
Table 5.15 for those classes are considered minimum acceptable values for pole selection.
Class 8 is not used because the rated breaking strength of class 7 and class 9 leave little room
for another class between the two (i.e., class 7 is rated at 5338 N [1200 lbf] and class 9 is
rated at 3292 N [740 lbf]). This table also provides conversion of breaking load to resistant
moment for various pole heights.
Numerical classifications listed in Table 5.15 are valid for all poles regardless of the species or
length. This implies that a class 7 southern (yellow) pine pole and a class 7 northern white
cedar pole (see Table 5.16) both have a rated breaking strength of 544.31 kilograms (kg [1200
pounds (lb)]). Poles measuring 6 m (20 ft) and 10.7 m (35 ft) in either species also have a
rated breaking load of 544.31 kg (1200 lb) using standard pole setting. See Table 5.17 for
resistance moments of various sizes of poles.
© 2007 BICSI®
5-93
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Numerical Classification of Poles, continued
Table 5.15
Pole resistance moments
Breaking
Load
Minimum
Circumference
at Top
20
Pole Height
Class
(pounds)
(inches)
1
4500
27
63,000
81,000
101,250
121,500
2
3700
25
51,800
66,600
83,250
3
3000
23
42,000
54,000
4
2400
21
33,600
5
1900
19
6
1500
7
50
70
144,000
184,500
265,500
284,900
99,900
118,400
151,700
218,300
346,500
67,500
81,000
96,000
123,000
177,000
231,000
43,200
54,000
64,800
76,800
98,400
141,600
184,800
26,600
34,200
42,750
51,300
60,800
77,900
112,100
146,300
17
21,000
27,000
33,750
40,500
48,000
61,500
88,500
115,500
1200
15
16,800
21,600
27,000
32,400
38,400
49,200
70,800
92,400
9
740
15
10,360
13,320
16,650
19,980
23,680
30,340
43,660
56,980
10
370
12
5,180
6,660
8,325
9,990
11,840
15,170
21,830
28,490
NOTE:
25
30
35
40
90
Resistant Movement (pound-feet)
This table is based on a load 0.6 m (2 ft) from the top of the pole and a standard
setting.
Table 5.16
Rated fiber strength for pole species
Pole Species
Rated
Fiber
Strength
(psi)
Average
Circumference
Taper
(inches per foot
of length)
Southern (yellow) pine (SP)
7,400
0.35
Lodgepole pine (LP)
6,600
0.3
Douglas fir (DF)
7,400
0.21
Western red cedar (WC)
5,600
0.38
Jack pine (JP)
6,600
0.3
Northern white cedar (EC)
3,600
0.3
Red (Norway) pine (NP)
6,600
0.3
Ponderosa pine (WP)
6,000
0.29
Western larch
8,400
0.21
OSP Design Reference Manual, 4th edition
5-94
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Numerical Classification of Poles, continued
Table 5.17
Resistance moments for various sizes of poles
Pole
Circumference
(Inches)
3,600
4,600
5,600
6,000
6,600
7,400
8.0
487
622
757
811
892
1000
8.5
584
746
908
973
1070
1200
9.0
693
885
1080
1150
1270
1420
9.5
815
1040
1270
1360
1490
1680
10.0
950
1210
1480
1580
1740
1950
10.5
1100
1410
1710
1830
2020
2260
11.0
1300
1620
1970
2110
2320
2600
11.5
1450
1850
2250
2410
2650
2970
12.0
1640
2100
2650
2740
3010
3380
12.5
1860
2370
2890
3090
3400
3810
13.0
2090
2670
3250
3480
3830
4290
13.5
2340
2990
3640
3900
4280
4810
14.0
2610
3330
4060
4350
4780
5360
14.5
2900
3700
4510
4830
5310
5960
15.0
3210
4100
4990
5350
5880
6590
15.5
3540
4520
5510
5900
6490
7280
16.0
3890
4970
6060
6480
7140
8000
16.5
4270
5460
6640
7120
7830
8780
17.0
4670
5970
7260
7780
8560
9600
17.5
5090
6510
7920
8490
9340
10,500
18.0
5540
7080
8620
9240
10,200
11,400
18.5
6020
7690
9360
10,000
11,000
12,400
19.0
6520
8330
10,100
10,900
11,900
13,400
19.5
7050
9000
11,000
11,700
12,900
14,500
20.0
7600
9720
11,800
12,700
13,900
15,600
20.5
8190
10,500
12,700
13,600
15,000
16,800
21.0
8800
11,200
13,700
14,700
16,100
18,100
21.5
9450
12,100
14,700
15,700
17,300
19,400
22.0
10,100
12,900
15,700
16,900
18,500
20,800
© 2007 BICSI®
5-95
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Numerical Classification of Poles, continued
Table 5.17
Resistance moments for various sizes of pole, continued
Pole
Circumference 3,600
(Inches)
4,600
5,600
6,000
6,600
7,400
22.5
10,800
13,800
16,800
18,400
19,800
22,300
23.0
11,600
14,800
18,000
19,200
21,200
23,800
23.5
12,300
15,800
19,200
20,600
22,600
25,400
24.0
13,100
16,800
20,400
21,900
24,100
27,000
24.5
14,000
17,900
21,700
23,300
25,600
28,700
25.0
14,900
19,000
23,100
24,700
27,200
30,500
25.5
15,800
20,100
24,500
26,300
28,900
32,400
26.0
16,700
21,300
26,000
27,800
30,600
34,300
26.5
17,700
22,600
27,500
29,500
32,400
36,400
27.0
18,700
23,900
29,100
31,200
34,300
38,500
27.5
19,800
25,300
30,700
32,900
36,200
40,600
28.0
20,900
26,700
32,500
34,800
38,200
42,900
28.5
22,000
28,100
34,200
36,700
40,300
45,200
29.0
23,200
29,600
36,100
35,600
42,500
47,600
29.5
24,400
31,200
38,000
40,700
44,700
50,200
30.0
25,700
32,800
39,900
42,800
47,000
52,800
30.5
27,000
34,500
41,900
44,900
49,400
55,400
31.0
28,300
36,200
44,000
47,200
51,900
58,200
31.5
29,700
38,000
46,200
49,500
54,500
61,100
32.0
31,100
39,800
48,400
51,900
57,100
64,000
32.5
32,600
41,700
50,800
54,400
59,800
67,100
33.0
34,200
43,600
53,100
56,900
62,600
70,200
33.5
35,700
45,700
55,600
59,500
65,500
73,400
34.0
37,400
47,700
58,100
62,300
68,500
76,800
34.5
39,000
49,900
60,700
65,000
71,500
80,200
35.0
40,700
52,100
63,400
67,900
74,700
83,800
35.5
42,500
54,300
66,100
70,900
78,000
87,400
36.0
44,300
56,700
69,000
73,900
81,300
91,000
OSP Design Reference Manual, 4th edition
5-96
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Numerical Classification of Poles, continued
Table 5.17
Resistance moments for various sizes of pole, continued
Pole
Circumference 3,600
(Inches)
4,600
5,600
6,000
6,600
7,400
36.5
46,200
59,100
71,900
77,000
84,700
95,000
37.0
48,100
61,500
74,900
80,200
88,300
99,000
37.5
50,100
64,000
78,000
83,500
91,900
10,300
38.0
52,200
66,600
81,100
86,900
95,600
107,200
38.5
54,200
69,300
84,400
90,400
99,400
111,500
39.0
56,400
72,000
87,700
94,000
103,400
115,900
39.5
58,600
74,800
91,100
97,600
107,400
120,400
40.0
60,800
77,700
94,600
101,400
111,500
125,000
40.5
63,100
80,700
98,200
105,200
115,700
129,800
41.0
65,500
83,700
101,900
109,200
120,100
134,600
41.5
67,900
86,800
105,700
113,200
124,500
139,600
42.0
70,400
90,000
109,500
117,400
129,100
144,700
42.5
73,000
93,200
113,500
121,600
133,800
150,000
43.0
75,600
96,600
117,500
125,900
138,500
155,300
43.5
78,200
100,000
121,700
130,400
143,400
160,800
44.0
81,000
103,400
125,900
134,900
148,400
166,400
44.5
83,800
107,000
130,300
139,600
153,500
172,200
45.0
86,600
110,700
134,700
144,400
158,800
178,000
45.5
89,500
114,400
139,300
149,200
164,200
184,000
46.0
92,500
118,200
143,900
154,200
169,600
-------
46.5
97,600
122,100
148,600
159,300
175,200
196,400
47.0
98,700
126,100
153,100
164,500
180,900
202,800
47.5
101,900
130,100
158,400
169,800
186,700
209,400
48.0
105,100
134,300
163,500
175,200
192,700
216,100
48.5
108,400
138,500
168,700
180,700
198,800
222,900
49.0
111,800
142,900
173,900
185,400
205,000
229,800
© 2007 BICSI®
5-97
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Numerical Classification of Poles, continued
Table 5.17
Resistance moments for various sizes of pole, continued
Pole
Circumference 3,600
(Inches)
4,600
5,600
6,000
6,600
7,400
49.5
115,300
147,300
179,300
192,100
211,300
236,900
50.0
118,800
151,800
184,800
198,000
217,800
244,200
50.5
122,400
156,400
190,400
204,000
244,000
251,600
51.0
126,100
161,100
196,100
210,100
231,100
259,100
51.5
129,800
165,900
201,900
216,400
238,000
266,800
52.0
133,600
170,800
207,900
222,700
245,000
274,700
52.5
137,500
175,700
213,900
229,200
252,100
282,700
53.0
141,500
180,800
220,100
235,800
259,400
290,800
53.5
145,500
186,000
226,400
242,600
266,800
299,200
54.0
149,700
191,200
232,800
249,200
274,400
307,600
54.5
153,800
196,600
239,300
256,400
282,100
316,200
55.0
158,100
202,000
246,000
263,500
289,900
325,000
55.5
162,500
207,600
252,700
270,800
297,900
334,000
56.0
166,900
213,300
259,600
278,200
306,000
343,100
56.5
171,400
219,000
266,600
285,700
314,300
352,400
57.0
176,000
224,900
273,800
293,300
322,700
361,800
57.5
180,700
230,900
281,100
301,100
331,200
371,400
58.0
185,400
236,900
288,500
309,100
340,000
381,200
58.5
190,300
243,100
296,000
317,100
348,800
391,100
59.0
195,200
249,400
303,600
325,300
357,900
401,200
59.5
200,200
255,800
311,400
333,700
367,000
411,500
60.0
205,300
262,300
319,300
342,100
376,400
422,000
OSP Design Reference Manual, 4th edition
5-98
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Pole Depth Belowground
To provide the resistant moment referred to in the paragraphs above, the pole must have a
sufficient segment of its length implanted in the ground. This offsets the force from the wind,
ice, apparatus cases, transformers, or other loadings.
The pole hole shall be of sufficient diameter to permit the pole to settle freely to the bottom of
the hole without trimming the butt and still have sufficient space between the pole and the
sides of the hole to permit proper tamping of the backfill at every point around the pole, and
throughout the entire depth of the hole. The setting depth, in meters (with equivalent in feet),
for poles of various lengths is shown in Table 5.18.
Table 5.18
Pole setting depth required for various heights
Length of Pole
m/ft
Setting in Soil
m/ft
Setting in Solid Rock
m/ft
6 (20)
1.2 (4.0)
0.91 (3)
7.6 (25)
1.52 (5.0)
1.07 (3.5)
9 (30)
1.7 (5.5)
1.07 (3.5)
10.7 (35)
1.83 (6.0)
1.2 (4.0)
12 (40)
1.83 (6.0)
1.2 (4.0)
13.7 (45)
1.98 (6.5)
1.4 (4.5)
15 (50)
2.1 (7.0)
1.4 (4.5)
16.8 (55)
2.3 (7.5)
1.52 (5)
18.3 (60)
2.4 (8.0)
1.52 (5)
ft = Foot
m = Meter
© 2007 BICSI®
5-99
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Depth Requirement
The setting in soil depth as shown in Table 5.18 applies when:
•
Poles are to be set in soil only.
•
There is a layer of soil more than 0.6 m (2 ft) in depth over solid rock.
•
The pole in solid rock is substantially vertical.
•
The diameter of the hole at the surface of the rock exceeds approximately twice the
diameter of the pole at the same level.
The setting in solid rock depth applies where solid rock is encountered at the ground line and
where the hole is substantially vertical, approximately uniform in diameter, and large enough to
permit the use of tamping bars the full depth of the hole.
Where there is a layer of soil 0.6 m (2 ft) or less in depth over solid rock, the depth of
the hole shall be the depth of the soil in addition to the depth specified in setting in solid rock
provided; however, such depth shall not exceed the depth specified under setting in soil.
OSP Design Reference Manual, 4th edition
5-100
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Depth Requirement, continued
On sloping ground, the depth of the hole should be measured from the low side of the hole.
When a pole is to be set on the side of a steep grade where soil erosion is a consideration,
the hole should be 0.3 m (1 ft) deeper than specified under setting in soil.
Holes in soil for poles at unguyed corners where the pole will not be keyed shall be 0.3 m
(1 ft) deeper than the setting in soil depth. For holes in solid rock the setting in solid rock
depth will apply.
NOTE:
See Figure 5.41 for an example of keying. The process amounts to bolting a
horizontal member (e.g., wood or a nonrusting substance) to the pole 152 mm (6 in)
below the ground line to provide a resistance to torsional forces.
Figure 5.41
Example of keying a pole
Wood pole key
© 2007 BICSI®
5-101
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Compaction
When an earth boring machine is used to dig holes for guyed poles, the bottom of the hole
must be thoroughly tamped to compact any loose earth. All holes must be backfilled with soil
or small rock.
Backfill shall be thoroughly tamped the full depth of the pole hole. Earth must be banked
around the pole to a minimum height of 152 mm (6 in) above ground level.
Holes in soil for poles at unguyed corners where the pole will not be keyed shall be 0.3 m
(1 ft) deeper than the setting in soil depth. The setting in solid rock depth applies to holes in
solid rock.
Poles should be set plumb (vertical) except at corners where they shall be set and raked
against the load so that the pole top will be in line with the lead of the line after the load is
applied. The rake in pole must not exceed 152 mm (6 in) for each 3 m (10 ft) of pole length
after the conductors are installed at the required tension. The deadend shall be set so as to be
plumb and in line after the load is applied.
Adding moisture may aid in the compaction of soil.
NOTE:
See Chapter 7: Grounding, Bonding, and Protection for grounding (earthing) and
bonding requirements.
Transverse Load on a Pole from Aerial Line
The transverse load imposed on a pole by the aerial line is the result of wind pressure on the
line. This load per foot of span length is P multiplied by D.
Where:
P is wind pressure in kilograms per square meter (kg/m2 [pounds per square foot
(lb/ft2)]), and
D is diameter of the aerial line (including ice coating) in meters/feet (m/ft)
To calculate the actual transverse load, the designer must multiply the product of P and D by
the span length (S). Where the span lengths on both sides of the pole are not equal, the
average of the two span lengths should be used.
Storm-Loading Districts
The transverse load equation for the three storm-loading districts based on Table 5.19 is
PD (lb/ft) = 0.75d, where D is wire/cable diameter, including support strand, in millimeters and
equivalent in inches.
Storm-loading districts may have areas where heavier or lighter loadings than are indicated for
that district prevail. In those areas, the designer must alter the requirements set for the loading
district to comply with local conditions. The conditions must not be decreased without written
approval from the AHJ.
Storm-loading districts should be determined through coordination with the local meteorological
service for that country.
OSP Design Reference Manual, 4th edition
5-102
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Transverse Load on a Pole from Aerial Line, continued
Load Table
Typical values of transverse load as a result of storm loading on cables and support strands
are shown in Table 5.19.
Table 5.19
Transverse load on pole (kg/m per lb/ft of span length)
Support Strand or Cable
Heavy
Medium
Light
Support strand
kg/m (lb/ft)
kg/m (lb/ft)
kg/m (lb/ft)
6M
0.20 (0.44)
0.12 (0.27)
0.10 (0.23)
10M
0.21 (0.46)
0.13 (0.28)
0.12 (0.28)
16M
0.22 (0.48)
0.14 (0.31)
0.14 (0.31)
25M
0.23 (0.50)
0.15 (0.33)
0.16 (0.36)
Less than 1 inch cable (6M)
0.35 (0.77)
0.27 (0.60)
0.44 (0.98)
1.0–1.9 in cable (6M)
0.50 (1.10)
0.43 (0.94)
0.79 (1.74)
2.0 in or greater cable (6M)
0.65 (1.44)
0.58 (1.27)
1.12 (2.48)
Less than 1 in cable (10M)
0.35 (0.77)
0.28 (0.62)
0.47 (1.04)
1.0–1.9 in cable (10M)
0.51 (1.12)
0.44 (0.96)
0.81 (1.78)
2.0 in or greater (10M)
0.66 (1.46)
0.59 (1.29)
1.15 (2.53)
Less than 1 in cable (16M)
0.37 (0.81)
0.29 (0.64)
0.49 (1.08)
1.0–1.9 in cable (16M)
0.52 (1.14)
0.44 (0.98)
0.83 (1.83)
2.0 in or greater cable (16M)
0.67 (1.48)
0.59 (1.31)
1.17 (2.57)
Less than 1 in cable (25M)
0.38 (0.83)
0.30 (0.67)
0.51 (1.13)
1.0–1.9 in cable (25M)
0.83 (1.17)
0.45 (1.00)
0.85 (1.87)
2.0 in or greater cable (25M)
0.68 (1.50)
0.60 (1.33)
1.19 (2.63)
100 pair, 26 gauge
0.34 (0.76)
0.27 (0.59)
0.44 (0.96)
50 pair, 22 gauge
0.35 (0.77)
0.28 (0.61)
0.45 (1.00)
300 pair, 26 gauge
0.39 (0.87)
0.32 (0.71)
0.55 (1.22)
Lashed cable, including support strand
Self-supporting cable
ft
kg
lb
m
© 2007 BICSI®
=
=
=
=
Foot
Kilogram
Pound
Meter
5-103
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Transverse Load on a Pole from Aerial Line, continued
Moment
The moment Mw in kilogram-meters (pound-feet) at ground level caused by a transverse load
on the pole from the wires/cables is defined by the following equation:
Mw = PDSLN
Where:
P is wind pressure in kilograms per square meter (pounds per square feet);
D is diameter of the line (support strand, cable, and wire) in meters (feet);
S is span length;
L is height of line attachment aboveground m (ft); and,
N is number of equivalent lines.
Table 5.20 gives the product of P multiplied by D for commonly used conductors. To obtain
the total moment, the product should be multiplied by S, L, and N. In case of two or more
types of conductors, the moment for each type should be computed and added up.
Transverse Load from Wind Pressure on Pole
The moment Mp in kilogram-meters (pound-feet) at ground level as a result of wind pressure
on the pole may be calculated by the following equation:
Mp = PH (2Ct + Cg)
Where:
P is wind pressure kilograms per square meter (pounds per square feet);
H is height of pole above ground in meters (feet);
Ct is circumference of pole at top in millimeters (inches); and,
Cg is circumference of pole at ground level in millimeters (inches).
Assumed Load
As calculated by the above formula, the transverse load on a pole caused by wind against
the pole will always be a very small percentage of the breaking strength of the pole.
Accordingly, a highly accurate value is not required. For routine design purposes, bending
moments of 207 kilogram force-meters (kgf-m [1500 pound force-feet (lbf-ft)]) in the heavy
and medium storm-loading districts and a 414 kgf-m (3000 lbf-ft) in the light storm-loading
district are assumed.
OSP Design Reference Manual, 4th edition
5-104
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Loads Imposed by Service Drop Wires
Unbalanced Service Drop Wires
Service drop wires impose transverse loads on poles. Where the angle of departure between a
service drop wire and the line wire is 45 degrees or less, the drop wire is considered as the
line wire. Where the angle of departure between a service drop wire and the line wire is
greater than 45 degrees, the drop wire is considered to impose a transverse load on the pole.
The transverse load per meter/foot for unbalanced service drop wires is:
•
0.09 kg (0.20 lb) in the medium/heavy storm-loading district.
•
0.07 kg (0.16 lb) in the light storm-loading district.
Balanced Drop Wires
Balanced loads are line attachment loads that are offset by an equal holding force applied to
the opposite side of the pole. When the same type of telecommunications service drop wires
are attached to opposite sides of a pole, the transverse loads caused by those drop wires are
balanced.
In this case, the pole acts like a strut, supporting only the vertical load caused by the weight of
the wires/cables and transverse attachments, including ice load.
Loads Imposed by Pole Attachments
Certain types of pole attachments, such as cable terminals and loading coil cases, cause a
transverse load on the pole. Table 5.20 provides loads in kilograms per square meter (pounds
per square foot) for various storm-loading districts. As an alternative, the load can be included
in the formula in the section titled Moment by increasing N or number of equivalent lines. To
find the equivalent N for an attachment, the projected area of the attachment is divided by the
projected area of one span of bare wire.
Table 5.20
Load imposed by pole attachment
Storm-Loading District
Load per kg/m2 (lb/ft2) of projected area
Heavy
Medium
Light
4
4
9
kg/m 2 = Kilogram per square meter
lb/ft2 = Pound per square foot
© 2007 BICSI®
5-105
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Transverse Load Calculation
Every pole must be selected to withstand the transverse moment attempting to break the pole
at ground level. The amount of bending moment at ground level is equal to the sum of the
moments produced by the wires/cables (Mw), pole equipment and service drops (Me), and the
pole (Mp). To determine the required resistant moment, the value of the bending moment
applied to the pole is multiplied by the factor of safety (FS) set for specific conditions. The
formula is:
Mr = (Mw + Me + Mp) FS
Where:
Mw is wires and cables;
Me is pole equipment and service drop;
Mp is pole; and,
FS is factor of safety
Conditions
The following illustrates the calculation of required pole strength for a given transverse load,
assuming the indicated conditions:
•
A 107 m (351 ft) average span
•
Two 58 mm (2.3 in) cables lashed to a 10M support strand
•
A 9 m (30 ft) unguyed pole is used
•
Height of cable above ground is 7.3 m (24 ft)
•
Grade B construction
•
Heavy storm-loading district
•
No pole equipment or service drops
Calculation
The formula for Mw is used with the numerical values given under Conditions.
Where:
PD = 2.18 kgf-m (1.46 lbf-ft) of span length (See heavy storm-loading in
Table 5.19.)
S = 107 m (351 ft)
L = 7.3 m (24 ft)
N=2
Then:
Mw = 1.46 × 351 ft × 24 ft × 2 = 24,528 lbf-ft
Mw = 2.19 × 107 m × 7.3 m × 2 = 3421 kgf-m
OSP Design Reference Manual, 4th edition
5-106
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Transverse Load Calculation, continued
Estimation
The bending moment caused by wind on the pole (Mp) is assumed to be 207 kgf-m (1500 lbfft) in the heavy storm-loading area.
Required Resistant Moment
Substituting the formula for transverse load calculation,
Where:
Mw = 3411 kgf-m (24,528 lbf-ft)
M e= 0
Mp= 207 kgf-m (1500 lbf-ft)
FS = 1.33 for grade B construction
Then:
Mr = (24,528 lbf-ft + 1500 lbf-ft) × 1.33 = 34,617 lbf-ft
Mr = (3411 kgf-m + 207 kgf-m) × 1.33 = 4812 kgf-m
Selection
Selection of Pole Class
As indicated in the previous calculations, a 9 m (30 ft) pole must have sufficient strength to
withstand an applied bending moment of 4812 kgf-m (34,617 lbf-ft) at the ground line. As
shown in Table 5.14, a class 6, 9 m (30 ft), pole has the closest resistant moment, 4692 kgf-m
(33,750 lbf-ft), which is insufficient to support the applied moment. A class 5, 9 m (30 ft), pole,
which has a resistant moment of 5973 kgf-m (42,750 lbf-ft) must be used.
NOTE:
© 2007 BICSI®
Since optical fiber cable is lighter than balanced twisted-pair cables, the final result
of the formulas above often will suggest usage of class 9 or class 10 poles. However, they should not be used. These poles have very small diameters and are rarely
used except as temporary poles. Class 7 or larger poles should be used.
5-107
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Vertical Load
Vertical loads on poles may be caused by any combination of loading factors. These
factors include anchor guying and the dead weight of wires, cables, and other attachments
on the poles.
As a general rule, vertical loads caused by conductors and pole attachments need not be
considered in pole line design; however, these loads should be considered in the case of guyed
poles. The most severe vertical load to which a guyed pole may be subjected is the vertical
component of the tension in the guy or guys. For purposes of pole selection, the maximum
tension in the guy is usually assumed to be the minimum breaking strength of the guy.
Table 5.21 may be used to determine the minimum pole class.
Table 5.21
Minimum pole class to support vertical load
Length of Pole m (ft)
9
10.7
12
(30)
(35)
(40)
Vertical Load
kg/lb
6
(20)
7.6
(25)
13.7
(45)
15
(50)
2268 (5000)
10
9
9
7
7
7
7
4536 (10,000)
9
9
7
7
7
6
6
6804 (15,000)
9
7
7
6
6
5
5
9072 (20,000)
7
7
6
6
5
5
4
13 608 (30,000)
6
6
5
5
4
4
3
22 680 (50,000)
5
4
4
3
3
2
2
45 360 (100,000)
3
2
1
1
1
-
-
26
(85)
27.4
(90)
Length of Pole m (ft)
19.8 21.3
23
24
(65) (70) (75)
(80)
Vertical Load
kg/lb
16.8
(55)
18.3
(60)
2268 (5000)
6
6
5
5
4
4
3
3
4536 (10,000)
6
5
5
5
3
3
3
2
6804 (15,000)
5
4
4
4
2
2
2
1
9072 (20,000)
4
4
4
3
1
1
1
-
13 608 (30,000)
3
3
2
2
-
-
-
-
22 680 (50,000)
1
1
1
1
-
-
-
-
45 360 (100,000)
-
-
-
-
-
-
-
-
ft
kg
lb
M
=
=
=
=
Foot
Kilogram
Pound
Meter
OSP Design Reference Manual, 4th edition
5-108
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Bending Moments (Longitudinal Loads)
Bending moments on a pole are caused by an unbalanced tension in the line. This load can be
calculated at any point on the pole.
The bending moment on an unguyed pole is equal to the sum of the total unbalance of the
longitudinal tensions in the conductors. When the pole is not guyed, any longitudinal load on the
pole at the point of wire/cable attachments causes a bending moment at the ground line. To
find the longitudinal load on an unguyed pole, apply the following formula:
M=T×L
Where:
M is total bending moment in kilogram force-meters (pound force-feet) at the
ground line caused by longitudinal loading;
T is total unbalanced force in kilograms (pounds) of conductor tensions; and,
L is height in meters (feet) of wire/cable attachment above the ground.
Calculation of Pole Height
The height of a pole depends on many factors. The main considerations are the:
•
Type of conductors it supports.
•
Conductor configuration.
•
Conductor voltage.
•
Nature of the ground beneath the conductors.
•
Depth of the pole setting.
•
Topography of the ground.
•
Restrictions that may be placed upon the height of wires (e.g., nearby radio facilities,
aviation activity).
•
Equipment mounted on the pole.
•
Attachment clearances.
Attachment Space
Pole height should provide sufficient space for the maximum number of attachments that will
be made during the service life of the pole line. The attachment space must include the space
between the top of the pole, as well as the highest and lowest attachments.
For pole lines supporting cable, 457 mm (18 in) should be provided at the top of the pole and
305 mm (12 in) for each cable attachment.
© 2007 BICSI®
5-109
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Pole Spacing and Span Lengths
In determining spacing and span lengths, the designer should consider the:
•
Total number of cables to be placed during the life of the pole line.
•
Total weight of the cables.
•
Size of the support strands.
•
Climatic conditions.
•
Loading conditions.
•
Minimum ground clearance.
Other factors that may impact the maximum span lengths include:
•
The length of a city block.
•
Driveways.
•
Property lines.
•
Terminal requirements.
•
Terrain.
•
Ground clearance.
•
Branch cables.
•
Corners.
•
Joint-use requirements.
Equal distance spacing of poles in a pole line is not required. However, poles should be placed
utilizing terrain features to allow for maximum span length with minimum height poles as
shown in Figure 5.42.
Figure 5.42
Pole placement utilizing terrain feature
Greater ground clearance
with shorter poles
Correct placement of poles
Taller poles required to maintain
minimum ground clearance
Incorrect placement of poles
OSP Design Reference Manual, 4th edition
5-110
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Pole Spacing and Span Lengths, continued
Tables 5.22 through 5.26 may be referenced to calculate maximum span lengths and the total
weight of the cable(s).
SAMPLE:
An existing pole line has 1 BKMA-200 and 1 BKTA-100 on separate, 6M
strands. One additional BKTS-100 is planned for the pole line. The average
span length for the pole line is 91 m (300 ft). As shown in Table 5.22, a
BKTS-100 has a maximum span limit of 100 m (328 ft). Therefore, from the
standpoint of span lengths, the pole line will be sufficient for the placement of
the proposed cable.
These tables are based on average weights. Check with the cable manufacturer for exact
weights.
Table 5.22
Maximum span lengths for self-supporting cable
Pairs
19
BHBS
m (ft)
22
BHAS
m (ft)
24
BKMS
m (ft)
26
BKTS
m (ft)
19
BHBP
m (ft)
22
BHAP
m (ft)
24
BKMP
m (ft)
26
BKTP
m (ft)
25
145 (476)
168 (550) 183 (600)
198 (650)
122 (400)
145 (476) 145 (476)
152 (500)
50
114 (374)
145 (476) 168 (550)
183 (600)
107 (351)
122 (400) 130 (427)
145 (476)
100
114 (374)
130 (427) 152 (500)
101 (331)
114 (374)
130 (427)
200
107 (351)
122 (400) 107 (351)
94 (308)
107 (351)
300
107 (351)
96 (315)
ft = Foot
M = Meter
NOTE: For an explanation of cable description codes, see Cable Construction Types in
Chapter 4: Cabling Infrastructure.
© 2007 BICSI®
5-111
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Total Weight and Maximum Span Lengths of the Cable
Use Tables 5.23 through 5.26 to calculate the total weight.
Table 5.23
Pole span length/tension
Installation Temperature °F
0
20
40
60
80
100
Span
Length
Tension
Sag
Tension
Sag
Tension
Sag
Tension
Sag
Tension
Sag
Tension
Sag
ft
lbf
in
lbf
in
lbf
in
lbf
in
lbf
in
lbf
in
100
1861
17
1799
18
1738
18
1680
19
1622
20
1566
20
125
2011
24
1954
25
1897
26
1843
27
1789
28
1736
29
150
2160
33
2108
34
2054
35
2002
36
1952
37
1902
38
175
2307
42
2257
43
2207
44
2158
45
2110
46
2062
47
200
2452
52
2406
53
2358
54
2311
55
2264
57
2218
58
225
2593
63
2549
64
2504
65
2457
66
2411
67
2365
69
250
2730
74
2686
75
2642
76
2596
77
2551
79
2506
80
275
2862
84
2820
86
2776
88
2732
89
2688
91
2645
92
ft = Foot
in = Inch
lbf = Pound-force
OSP Design Reference Manual, 4th edition
5-112
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Total Weight and Maximum Span Lengths of the Cable, continued
Table 5.24
Weight for ALPETH cable
Part
Number
Pair
Count
Nominal
Outside Diameter
mm (in)
Approximate
Weight
kg/km (lbs/kf)
85-031-01
25
19 (0.75)
453 (305)
85-034-01
50
25 (1.00)
846 (568)
85-038-01
100
34 (1.35)
1597 (1073)
85-042-01
200
47 (1.86)
3121 (2098)
85-44-01
300
57 (2.25)
4609 (3098)
85-046-01
400
66 (2.6)
6095 (4096)
85-062-01
25
15 (0.59)
258 (174)
85-065-01
50
19 (0.75)
459 (308)
85-069-01
100
25 (1.00)
853 (573)
85-073-01
200
34 (1.35)
1630 (1095)
85-075-01
300
41 (1.6)
2391 (1607)
85-077-01
400
47 (1.85)
3147 (2115)
85-081-01
600
57 (2.25)
4680 (3145)
85-083-01
900
69 (2.71)
6939 (4663)
85-097-01
25
12 (0.47)
180 (121)
85-100-01
50
16 (0.63)
314 (211)
85-104-01
100
21 (0.81)
567 (981)
85-108-01
200
28 (1.09)
1067 (717)
85-110-01
300
33 (1.3)
1568 (1054)
85-112-01
400
37 (1.47)
2056 (1381)
85-116-01
600
45 (1.75)
3025 (2033)
85-118-01
900
55 (2.15)
4467 (3002)
85-120-01
1200
63 (2.46)
5891 (3959)
19 AWG
[0.91 mm (0.036 in)]
22 AWG
[0.64 mm (0.025 in)]
24 AWG
[0.51 mm (0.020 in)]
© 2007 BICSI®
5-113
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Total Weight and Maximum Span Lengths of the Cable, continued
Table 5.24
Weight for ALPETH cable, continued
Part
Number
Pair
Count
Nominal
Outside Diameter
mm (in)
Approximate
Weight
kg/km (lbs/kf)
26 AWG
[0.41 mm (0.016 in)]
85-132-01
25
10 (0.39)
127 (85)
85-135-01
50
13 (0.52)
214 (144)
85-139-01
100
17 (0.67)
374 (252)
85-143-01
200
22 (0.87)
691 (464)
85-145-01
300
26 (1.04)
1012 (680)
85-147-01
400
30 (1.18)
1324 (889)
85-151-01
600
36 (1.42)
1929 (1296)
85-153-01
900
44 (1.72)
2837 (1906)
85-155-01
1200
50 (1.96)
3725 (2503)
85-156-01
1500
55 (2.18)
4618 (3104)
85-157-01
1800
60 (2.37)
5510 (3703)
in
kf
kg
km
lb
mm
=
=
=
=
=
=
Inch
Kilofoot
Kilogram
Kilometer
Pound
Millimeter
OSP Design Reference Manual, 4th edition
5-114
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Total Weight and Maximum Span Lengths of the Cable, continued
Table 5.25
Cable weight for self-supporting cable
Part
Number
Pair
Count
Nominal
Outside Diameter
mm (in)
Minor
BHBS - 19 AWG
Major
[0.91 mm (0.036 in)]
20-026-43
6
12 (0.47)
24 (0.95)
422 (283)
20-031-43
25
15 (0.59)
27 (1.07)
731 (491)
20-034-43
50
25 (1)
37 (1.45)
1042 (700)
BHAS - 22 AWG
[0.64 mm (0.025 in)]
20-062-43
25
15 (0.59)
27 (1.07)
461 (310)
20-065-43
50
19 (0.75)
31 (1.22)
662 (445)
20-069-43
100
25 (1)
37 (1.45)
1049 (705)
BKMS - 24 AWG
[0.51 mm (0.020 in)]
20-097-43
25
12 (0.47)
24 (0.95)
387 (260)
20-100-43
50
16 (0.63)
28 (1.09)
513 (345)
20-104-43
100
20 (0.80)
32 (1.25)
766 (515)
20-108-43
200
28 (1.09)
40 (1.56)
1250 (840)
BKTS - 26 AWG
in
kf
kg
km
lb
mm
Approximate
Weight
kg/km (lbs/kf)
[0.41 mm (0.016 in)]
20-132-43
25
11 (0.43)
23 (0.91)
381 (256)
20-135-43
50
13 (0.53)
25 (1)
417 (280)
20-139-43
100
17 (1.07)
29 (1.14)
580 (390)
20-143-43
200
24 (0.95)
36 (1.40)
964 (647)
20-145-43
300
32 (1.25)
44 (1.72)
1271 (853)
=
=
=
=
=
=
Inch
Kilofoot
Kilogram
Kilometer
Pound
Millimeter
© 2007 BICSI®
5-115
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Total Weight and Maximum Span Lengths of the Cable, continued
Table 5.26
Cable weight for self-supporting cable reinforced sheath
Part
Number
Pair
Count
Nominal
Outside Diameter
mm (in)
Minor
Major
Approximate
Weight
kg/km (lbs/kf)
BHBP - 19 AWG
[0.91 mm (0.036 in)]
20-026-20
6
21 (0.83)
33 (1.3)
562 (377)
20-031-20
25
30 (1.18)
42 (1.66)
940 (631)
20-034-20
50
35 (1.3)
47 (1.85)
1420 (953)
20-062-20
25
19 (0.75)
31 (1.21)
625 (420)
20-065-20
50
24 (0.95)
35 (1.3)
885 (595)
20-069-20
100
30 (1.18)
42 (1.64)
1332 (895)
20-097-20
25
17 (0.67)
28 (1.09)
528 (355)
20-100-20
50
20 (0.8)
32 (1.25)
692 (465)
20-104-20
100
25 (0.99)
37 (1.45)
977 (670)
20-108-20
200
32 (1.25)
44 (1.72)
1562 (1050)
20-132-20
25
15 (0.59)
27 (1.07)
454 (305)
20-135-20
50
18 (0.7)
29 (1.14)
573 (385)
20-139-20
100
21 (0.84)
33 (1.3)
774 (520)
20-143-20
200
28 (1.09)
39 (1.55)
1153 (775)
20-145-20
300
31 (1.22)
43 (1.69)
1495 (1005)
BHAP - 22 AWG
[0.64 mm (0.025 in)]
BKMP - 24 AWG
[0.51 mm (0.020 in)]
BKTP - 26 AWG
[0.41 mm (0.016 in)]
in
kf
kg
km
lb
mm
=
=
=
=
=
=
Inch
Kilofoot
Kilogram
Kilometer
Pound
Millimeter
OSP Design Reference Manual, 4th edition
5-116
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Special Situation Designs
Special design requirements are needed when working with:
•
C wire—Aerial 19 American wire gauge (AWG [0.91 mm (0.036 in)]) drop wire used for
extended span lengths.
•
Service drop wire—Service drop wire is either two-conductor or limited pair count aerial
wire that is extended to a residence, typically from an aerial run.
These items are lighter than cable and require less guying. Smaller class poles may be used.
Optical Fiber Cable Considerations
Although the following aerial cables would experience such tension under storm loading, the
maximum rated cable pulling tensions are:
•
For all cables, except self-supporting cable, 2.7 kilonewtons (kN [600 lbf]).
•
For figure-eight self-supporting cable 14.7 kN (3300 lbf).
•
For dielectric circular self-supporting cable 5.8 kN (1300 lbf).
NOTE:
© 2007 BICSI®
Consult the manufacturer for specific cable pull tension capabilities.
5-117
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Special Situation Designs, continued
Slack Span Design
As long as the last section is 30.5 m (100 ft) or less, a slack span design (see Figure 5.43)
may be used when it is not possible to terminate an aerial run with a deadend guy. By using
less than normal stringing tension in the final span, guying on that end can be omitted.
Situations that may require the use of slack span design include space deficiencies and R/W
problems.
Figure 5.43
Slack span
Slack span
Last section
Pole to pole slack span
Slack span
Last section
Pole to building slack span
OSP Design Reference Manual, 4th edition
5-118
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Special Situation Designs, continued
Pole to Building Design
In designing pole to building aerial spans, the critical point becomes the attachment to the
building (see Figure 5.44). If a solid terminating point for hardware attachment cannot be
found, a portion of a building’s masonry or framework may be dislodged.
Figure 5.44
Building attachment methods
Square
washer
NOTE: Holes are enlarged for clarity.
Sleeve
through
wall
Not less than
0.6 m (2 ft) from
corner
Guy bolt
Cable clamp
False
dead end
Seal entrance holes
around cable with
hydraulic cement.
152 mm (6 in)
to 203 mm (8 in)
152 mm (6 in)
to 203 mm (8 in)
U-wall strap
12.7 x 89 mm
(1/2 x 3-1/2 in)
Drive anchors
Use three-bolt guy clamp
with 6M strand.
Use one-bolt guy clamp
with 2.2M strand.
=
=
=
=
Plate wall strap
Strand grip
NOTE: Place strap in such a
position that anchors
will be approximately
at center of bricks.
Alternate method U wall strap
ft
in
m
mm
12.7 x 89 mm
(1/2 x 3-1/2 in)
Drive anchors
(See Note)
Alternate method plate wall strap
Foot
Inch
Meter
Millimeter
Using pole to building slack span construction is recommended for cables under 300 pairs.
For cables 300 pair or greater, an alternate route into the building should be selected.
© 2007 BICSI®
5-119
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Special Situation Designs, continued
Flying Cross Construction
A flying cross should be used when field conditions prevent placing a pole at a point of
intersection (see Figure 5.45).
Figure 5.45
Flying cross
EOP
Street
Support strand
Cable
Turn lane
Merge lane
Street
EOP
EOP
EOP = Edge of pavement
Clearances
A designer should be concerned with the following types of clearances:
•
Vertical clearances of cables, hardware, and equipment above roadways, driveways,
railroads, and buildings
•
Vertical clearances between telecommunications cables and other utilities (e.g., power,
CATV, other low-voltage signaling)
•
Horizontal clearances between poles, stubs, anchors and guys, and conflicting plants
OSP Design Reference Manual, 4th edition
5-120
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Clearances, continued
Attachment Clearances
Table 5.27 lists typical attachment clearances.
Table 5.27
Typical attachment clearances
Description
Vertical Clearance
Grounded metal sheath power cables, nonmetallic
sheath power cables on grounded support strand,
and power cables consisting of insulated conductors
lashed to or spiraled around a grounded strand
1000 mm (40 in)*
Open supply conductors
to 8.7 kV
8.7 to 50 kV
1020 mm (40 in)
1020 mm (40 in) plus 10 mm (0.4 in)
per kV over 8.7 kV
Drip loops for luminaries or traffic signal brackets
305 mm (12 in)
Grounded supply equipment (e.g., transformers)
762 mm (30 in)
*
May be reduced to 760 mm (30 in) for supply neutrals meeting Rule 230E1 and cables
meeting Rule 230C1. See NESC for details.
in
kV
mm
=
=
=
Inch
Kilovolt
Millimeter
© 2007 BICSI®
5-121
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Clearances, continued
Midspan Clearances
Since the aerial support strand is strung between poles with a specified tension, the addition of
the cable’s weight produces sag. The lowest point of this sag is termed the midspan
because of its centralized location between two poles. Midspan clearances should be at least
75 percent of the clearance required at the pole. Consult the applicable codes, standards,
and regulations for specific details. Vertical clearances between telecommunications cables
and other utilities (e.g., power, CATV, other low-voltage signaling) should be checked at
midspan clearances (see Figure 5.46).
Figure 5.46
Midspan clearances
Power
Telephone
Midspan
clearance
Midspan
clearance
CATV
CATV = Community antenna television
OSP Design Reference Manual, 4th edition
5-122
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Clearances, continued
Vertical Clearances
Both attachment clearances and midspan clearances must meet minimum height requirements
of the AHJ (e.g., Part 2 of the NESC 2007 requirements) for vertical clearances over:
•
Sidewalks.
•
Driveways, parking lots, and alleys.
•
Railroad tracks.
•
Roads, streets, and other areas subject to truck traffic.
•
Roofs accessible to vehicular and truck traffic.
•
Balconies and roofs accessible to pedestrians only.
•
Water areas not subject to sailboat traffic.
•
Sailboat rigging and launching areas, serving water areas.
•
Rural roads.
Consult Figures 5.47 and 5.48 and Tables 5.28 and 5.29 for vertical clearance requirements.
Figure 5.47
Vertical clearances over obstacles
Vertical
clearance
Vertical clearance
Roadway
© 2007 BICSI®
Vertical clearance
Driveway
5-123
Building
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Clearances, continued
Figure 5.48
Vertical clearances between utilities
Power
Vertical
clearance
CATV
Telephone
Vertical
clearance
CATV = Community antenna television
OSP Design Reference Manual, 4th edition
5-124
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Clearances, continued
Table 5.28
Minimum vertical clearances of cables above ground or rails at midspan crossing
Span
Length
m (ft)
Public Streets,
Roads, or Alleys
m (ft)
Alleys
Driveways
m (ft)
Residence
Pedestrians
not Meeting
m (ft)
Ways for
Tracks
Only
m (ft)
Railroad
m (ft)
107 (350)
5.5 (18)
3 (10)
3 (10)
2.4 (8)
7.6 (25)
122 (400)
5.64 (18.5)
4.72 (15.5)
3.2 (10.5)
2.6 (8.5)
7.9 (25.8)
137 (450)
5.8 (19)
5.0 (16.0)
3.4 (11.0)
2.74 (9.0)
8.1 (26.5)
152 (500)
5.94 (19.5)
5.1 (16.5)
3.5 (11.5)
2.9 (9.5)
8.3 (27.3)
168 (550)
6 (20.0)
5.2 (17)
3.7 (12)
3 (10)
8.5 (28)
183 (600)
6.25 (20.5)
5.3 (17.4)
3.8 (12.5)
3.2 (10.5)
8.8 (28.8)
ft = Foot
M = Meter
NOTE: Based on 15 °C (60 °F), no wind, and initial stringing sag.
Table 5.29
Minimum vertical clearance of cable runs along and within limits of public highways
Span
Length
m (ft)
Urban Streets
m (ft)
Alleys
m (ft)
Ways for
Pedestrians Only
m (ft)
Rural Roads
m (ft)
107 (350)
5.5 (18)
3 (10)
2.4 (8)
4.3 (14.0)
122 (400)
5.64 (18.5)
4.72 (15.5)
2.6 (8.5)
4.42 (14.5)
137 (450)
5.8 (19)
5 (16)
2.74 (9.0)
4.6 (15.0)
152 (500)
5.94 (19.5)
5.1 (16.5)
2.9 (9.5)
4.72 (15.5)
168 (550)
6 (20.0)
5.2 (17)
3 (10)
5 (16)
183 (600)
6.2 (20.5)
5.3 (17.4)
3.2 (10.5)
5.1 (16.5)
ft = Foot
M = Meter
NOTE: Based on 15 °C (60 °F), no wind, and initial stringing sag.
© 2007 BICSI®
5-125
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Clearances, continued
Facility Clearances (Government)
When federal, state, city, or county requirements differ, adhere to the more stringent
requirements.
Radial Clearances
A 1.4 m (4.5 ft) horizontal and a 3.2 m (10.5 ft) vertical clearance (see Figure 5.49) should be
maintained from:
•
Antennas.
•
Signs.
•
Pole structures.
•
Storage tanks.
•
Chimneys.
Figure 5.49
Clearance distances
Minimum 0.91 m (3 ft)
radius
Sign
ft = Foot
m = Meter
OSP Design Reference Manual, 4th edition
5-126
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Support Strands
Select support strands based on:
•
Cable weights.
•
Number of cables.
•
Storm loading.
•
Tensile strength.
•
Pole spacing.
Based on stringing tension, the designer should plan the pole line not to exceed 60 percent
of the rated breaking strength of the cable support strand. Cable support strands are available
in various classes, depending on the weight of the zinc coating applied to the support strands.
To avoid long-term deterioration, higher rated zinc coatings should be used in highly corrosive
environments such as coastal areas.
Support Strand Size
Strands are available in the sizes shown in Table 5.30. These sizes are applicable to both
support strands and guys.
Table 5.30
Strand sizes
Size
Diameter
Breaking Strength
Weight
6M
7.9 mm (0.312 in)
26.7 kN (6,000 lbf)
0.33 kg/m (0.225 lb/ft)
6.6M
6.4 mm (0.250 in)
29.6 kN (6,650 lbf)
0.18 kg/m (0.121 lb/ft)
10M
9.5 mm (0.375 in)
51.2 kN (11,500 lbf)
0.40 kg/m (0.270 lb/ft)
16M
11.1 mm (0.438 in)
80.1 kN (18,000 lbf)
0.58 kg/m (0.390 lb/ft)
25M
12.7 mm (0.500 in)
111.0 kN (25,000 lbf)
0.76 kg/m (0.510 lb/ft)
in
kN
lbf
mm
=
=
=
=
Inch
Kilonewton
Pound force
Millimeter
As seen in Table 5.30, the maximum span length for cables of the same weight increases as
the size of the support strand increases. However, since each step up produces a larger and
more expensive support strand, caution should be exercised when arbitrarily increasing the
size of the support strand. In OSP construction, 6M and 10M are the most commonly used
cable support strands; 2.2M should not be used to support aerial cable.
© 2007 BICSI®
5-127
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Anchor and Guys
Anchor and Guys Support Strands
Guying and anchors are normally required at the corners and dead ends of pole lines. The size
of the guy is based on the:
•
Type of wire.
•
Size of the strand.
•
Pull on the pole.
This section discusses types and arrangements of guys, methods for measuring corners, and
guy strength calculations, as well as the types holding power, and placement of anchors.
When a load on a pole is supported by a guy, the guy is considered to assume the full
horizontal load, and should have sufficient strength to meet the requirements of the particular
grade of construction being used.
The pole is regarded as a strut. The guy should be designed to prevent transfer of the
horizontal load to the pole. Guying and anchors are normally required at the corners and dead
ends of pole lines.
Anchor and Guy Configuration
When installing multiple strands on a pole line, the designer should design separate guys
and anchors for each strand. One guy may be used when the distance between two strands
is 610 mm (24 in) or less.
Generally, all corner poles should be guyed except when a pole line supporting 6M or 6.6M
has less than 914 mm (36 in) of pull, or when a pole line supporting 10M strand has less than
610 mm (24 in) of pull.
Common Anchor and Guy Configurations
Some of the more common anchor and guy configurations include:
•
Deadend.
•
Unguyed slack span (see Figure 5.43).
•
Push brace (see Figure 5.50).
•
Corner (see Figure 5.51).
•
False deadend (used when changing strand size).
•
Sidewalk (see Figure 5.51).
•
Span guy.
OSP Design Reference Manual, 4th edition
5-128
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Anchor and Guys, continued
A push brace (see Figure 5.50) may be used where guys cannot be installed, such as:
•
A corner pole where overhead guys cannot be installed.
•
Where terrain makes guying ineffective.
Figure 5.50
Push brace
Push brace
Cable
Push brace
Street
Plan view
Grade
Anchor planks
Push brace
Street
Elevation
view
© 2007 BICSI®
5-129
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Anchor and Guys, continued
Guy Attachment Hardware
After selecting the cable support strand, the appropriate attachment hardware must be
selected.
Three common guying configurations (see Figure 5.51) are:
•
Deadend, a type of attachment used at the end of a cable run or when the pull on a corner
exceeds 15 m (50 ft). If a pull exceeds 15 m (50 ft), a double deadend is required.
•
Tangent, a type of attachment used at an in-line pole.
•
Corner or pull, a type of attachment used to fasten cables at a corner.
Figure 5.51
Guying configurations
Wall/fence
Deadend guy
Cul-de-sac
Sidewalk
guy
Cable
Deadend
guy
Holder
(Galvanized
iron pipe)
Corner guy
Sidewalk guy
Anchor
Plan view
Wall/fence
Sidewalk
Cul-de-sac
Corner guy
Anchor
OSP Design Reference Manual, 4th edition
5-130
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Anchor and Guys, continued
Storm Guying
The amount of storm guying in any line will depend upon the expected severity of individual
storms in the particular area and the amount of exposure to such storms on any section of the
line. Generally, only those sections of a pole line needing to be storm guyed are those that are
greater than 1.6 km (1 mi) in length and where no head guys appear. Two-way storm guys
should be placed at about 1.k km (l mi) intervals, and four-way storm guys at about 3 km
(2 mi) intervals in those sections of line requiring storm guys. Storm guying is illustrated in
Figures 5.52.
Figure 5.52
Storm guying
© 2007 BICSI®
5-131
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Anchor and Guys, continued
Lead-to-Height Ratio
Measured in meters or feet, lead-to-height ratio is equal to the lead divided by the height of the
attachment (see Figure 5.53).
Lead is the horizontal distance from the base of the pole to the anchor rod. Height is the
vertical distance from the ground line to the point of guy attachment on the pole. See
Table 5.32 for maximum allowable tension for guys.
Measured in meters or feet, lead-to-height ratio is equal to the lead divided by the height of the
pole.
Example: If the pole height is 9 m (30 ft) and the lead is 4.6 m (15 ft), then the ratio is equal to
15/30 = 1/2. If the lead is increased to 6 m (20 ft), the ratio is equal to 20/30 = 2/3.
If the lead is increased to 7.6 m (25 ft), the ratio is equal to 25/30 = 5/6. As a rule of
thumb, if the ratio is 3/4 or greater, the strand size for the guy can be the same as
that of the strand. If the ratio is between 1/2 and 3/4, and only two or three spans
are involved, use the next larger cable size for the guy.
Example: A cable is being placed on a 9 m (30 ft) power pole. The point of attachment for the
strand is 6 m (20 ft) above the ground. As a rule of thumb, the lead would be listed
as 4.6 m (15 ft). The lead-to-height ratio is 3/4.
Figure 5.53
Definition of lead and height
Height
Height
Lead
Height
Height
Lead
Lead
Lead
n
ai
rr
ng
Te
i
op
Sl
Height
Lead
Lead
(L)
Height
(H)
Height (H)
Guy attachment
Pipe
Sidewalk
Description of lead and height
OSP Design Reference Manual, 4th edition
Sidewalk anchor guy
5-132
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Anchor and Guys, continued
Measuring the Corner Pull
The pull on a pole can be calculated using one of three methods. These include using a pull
finder, using a tape measure, and measuring the included angle created by the three points.
The pull is a vectorizing method used to estimate the required strand size for guying (see
Figure 5.55)
A pull finder is a method used by many companies (see Figure 5.54). To use a
pull finder:
1. Screw the threaded end of the pull finder into a pole.
2. Sight down each sight to the next pole in the line (proposed or existing).
3. Read the pull off the scale.
Figure 5.54
Calculating pull with pull finder
16 mm (5/8 in)
2
Screw
thread
Front
sight
R
od
5
M
M
.6
6 d
M n
0 a
1 tr
S
Rod
Underside view of guy rod
and strand gauge
Front
sight
Back
sight
Index
mark
in = Inch
mm = Millimeter
© 2007 BICSI®
5-133
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Anchor and Guys, continued
As shown in Figure 5.55, the pull may also be calculated by using a tape measure:
•
The lines of the poles adjacent to the corner pole is extended 30.5 m (100 ft) farther;
•
A straight line is established between those points; and,
•
The distance from those lines to the corner pull determines the pull.
Figure 5.55
Calculating pull with tape measure
t)
0f
Corner pole
m
15
15
30
(5
.5
ft)
.5
m
ft)
(1
30
N
Corner pole
(5
0f
t)
Pole
00
Pull
(1
00
Pull
m
m
Pole
Pole
Pole
Corner pole
30.5 m (100 ft)
30.5 m (100 ft)
Pull
Pole
Pole
ft = Foot
m = Meter
OSP Design Reference Manual, 4th edition
5-134
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Anchor and Guys, continued
By calculating the interior angle at the corner pole (see Figure 5.55), the pull may be
determined (see Table 5.31).
Table 5.31
Calculating pull when angle is known
Interior Angle
degree
Pull
m (ft)
180
0 (0)
175
1.34 (4.4)
170
2.66 (8.7)
165
3.98 (13.1)
160
5.3 (17.4)
155
6.58 (21.6)
150
7.89 (25.9)
145
9.17 (30.1)
140
10.41 (34.2)
135
11.7 (38.4)
130
12.9 (42.3)
125
14.10 (46.2)
120
15 (50)
ft
m
© 2007 BICSI®
=
=
Foot
Meter
5-135
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Anchor and Guys, continued
Calculating Guy Strength
The required strength of a guy at any location is calculated by multiplying the actual tension in
the guy by the required safety factor (see Table 5.32). For example, if the actual tension in the
guy at a single comer pole for grade D construction is 3700 pounds (16,458 Newtons), the
required guy strength would be 3700 pounds X 2.67 = 9879 pounds (43,941 Newtons). A 10M
strand with a rated breaking strength of 11,500 pounds (51,152 Newtons) fulfills the
requirement.
Table 5.32
Maximum allowable tension for guys
Grade of Construction
Maximum Allowable Tension for Guys
Percent of Guy
Rated Breaking
Strength
Safety Factor
37.5
2.67
Longitudinal load (head guy at
locations other than dead ends)
100.00
1.00
Longitudinal load at dead ends
66.67
1.50
Grade C
Transverse load
50.0
2.00
Longitudinal load (head guy at
locations other than dead ends)
100.00
1.00
Longitudinal load at dead ends
87.5
1.14
Grade N
Transverse load
100.00
1.00
Longitudinal load
100.00
1.00
Grade D
Transverse load
37.5
2.67
Longitudinal load (head guy at
locations other than dead ends)
100.00
1.00
Longitudinal load at dead ends
66.67
1.50
Grade B
Transverse load
OSP Design Reference Manual, 4th edition
5-136
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Anchor and Guys, continued
Guy Size
Deadends and corners in pole lines usually require guying to support the cable or wire facility.
The size of the guy is based on the size of the suspension strand or type of wire, the lead and
height of the guy, and the pull on the pole (see Table 5.33), as follows:
•
If the lead-to-height ratio is 3/4 or greater, head guys for cables can be the same size as
the suspension strand.
•
If the lead-to-height ratio is between 1/2 and 3/4 and only two or three spans are involved,
head guys for cables should be one size larger than the suspension strand.
•
For all other guys, the guy rule should be used to determine guy size (see Figure 5.56).
Where 6M guy is indicated, 6.6M guy may be used.
•
At corner poles, a pull finder should be used to determine the pull on a pole.
•
If the pull on a corner pole is less than 15 m (50 ft), a guy can be placed at a bisecting
angle.
•
If the pull is greater than a 45 degree angle, two head guys are required, an arrangement
known as double deadend.
Table 5.33
Minimum guy strand selection table
Filled Copper or Optical Fiber Cable Corner
Heavy, Medium, and Light Loading Districts
Suspension
Strand Size
6M
10M
16M
20M
Lead-to-Height
Ratio
Corner Angles (Degrees)
5
10
15
20
25
30
35
40
45
1/2
6M
6M
6M
6M
6M
6M
10M
10M
10M
1
6M
6M
6M
6M
6M
6M
6M
6M
6M
1/2
6M
6M
6M
6M
10M
10M
10M
16M
16M
1
6M
6M
6M
6M
6M
6M
6M
10M
10M
1/2
6M
6M
10M 10M
10M
16M 16M
20M
20M
1
6M
6M
6M
10M
10M
10M
6M
16M
1/2
6M
6M
10M 10M
16M
16M
20M
26M
26M
1
6M
6M
6M
10M
10M
16M
16M
16M
6M
6M
NOTES: For 20M guy size, two 10M guys or equivalents should be used.
For 26M guy size, one 10M guy and one 16M guy or equivalents should be used.
For 32M guy size, two 16M guys or equivalents should be used.
© 2007 BICSI®
5-137
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Anchor and Guys, continued
Figure 5.56
Guy rule
OSP Design Reference Manual, 4th edition
5-138
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Anchor and Guys, continued
Table 5.34 lists maximum corner angle for filled self-supporting optical fiber cable. The corner
angle and the interior angle must add to 180 degrees. Figure 5.57 shows an example using the
information in the guy strand selection table.
Table 5.34
Guy strand selection table
Filled, Self-Supporting Optical Fiber Cables
Integral Support L/H
Strand Size
Ratio
63 mm (0.25 in)
Maximum Corner Angle in Degrees
for Size of Guy Strand
6M
10M
1/2
35
60
1
60
60
in = Inch
m m = Millimeter
Figure 5.57
Using guy strand selection chart example
10M
10M
Height
6 m (20 ft)
20
Lead
6 m (20 ft)
ft = Foot
m = Meter
For the above example:
L/H = 20/20 = 1
Support strand = 10M
∠ = 20°
Then, from Table 5.33, the guy strand should be 6M.
© 2007 BICSI®
5-139
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Anchor and Guys, continued
Anchors
Existing field conditions determine the type of anchor to be used (see Figure 5.58). Types of
anchors include:
•
Expansion anchor.
•
Screw anchor.
•
Plate anchor.
•
Plank anchor.
•
Pole-to-pole anchor.
•
Rock anchor.
•
Log anchor.
•
Stub and anchor.
•
Swamp anchors.
Figure 5.58
Types of common anchors
Rod
Closed
Open
Expansion anchor
Slot cut for
anchor rod
Anchor
rod
Screw anchor
Length as
required
Nut
Square washer
Plate anchor
Pipe anchor rod
Screw plate
Coupling
Pipe eye nut
Swap anchor
Cross piece
set in recess
OSP Design Reference Manual, 4th edition
5-140
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Anchor and Guys, continued
Soil Classifications
Soils are classified according to type, condition, and moisture content, as follows:
•
Class 1—Hard rock, solid.
•
Class 2—Shale, sandstone, solid, or in adjacent layers.
•
Class 3—Hard dry, hardpan. Requires use of digging bar.
•
Class 4—Crumbly, damp. This class contains mostly clay, is not moist enough to pack into
a ball when squeezed by hand, and has particles that crumble off.
•
Class 5—Firm, moist. This class contains mostly clay which, when squeezed by hand,
forms into a firm ball. Moist soils in well-drained areas are in this class.
•
Class 6—Plastic, wet. This class contains mostly clay and is usually found in fairly flat
terrain. When squeezed by hand, it readily assumes any shape.
•
Class 7a—Loose, dry. This class is found in arid regions and contains mostly sand and
gravel. Filled- in or built-up areas in dry regions are in this class.
•
Class 7b—Loose, wet. This class has the same holding ability as class 7a and is high in
sand, gravel, or loam content; however, its holding ability decreases during rainy seasons.
This class of soil is usually found in poorly drained areas.
•
Class 8—Swamps and marshes. This class includes areas where the soils are marshy
only seasonally. Moist soils will vary in their classification during the year because of
changes in moisture content. Extreme conditions should be estimated.
The holding ability of an anchor is determined by the type and size of the anchor and the soil
conditions. Moisture content and its effect on soil is a greater factor in deciding ultimate soilanchor holding strengths than factors based on fine divisions of soil content. The ultimate soilanchor holding strength is reached at the point where the anchor will start pulling out in a
particular soil when placed at a 45-degree angle and the anchors set to a specified depth of
rod length, less 152 mm (6 in). The groups are listed in Table 5.35.
© 2007 BICSI®
5-141
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Anchor and Guys, continued
Table 5.35
Anchor groupings
Group
Type
Anchor
1
Screw
Cone
152 mm (6 in)
152 mm (6 in)
2
Screw
Cone
Expanding
203 mm (8 in)
203 mm (8 in)
152 mm (6 in), 2 way
3
Screw
Cone
Expanding
Expanding
254 mm (10 in), 1.7 m rod (5 -1/2 ft rod)
254 mm (10 in)
152 mm (6 in), 4 way
152 mm (6 in), 8 way, 45161 mm2 (70 in2) area
4
Screw
Cone
Expanding
Expanding
Plate
Log
254 mm (10 in), 1.7 m rod (8 ft rod)
305 mm (12 in)
203 mm (8 in), 2 way
203 mm (8 in), 3 way
152 mm (6 in) x 432 mm (17 in)
1 m x 178 mm (3 ft x 7 in)
5
Expanding
Expanding
Plate
Plate
Log
203 mm (8 in), 4 way
203 mm (8 in), 8 way
152 mm x 559 mm (6 in x 22 in)
406 mm (16 in) crossplate
1.2 m x 203 mm (4 ft x 8 in)
6
Cone
Expanding
Expanding
Plate
406 mm (16 in)
254 mm (10 in), 4 way
254 mm (10 in), 8 way
508 mm (20 in) crossplate
7
Cone
Plate
Plate
483 mm (19 in)
203 mm x 686 mm (8 in x 27 in)
508 mm (20 in) crossplate
8
Cone
Expanding
Plate
Plate
Log
584 mm (23 in)
305 mm (12 in), 4 way
203 mm x 889 mm (8 in x 35 in)
610 mm (24 in) crossplate
1.52 m x 254 mm (5 ft x 10 in)
9
Plate
Log
2.54 mm x 1016 mm (10 in x 40 in)
1.83 m x 254 mm (6 ft x 10 in)
10
Log
2.1 m x 305 mm (7 ft x 12 in)
11
Log
2.4 m x 305 mm (8 ft x 12 in)
ft
in
m
mm
=
=
=
=
Foot
Inch
Meter
Millimeter
OSP Design Reference Manual, 4th edition
5-142
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Anchor and Guys, continued
Guy Rod Size
Three main rod sizes are:
•
12M—9.5 mm (3/8 in) diameter.
•
18M—19 mm (3/4 in) diameter.
•
32M—32 mm (1-1/4 in) diameter.
These ratings indicate the maximum capacity of the rod. For example, an 18M (3/4 in)
diameter rod can accept three 6M guys, one 10M and one 6M, or one 16M guy.
Guy Rod Ends
Based on the number of guys to be attached, the designer must size the rod end
(see Figure 5.59) as:
© 2007 BICSI®
•
Single thimble eye.
•
Double thimble eye.
•
Triple thimble eye.
•
Loop
5-143
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Anchor and Guys, continued
Figure 5.59
Guy rod ends
For aerial construction, facility ownership may be determined based on poles and pole
markings. For new pole, underground, and buried installation, the designer will work with
the AHJ and locate subsurface utilities.
OSP Design Reference Manual, 4th edition
5-144
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Anchor and Guys, continued
Selection of Anchors
The selection of the specific anchor within each group must be based upon the soil
classification, since some anchors are not suitable for all soil classes. The groupings are
arranged with the smallest anchors in the lowest numerical order. Group selection is made
using table 4.5, considering soil conditions and the holding power required.
The designer should first establish the soil classification for the particular area and then
establish the group of anchors most suitable for that condition. This procedure simplifies
supply and installation problems by eliminating unnecessary tools and unsuitable anchor types
(see Table 5..
Type Selection
Anchors within a specific group size may be used interchangeably at a guy location, provided
they are suitable for the particular soil. If no anchor in the specified group size is available, an
anchor from a numerically higher group size may be selected. If the available anchors in the
specified size group would be difficult to install, a suitable type of anchor may be selected
from another higher group size. Anchors from lower numbered group sizes than the group
specified for a specific guy location should not be used.
Anchor type selection is based on the adaptability of the anchor to the particular soil class; for
example, a cone anchor is not adaptable to loose soils. The equipment available for digging the
anchor hole will also help to determine the type of anchor to be used. Table 5.36 lists the types
of anchors recommended for installation in the different soil classes.
© 2007 BICSI®
5-145
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Anchor and Guys, continued
Table 5.36
Soil classifications
Class
Common Soil-Type
Description
Geological Soil
Classification
Probe
Values
in-lb
(N/m)
N/A
Typical Blow
Count “N”
Per
ASTM-D1586
0
Sound hard rock,
unweathered
Granite, basalt,
massive limestone
N/A
1
Very dense or cemented
sands; coarse gravel
and cobbles
Caliche (nitrate-bearing
gravel/rock)
750-1600
(85-181)
60-100+
2
Dense fine sands; very
hard silts and clays
(may be preloaded)
Basal till; boulder clay;
caliche; weathered
laminated rock
600-750
(68-85)
45-60
3
Dense sands and gravel;
hard silts and clays
Glacial till; weathered
shales, schist, gneiss
and siltstone
500-600
(56-68)
35-50
4
Medium dense sand and
gravel; very stiff to hard
silts and clays
Glacial till; hardpan; marls
400-500
(45-56)
24-40
5
Medium dense coarse
sands and sandy gravels;
stiff to very stiff silts
and clays
Saprolites, residual soils
300-400
(34-45)
14-25
6
Loose to medium dense
fine to coarse sands to
stiff clays and silts
Dense hydraulic fill;
compacted fill;
residual soils
200-300
(23-34)
7-14
*7
Loose fine sands; alluvium;
loess; medium-stiff and
varied clays; fill
Flood plain soils,
lake clays; adobe;
gumbo, fill
100-200
(11-23)
4-8
*8
Peat, organic silts;
inundated silts, fly ash
very loose sands, very
soft to soft clays
Miscellaneous fill,
swamp marsh
Less than 100
(0-11)
0-5
NOTE:
*
Class 1 soils are difficult to probe consistently and the ASTM blow count may be of
questionable value.
It is advisable to install anchors deep enough, by the use of extensions, to penetrate a
Class 5 or 6, underlying the Class 7 or 8 soils.
ASTM®
in
lb
N/A
N/m
=
=
=
=
=
American Society for Testing and Materials
Inch
Pound
Not applicable
Newton per meter
OSP Design Reference Manual, 4th edition
5-146
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Anchor and Guys, continued
Select your anchor type in accordance with the soil classification as shown in
Table 5.37.
Table 5.37
Anchor types recommended for different soil classes
© 2007 BICSI®
Soil Class
Recommended Anchor Type
1 Solid rock
Expanding rock
2 Layered rock
Cone
Log
3 Hardpan
Crossplate or plank
Plate
Cone
Expanding
Log
4 Crumbly, damp
Crossplate or plank
Plate
Cone
Expanding
Log
Screw
5 Firm, moist
Crossplate or plank
Plate
Screw
Expanding
Log
6 Plastic, wet
Crossplate or plank
Plate
Screw
Expanding
Log
7 Loose, wet, or dry
Screw
Expanding
Crossplate or plank
LogPlate
8 Swamp
Swamp screw
Log
5-147
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Anchor and Guys, continued
Location and Installation of Anchors
Location
Safety, appearance, and economy should be considered when locating guy anchors. Anchors
should be kept away from locations where they would be subject to mechanical damage (e.g.,
curbs and roads) and where they could cause personal injury (e.g., sidewalks and building
entrances).
Installation
Earth augers are used to dig holes for anchors wherever practicable. Anchors should be
placed with the anchor rod as nearly in line as possible with the point of attachment of the guy
to the pole, and the rod should be turned to face the eye properly. After the anchor is placed,
the anchor hole should be filled and tamped. Soil should be heaped and packed around the rod.
The anchor rod should not be exposed more than 152 mm (6 in) above the ground, with the
eye of the anchor rod left clear .Log anchors require square or curved washers at least
101 mm (4 in) across connected to the end of the anchor rod to prevent the rod from pulling
through the log.
OSP Design Reference Manual, 4th edition
5-148
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Designing Additions to Existing Aerial Support Structures
Pole Line Adequacy
A preexisting pole line must be capable of supporting the proposed cables. To determine its
adequacy, poles along the proposed route should be physically inspected and their loading
capabilities should be determined.
When physically inspecting the poles, the designer should verify the:
•
Pole’s physical integrity. The designer should check if the poles are bent, split, or rotted.
Probing sections of the pole below the ground line with a pole prod will help detect
nonvisible, rotted areas.
•
Presence of guys or anchors. If guys and anchors are missing, the designer should verify
that there is sufficient room to place new ones. A line may need additional guying before
the addition of the proposed cables to prevent unbalanced loads.
•
Existence of a grounding (earthing) system.
•
Existing cable/equipment on the poles.
•
Proper clearances from other utilities.
•
Obstructions.
•
Height of pole.
•
Class of pole.
•
Age of pole.
•
Pole composition.
•
Owner.
•
Joint use.
Pole Line Construction Classification
Referring to Table 5.34, the designer should determine which grade of construction applies to
the existing pole line.
The voltages listed in this table are phase-to-ground values for:
• Effectively grounded alternating current (ac) circuits.
• Two-wire grounded circuits.
• Center-grounded dc circuits.
In other instances, phase-to-phase values shall be used. The grade of construction for supply
conductors, as indicated in Table 5.38, shall also meet the requirements for any lines at lower
levels except when otherwise noted.
NOTE:
© 2007 BICSI®
Placing of telecommunications conductors at higher levels at crossing or on jointly
used poles should generally be avoided, unless the supply conductors are trolley
contact conductors and their associated feeders.
5-149
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Designing Additions to Existing Aerial Support Structures, continued
Table 5.38
Grades of construction for communications conductors
Communication Conductors
(Communication Conductors, Rural or
Urban, Open or Cable, Including Those
Run in the Supply Space)
Conductors, Tracks,
and Rights-of-Way
at Lower Levels
Exclusive private right-of-way
N
Common or public rights-of-way
N
Railroad tracks and limited-access highways1
B
Constant-potential supply conductors2
0 to 750 V
Open or cable
750 V to 2.9 kV
Open or cable
Exceeding 2.9 kV
Open
Cable
N
C
B
C
Constant-current supply conductor2
0 to 7.5 A
Open3
Exceeding 7.5 A
Open3
C
Communications conductors, open or cable, urban
or rural including those run in the supply space
B, C, or N
B4
1
2
There is no intent to require Grade B over ordinary streets and highways.
The words open and cable appearing in the headlines have the following meaning as
applied to supply conductors: Cable means Type 1 cables as described in Rule 241A1; open
means open-wire and also Type 2 cables, as described in Rule 241A2.
3
Where constant-current circuits are in Type 1 cable, the grade of construction shall be
based on the nominal full-load voltage.
4
Grade C construction may be used if the open-circuit voltage of the transformer supplying
the circuit does not exceed 2.9 kV.
A = Ampere
k V = Kilovolt
OSP Design Reference Manual, 4th edition
5-150
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Designing Additions to Existing Aerial Support Structures, continued
System Plans
A designer should be aware of any existing future system plans for an existing pole line.
These may include regional road move plans or any future plans for the additions of cable.
Joint-Use Agreements
If the existing pole line is owned by another utility or municipality, the designer must verify the
existence of a joint-use agreement and submit the proper documentation to the utility in order
to obtain permission to attach. Approval can be as simple as providing the utility with a set of
construction drawings or as complicated as negotiating a joint-use agreement and rental fees
for the use of the pole space.
Makeready Work
Joint use of an existing utility pole line still requires maintaining all separations between utilities,
structures, and elevations above ground for streets, sidewalks, railroads, and other ground
clearances (see Tables 5.27, 5.28, and 5.29). Agreements must be negotiated to inspect and
move existing utilities (e.g., install taller poles and then transfer and respace utilities) to provide
necessary clearances. This can be a lengthy and expensive process.
NOTE:
Refer to Chapter 13: Special Design Considerations for further information.
Design Transition Structures
Examples of design transition structures include:
© 2007 BICSI®
•
Aerial to underground (see Figure 5.60).
•
Aerial to direct-buried (see Figure 5.61).
•
Aerial to tunnel.
•
Underground to direct-buried (see Figure 5.62).
•
Underground to tunnel.
•
Underground to building (see Figure 5.63).
•
Aerial to building (see Figure 5.64).
•
Direct-buried to building (see Figure 5.65).
•
Tunnel to building.
5-151
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Design Transition Structures, continued
Figure 5.60
Aerial to underground transition
Splice case
Aerial cable
Lateral cable
Pole
Conduit or
cable guard
Lateral cable
Splice case
Subsidiary conduit
Conduit
Conduit
Underground cable
Maintenance hole
Figure 5.61
Aerial to direct-buried transition
Splice case
Aerial cable
Conduit or cable guard
Pole
Pedestal/splice closure
Lateral cable
Buried cable
OSP Design Reference Manual, 4th edition
5-152
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Design Transition Structures, continued
Figure 5.62
Underground to direct-buried transition
Pedestal/splice closure
Buried cable
Subsidiary conduit
Buried cable
Conduit
Conduit
Underground cable
Splice case
Maintenance hole
Figure 5.63
Underground to building transition
Building
Backboard
Protector
Cable
Splice
case
Conduit
Underground
cable
© 2007 BICSI®
Subsidiary
conduit
Conduit
Maintenance hole
5-153
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 3: Aerial Pathways
Design Transition Structures, continued
Figure 5.64
Aerial to building transition
Support strand to building
Aerial cable
Splice case
Terminal
protector
Sleeve through
building wall
Aerial
cable
Backboard
Protector
OSP Design Reference Manual, 4th edition
5-154
© 2007 BICSI®
Section 3: Aerial Pathways
Chapter 5: Pathways and Spaces
Design Transition Structures, continued
Figure 5.65
Direct-buried to building transition
Terminal protector
Pedestal/splice closure
Grade
Sleeve
Direct-buried cable
Protector
Backboard
Sleeve through
building wall
Cable
Pedestal/splice closure
Grade
Direct-buried cable
© 2007 BICSI®
5-155
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
OSP Design Reference Manual, 4th edition
Section 3: Aerial Pathways
5-156
© 2007 BICSI®
Section 4: Aerial Construction Practices
Chapter 5: Pathways and Spaces
Placement
Depth of Pole Setting
General
The depth of setting will vary according to the:
•
Pole length.
•
Type of soil.
•
Number and type of attachments on the pole.
The nature of the soil should be established during the initial field survey so that proper
recommendations for setting depth and necessary special tools may be indicated on the
construction work prints.
© 2007 BICSI®
5-157
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 4: Aerial Construction Practices
Depth of Pole Setting, continued
Firm Soil or Solid Rock
Table 5.39 lists standard depths for setting poles in average firm soil or in solid or layered
rock.
Table 5.39
Standard pole settings
Length of
Pole
m (ft)
Depth of Setting In
Average Firm Soil
m (ft)
Depth of Setting
in Solid Rock
m (ft*)
4.9 (16)
1.1 (3.5)
0.9 (3.0)
5.5 (18)
1.1 (3.5)
0.9 (3.0)
6.0 (20)
1.2 (4.0)
0.9 (3.0)
6.7 (22)
1.2 (4.0)
0.9 (3.0)
7.6 (25)
1.5 (5.0)
0.9 (3.0)
9.0 (30)
1.7 (5.5)
1.1 (3.5)
10.4 (35)
1.8 (6.0)
1.2 (4.0)
12.0 (40)
1.8 (6.0)
1.2 (4.0)
13.7 (45)
2.0 (6.5)
1.4 (4.5)
15.0 (50)
2.1 (7.0)
1.4 (4.5)
16.8 (55)
2.3 (7.5)
1.5 (5.0)
18.3 (60)
2.4 (8.0)
1.5 (5.0)
19.8 (65)
2.6 (8.5)
1.8 (6.0)
21.3 (70)
2.7 (9.0)
1.8 (6.0)
23.0 (75)
2.9 (9.5)
1.8 (6.0)
24.0 (80)
3.0 (10.0)
2.1 (7.0)
26.0 (85)
3.2 (10.5)
2.1 (7.0)
27.4 (90)
3.4 (11.0)
2.1 (7.0)
*These depths are recommended where solid rock is encountered at ground level and the
diameter of the hole is such as to permit pieces of rock to be tamped firmly between the pole
surface and hole walls to prevent the pole from leaning.
ft = Foot
m = Meter
OSP Design Reference Manual, 4th edition
5-158
© 2007 BICSI®
Section 4: Aerial Construction Practices
Chapter 5: Pathways and Spaces
Depth of Pole Setting, continued
Soil and Rock
Table 5.40 lists the standard pole hole depths for setting poles in soils where solid or layered
rock is found below the surface level.
Table 5.40
Pole settings for solid rock below surface level
Depth Below
Surface at Which 6.1
Solid Rock is
(20)
7.6
(25)
9.1
(30)
Found in m (ft)
10.7
(35)
Pole Length in m (ft)
12.2
13.7
15.2
(40)
(45)
(50)
16.8
(55)
18.3
(60)
21.3
(70)
24.4
(80)
27.4
(90)
Minimum Hole Depth in m (ft)
0.0
(0.0)
0.9
(3.0)
0.9
(3.0)
1.1
(3.5)
1.2
(4.0)
1.2
(4.0)
1.4
(4.5)
1.4
(4.5)
1.5
(5.0)
1.5
(5.0)
1.8
(6.0)
2.1
(7.0)
2.1
(7.0)
0.2
(0.5)
1.1
(3.5)
1.1
(3.5)
1.2
(4.0)
1.4
(4.5)
1.4
(4.5)
1.7
(5.5)
1.7
(5.5)
1.8
(6.0)
1.8
(6.0)
2
(6.5)
2.3
(7.5)
2.3
(7.5)
0.3
(1.0)
1.2
(4.0)
1.2
(4.0)
1.4
(4.5)
1.5
(5.0)
1.5
(5.0)
1.7
(5.5)
1.7
(5.5)
1.8
(6.0)
1.8
(6.0)
2.1
(7.0)
2.4
(8.0)
2.4
(8.0)
0.5
(1.5)
1.2
(4.0)
1.4
(4.5)
1.2
(4.0)
1.7
(5.5)
1.7
(5.5)
1.8
(6.0)
1.8
(6.0)
2
(6.5)
2
(6.5)
2.3
(7.5)
2.6
(8.5)
2.6
(8.5)
0.6
(2.0)
1.5
(5.0)
1.5
(5.0)
1.7
(5.5)
1.8
(6.0)
1.8
(6.0)
2
(6.5)
2
(6.5)
2.1
(7.0)
2.1
(7.0)
2.4
(8.0)
2.7
(9.0)
2.7
(9.0)
0.8
(2.5)
1.2
(4.0)
1.5
(5.0)
1.7
(5.5)
1.8
(6.0)
1.8
(6.0)
2
(6.5)
2.1
(7.0)
2.3
(7.5)
2.3
(7.5)
2.6
(8.5)
2.9
(9.5)
2.9
(9.5)
0.9
(3.0)
1.2
(4.0)
1.5
(5.0)
1.7
(5.5)
1.8
(6.0)
1.8
(6.0)
2
(6.5)
2.1
(7.0)
2.3
(7.5)
2.4
(8.0)
2.7
(9.0)
2.9
3
(9.5) (10.0)
1.1
(3.5)
1.2
(4.0)
1.5
(5.0)
1.7
(5.5)
1.8
(6.0)
1.8
(6.0)
2
(6.5)
2.1
(7.0)
2.3
(7.5)
2.4
(8.0)
2.7
3
3.2
(9.0) (10.0) (10.5)
1.2
(4.0)
1.2
(4.0)
1.5
(5.0)
1.7
(5.5)
1.8
(6.0)
1.8
(6.0)
2
(6.5)
2.1
(7.0)
2.3
(7.5)
2.4
(8.0)
2.7
3
3.4
(9.0) (10.0) (11.0)
1.4
(4.5)
–
–
1.5
(5.0)
1.7
(5.5)
1.8
(6.0)
1.8
(6.0)
2
(6.5)
2.1
(7.0)
2.3
(7.5)
2.4
(8.0)
2.7
3
3.4
(9.0) (10.0) (11.0)
1.5
(5.0)
–
–
1.5
(5.0)
1.7
(5.5)
1.8
(6.0)
1.8
(6.0)
2
(6.5)
2.1
(7.0)
2.3
(7.5)
2.4
(8.0)
2.7
3
3.4
(9.0) (10.0) (11.0)
1.7
(5.5)
–
–
–
–
1.7
(5.5)
1.8
(6.0)
1.8
(6.0)
2
(6.5)
2.1
(7.0)
2.3
(7.5)
2.4
(8.0)
2.7
3
3.4
(9.0) (10.0) (11.0)
© 2007 BICSI®
5-159
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 4: Aerial Construction Practices
Depth of Pole Setting, continued
Table 5.40
Pole settings for solid rock below surface level, continued
Depth Below
Surface at Which 6.1
Solid Rock is
(20)
7.6
(25)
9.1
(30)
Pole Length in m (ft)
12.2
13.7
15.2
(40)
(45)
(50)
10.7
(35)
found in m (ft)
16.8
(55)
18.3
(60)
21.3
(70)
24.4
(80)
27.4
(90)
Minimum Hole Depth in m (ft)
1.8
(6.0)
–
–
–
–
–
–
1.8
(6.0)
1.8
(6.0)
2
(6.5)
2.1
(7.0)
2.3
(7.5)
2.4
(8.0)
2.7
(9.0)
3
3.4
(10.0) (11.0)
2
(6.5)
–
–
–
–
–
–
–
–
–
–
2
(6.5)
2.1
(7.0)
2.3
(7.5)
2.4
(8.0)
2.7
(9.0)
3
3.4
(10.0) (11.0)
2.1
(7.0)
–
–
–
–
–
–
–
–
–
–
–
–
2.1
(7.0)
2.4
(8.0)
2.4
(8.0)
3
3.4
3.4
(10.0) (11.0) (11.0)
2.3
(7.5)
–
–
–
–
–
–
–
–
–
–
–
–
–
–
2.3
(7.5)
2.4
(8.0)
2.7
(9.0)
3
–
(10.0) –
2.4
(8.0)
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
2.4
(8.0)
2.7
(9.0)
3
3.4
(10.0) (11.0)
2.7
(9.0)
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
2.7
(9.0)
3
3.4
(10.0) (11.0)
3
(10.0)
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
3
3.4
(10.0) (11.0)
3.4
(11.0)
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
3.4
(11.0)
ft = Foot
m = Meter
OSP Design Reference Manual, 4th edition
5-160
© 2007 BICSI®
Section 4: Aerial Construction Practices
Chapter 5: Pathways and Spaces
Depth of Pole Setting, continued
Frozen Soil
Permanently frozen soil or permafrost is common in the northernmost parts of North America,
Europe, and Asia. When poles are placed in soils over permafrost, the depth of the pole hole
must be increased; otherwise, the pole may be forced out of the ground or overturned during
refreezing of the soil at the surface level (see Figures 5.66 and 5.67). The depth of seasonal
thaws varies at different locations and depends primarily on the nature of the overlying soil
and the amount of ground water during the refreezing process. When the soil overlying the
permafrost is composed of coarse sand and gravel and is well drained, the soil is classified
as nonactive and the depth of the pole hole does not need to be increased over the standard
setting for poles in average firm soil.
© 2007 BICSI®
5-161
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 4: Aerial Construction Practices
Depth of Pole Setting, continued
Figure 5.66
Typical settings of poles in permafrost
Ground Level
Ground Level
0.6 m
(2 ft)
0.6 m
(2 ft)
0.9 m
(3 ft)
1.5 m
(5 ft)
0.9 m
(3 ft)
2.7 m
(9 ft)
1.2 m
(4 ft)
Permafrost with nonactive layer
Permafrost with active layer
Nonactive layer
Permafrost
Active layer
ft = Foot
m = Meter
OSP Design Reference Manual, 4th edition
5-162
© 2007 BICSI®
Section 4: Aerial Construction Practices
Chapter 5: Pathways and Spaces
Depth of Pole Setting, continued
Figure 5.67
Effect on pole when active layer above permafrost is refrozen
Active Layer Frozen
Active Layer Not Frozen
Active Layer
Ground Water Or Ice
Permafrost
© 2007 BICSI®
5-163
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 4: Aerial Construction Practices
Depth of Pole Setting, continued
When the soil overlaying the permafrost is composed of silt, clay, or humus and contains large
amounts of ground water, the soil is classified as active and the depth of the pole must be
increased. The amount of increase over the depth for setting in average firm soil is equal to
the depth of the active layer of soil multiplied by 2, except that the depth of the portion of the
hole in the permafrost layer (see Figure 5.67) need not exceed that required for a hole in
average firm earth multiplied by 1.5.
EXAMPLE:
A 7.6 meter (m [25 foot (ft)]) pole in average firm soil requires a 1.5 m (5 ft)
depth of setting. If the depth of the active layer of soil were 0.6 m (2 ft), the
total depth of the hole would be 0.6 m (2 ft) plus 0.9 m (3 ft) in average firm
soil requiring a 1.5 m (5 ft) depth of setting.
If the depth of the active layer of soil were 0.6 m (2 ft), the total depth of the
hole would be 0.6 m (2 ft) plus 0.9 m (3 ft) for required depth of setting, plus
1.2 m (4 ft) or twice the active layer of soil, for a total of 2.7 m (9 ft). Since
the 2.1 m (7 ft) depth in the permafrost layer is smaller than the setting in
average firm soil multiplied by the 1.5, no reduction in depth is allowed.
Swampy Soil
When poles are placed in swampy areas or loose soils, the depth of setting could be increased
0.3 m (1 ft) over the values for poles set in average firm soil. This increase in setting is
required only when a soil footing of 0.3 m (1 ft) or 0.6 m (2 ft) will be obtained or a plank
footing for the pole is not placed. It will not be necessary to increase the depth of holes for
poles supported by side guys, ground braces, or swamp fixtures. In extremely swampy soil, a
pole crib should be used.
Sloping Ground
The depth of pole holes in sloping ground is calculated by:
1. Placing a stick horizontally from the upper edge of the hole and measuring the distance A
between the stick and the lower edge of the hole as shown in Figure 5.68.
2. Obtaining the standard hole depth for the pole on the level grade from Tables 5.39 and
5.40, whichever applies.
3. Adding the distance A to the standard setting. The sum obtained is the depth at which the
pole should be set.
OSP Design Reference Manual, 4th edition
5-164
© 2007 BICSI®
Section 4: Aerial Construction Practices
Chapter 5: Pathways and Spaces
Depth of Pole Setting, continued
Figure 5.68
Setting pole in sloping ground
Surface of slope
Stick
“A”
Pole
hole
Depth in
level
ground
plus “A”
Soil
© 2007 BICSI®
5-165
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 4: Aerial Construction Practices
Depth of Pole Setting, continued
River or Stream Bank
When the pole is placed within 1.2 m (4 ft) of a bank, particularly where water is present,
the depth of the hole should be 0.3 m (1 ft) or 0.6 m (2 ft) greater than that required for level
ground. Ground conditions determine the amount of additional depth. Additional depth of
0.6 m (2 ft) is recommended when the soil is continually wet. If the pole location is in danger
of being flooded or is in extremely swampy land, the pole may be placed in a pole crib as
shown in Figure 5.69. The longer side of the crib should be transverse to the line.
Figure 5.69
Typical pole crib
1.83 m (6 ft)
1.2 m x 1.83 m
(4 ft - 6 ft)
ROCKS
Swampland
ft = Foot
m = Meter
OSP Design Reference Manual, 4th edition
5-166
© 2007 BICSI®
Section 4: Aerial Construction Practices
Chapter 5: Pathways and Spaces
Depth of Pole Setting, continued
Unguyed Angles
All unguyed angle poles will be set 0.3 m (1 ft) deeper than the normal depth required for level
ground
Restrictions of Pole Height
The two basic restrictions on pole height are interference with:
•
Safe operation of aircraft.
•
Telecommunications (electronics) equipment (e.g., microwave) locations.
The first restriction is based on the hazard to aircraft when pole lines are constructed on or
near aircraft landing and approach zones. Preferably, overhead construction should not be
used in these areas. However, overhead structures may be permitted, providing their height
does not exceed the limitations established by the applicable aviation authorities (e.g., Federal
Aviation Authority [FAA]), local authority having jurisdiction (AHJ).
The interference of overhead conductors on microwave is seldom caused by the height of the
wooden structures, but rather by the presence of conductors. A structure height that does not
exceed the height of the antennas and is not closer than 0.20 m (1/8 mile [mi]) to the side or
rear of the antenna will not require investigation. When crossing in front of an antenna, the
pole line height should not exceed 1/100 of the distance to the antenna.
Selection of Base Pole
A base should have the height that will satisfy the general requirements of the pole line, based
on the average ground contour and ultimate number and kind of attachments. A crossing pole
should not be selected as the base pole. The height of the base pole is used for calculating the
required strength of the line.
Diameter and Depth of Holes
Diameter of Pole Holes
The center of the pole hole is located at the point of the work location on the construction
work prints. Many times this point is indicated in the field by a stake or a painted mark. The
designer should ensure that the diameter of each pole hole is the same from the top to the
bottom. Ensure that it is large enough to leave 101 millimeters (mm [4 inches (in)]) of free
space around the pole. This space is used for the backfill and tamping.
Depth of Pole Holes
When practical, pole holes should be dug deep enough to provide for planned changes in
grade.
Average Depth in Firm Ground or Solid Rock at Ground Level
If the diameter of a pole hole in solid rock is 0.6 m (2 ft) or more, the pole hole should be the
same depth as a hole in average firm ground (see Table 5.40).
© 2007 BICSI®
5-167
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 4: Aerial Construction Practices
Diameter and Depth of Holes, continued
Solid Rock below Ground Level
When solid rock is found below the ground level, set poles to the minimum depths shown in
Table 5.36. When solid rock is found within 152 mm (6 in) of the required depth of setting in
firm ground, the pole may be set at this reduced depth. This will avoid blasting, provided that
the adjacent poles are set to the full standard depth.
Methods of Digging Pole Holes
Pole holes can be dug with hand tools, an earth boring machine, a water jet, or dynamite.
Digging Holes with Hand Tools
Holes may be dug with the following hand tools (see Figure 5.70):
•
Long-handled, straight shovels and digging spoons
•
Goosenecked shovels
•
Digging bars
The area around the hole should be clear of earth removed from the hole.
OSP Design Reference Manual, 4th edition
5-168
© 2007 BICSI®
Section 4: Aerial Construction Practices
Chapter 5: Pathways and Spaces
Methods of Digging Pole Holes, continued
Figure 5.70
Digging pole hole with hand tools
Digging
Spoon
1.52 m (5 ft)
Shovel
As deep as can
easily be dug with
1.52 m (5 ft) shovel
2.4 m (8 ft) straight
handle shovel
Bend-in cut edges
Aproximately 51 mm (2 in)
51 mm
(2 in) Hole
Required
depth
Outline of
proposed holes
Barrel with
ends Removed
ft
in
m
m
© 2007 BICSI®
=
=
=
=
About 0.3 m
(1 ft)
Foot
Inch
Meter
Millimeter
5-169
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 4: Aerial Construction Practices
Methods of Digging Pole Holes, continued
Using the long-handled, straight shovel or a digging bar, depending upon soil conditions, the dirt
in the bottom of the hole should be loosened. A digging spoon is then used to remove the loose
earth. The digging spoon is then pried against the side of the hole to gain leverage. The bottom
of the hole is squared off to the full diameter.
Large rocks that cannot be removed by hand or with the digging spoon should be shifted from
side to side and dropped to the bottom of the hole. The next step is to backfill around the rocks
and thoroughly tamp the soil. The hole should be dug deep enough to cover the rocks.
The sides of the hole should be shored if it is likely to cave in. A barrel with the head removed
or a section of metal culvert pipe may be used for this purpose. As the soil is removed, the
shoring should be forced down. The shoring can be removed easily and reused if the barrel
or culvert pipe is cut lengthwise and the cut edges are bent over. Two holes are drilled near
the top of the barrel or culvert pipe to attach a winch line. This line is used for pulling the
barrel or culvert pipe from the hole.
OSP Design Reference Manual, 4th edition
5-170
© 2007 BICSI®
Section 4: Aerial Construction Practices
Chapter 5: Pathways and Spaces
Methods of Digging Pole Holes, continued
Boring Holes with Earth Boring Machine
Earth boring machines are used to excavate holes up to 508 mm (20 in) in diameter and as
deep as 2.1 m (7 ft). The following general procedure is used with many manufacturers of
this type of equipment:
1. Position the machine to place the auger of the earth borer directly over the hole location.
2. Set the brake on the machine to stabilize it at the placing location. If the machine is
equipped with wheels, chuck the wheels to prevent accidental movement. If the machine
is track driven, lock the track to prevent movement during the placement operation.
3. Engage the auger at a low speed of about 25 revolutions per minute (rpm). Control the
engine speed to ensure a uniform removal of the soil. Bore the hole to a depth of about
457 mm (18 in).
4. Raise the auger above the ground. Increase the rotation speed of the auger to throw
off the excavated soil. The type of soil encountered can be determined by the first soil
removed.
5. Repeat the process for another 457 mm (18 in) including raising the auger and throwing
off the excavated soil until the desired depth is attained. Should large stones lodge in the
auger blade, loosen and remove them.
When boring in sandstone, shale or frozen ground, maintain a slow rotation speed. A speed
of about 125 rpm should be used for average soil, sand, or clay.
Water Jet Method of Setting Poles
When caving soil or subsurface water makes other methods impractical, the following method
should be used:
1. Dig the pole hole with hand tools until the soil begins to cave in or water is encountered.
The surface diameter of the pole hole must be 406 mm (16 in) greater than the diameter
of the pole at the butt end.
2. Place the pole vertically into the hole. The pole can be raised using the A frame and winch
cable of a line truck, a hydraulic/mechanical arm, or by hand using pole pikes to hold the
pole vertically erect.
3. Lash a short pike pole to a fire hose and nozzle.
4. Place the nozzle into the hole and turn on the water pressure (see Figure 5.71). The water
will gradually undermine the pole and the pole will sink into place. Move the hose nozzle
around the pole to prevent it from becoming lodged in place.
NOTE:
© 2007 BICSI®
A water pressure of approximately 172 kilopascals (kPa [25 pounds per square
inch (psi)]) is sufficient to move the soil. The quantity of water is more
important than the water pressure. As the pole sinks into the hole, ease off the
winch line, lower the hydraulic/mechanical arm, or ease off the pike poles.
5-171
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 4: Aerial Construction Practices
Methods of Digging Pole Holes, continued
Figure 5.71
Digging pole hole with a water jet
Hose
Short pike pole lashed to hose
Nozzle
5. After the pole has sunk to the required depth, turn off the water and remove the hose and
pike pole. Face and straighten the pole using a cant hook and fill the hole around the pole
with the overflow of sediment. Tamping is usually not required in this type of placement.
A swamp fixture may be required to hold the pole in place in a permanently erect position.
Blasting Pole Holes
OSP designers must consult with the appropriate governmental agency prior to blasting.
OSP Design Reference Manual, 4th edition
5-172
© 2007 BICSI®
Section 4: Aerial Construction Practices
Chapter 5: Pathways and Spaces
Methods of Raising and Setting Poles
NOTE:
The term pole support throughout this document is interchangeable with the term
deadman.
Line Truck Method
Setting poles by a line truck is the simplest and safest method in most cases. Some line trucks
are equipped with an A frame derrick and a winch line. These can be used to raise and then
lower the pole into the hole using the winch line. If the line truck is equipped with a hydraulic/
mechanical derrick, the derrick is usually equipped with a mechanical auger. This type of rig
can be used to raise and then lower the pole into position in the hole. This rig can be used to
set poles that do not exceed 13.7 m (45 ft).
A-Frame Line Truck
An A-frame line truck is equipped with an A-shaped frame on the rear of the truck, allowing
the use of the winch line and frame to raise poles and set them in their holes. The frame is
raised to a position high enough to raise the pole to the desired level. The winch line is
positioned through the apex of the A frame through the winch line pulley and then affixed
around the pole at a location two-thirds from the butt end of the pole. The winch line is
tightened and the pole is lifted off the ground with the butt end of the pole still on the ground
(see Figure 5.72).
The line crew can then position the butt of the pole at the edge of the pole hole and raise the
A frame higher, while holding the pole in position. Once the pole attains a vertical position,
loosening the winch line can lower it until the pole rests on the bottom of the hole. Cant hooks
can be used to position the pole as desired and then the hole can be backfilled and tamped.
Pike poles should be used to brace and hole the pole vertically. The pole should then be
straightened and centered in the hole. The foreman or lead technician should take sightings
on the pole from two directions at least 6 m (20 ft) from the pole. The first sighting would be
taken from a location perpendicular to the direction of the lead of the pole line. A second
sighting should be taken in line with the lead of the pole line. A plumb bob attached to a length
of cordage can be used to ensure vertical alignment from both directions (see Figure 5.73).
© 2007 BICSI®
5-173
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 4: Aerial Construction Practices
Line Truck Method, continued
Figure 5.72
Setting pole using A-frame line truck
Derrick head over
center of hole
0.3 m
(1 ft)
minimum
Above
balance
point
Winch line
pulling
against top
and back
of hook
Rear support
jacks
ft = Foot
m = Meter
OSP Design Reference Manual, 4th edition
5-174
© 2007 BICSI®
Section 4: Aerial Construction Practices
Chapter 5: Pathways and Spaces
Line Truck Method, continued
Figure 5.73
Sighting pole to ensure it is level and plumb
Plumb bob in line
with center of hole
First sighting
position
Second sighting
position
© 2007 BICSI®
5-175
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 4: Aerial Construction Practices
Line Truck Method, continued
When backfilling in normal soil, the entire hole should be backfilled and tamped by partially
backfilling the hole for approximately 152 mm (6 in). Using a hand tamp or a mechanical
tamp, the backfill should be tamped until compacted. The process should be repeated until the
hole is completely filled. Any excess fill that remains in a mound surrounding the pole does not
need to be removed. Time and weather will use the fill to completely fill the ground.
When the pole is fully placed, the winch line is released and removed from the pole.
Line Truck Equipped with Hydraulic/Mechanical Derrick
Line trucks equipped with a hydraulic/mechanical derrick provide a less labor intensive
method of pole setting. The derrick is a power derrick and usually has mechanical claws on its
end that can be used to grasp the pole and steady it. In addition, the winch line runs through
the derrick and can be used to help raise the pole and position the pole for setting.
The winch line is attached to the pole at a location that is 1/3 the length of the pole from the
bottom. The derrick is lowered and the pole is grasped with the mechanical claw. The winch
line is tightened until it is barely loose on the pole. The derrick is raised, allowing the butt of
the pole to remain on the ground. Once raised upright to a vertical position, the line crew can
assist in the positioning of the pole into the pole hole. Once aligned with the hole, the derrick
can be used to lower the pole along with slacking off on the winch line.
Cant hooks can be used to position the pole as desired and then the hole can be backfilled and
tamped.
The pole is straightened and centered in the hole. The foreman or lead technician should take
sightings (Figure 5.71) on the pole from two directions at least 6 m (20 ft) from the pole. The
first sighting would be taken from a location perpendicular to the direction of the lead of the
pole line. A second sighting should be taken in line with the lead of the pole line. A plumb bob
attached to a length of cordage can be used to ensure vertical alignment from both directions.
When backfilling in normal soil, the entire hole should be backfilled and tamped by partially
backfilling the hole for approximately 152 mm (6 in). Using the line truck’s mechanical tamp,
the backfill is tamped until compacted. The process is repeated until the hole is completely
filled. Any excess fill that remains in a mound surrounding the pole does not need to be
removed. Time and weather will use the fill to completely fill the ground.
When the pole is fully placed, the winch line and mechanical claw are released and the winch
line is removed from the pole.
OSP Design Reference Manual, 4th edition
5-176
© 2007 BICSI®
Section 4: Aerial Construction Practices
Chapter 5: Pathways and Spaces
Line Truck Method, continued
Hand and Pike Pole Method
The hand and pike pole method is used to set light poles only.
A butting board is placed 51 mm (2 in) by 254 mm (10 in) by 2.7 m (9 ft) in the hole. Two
digging bars can be used in place of the butting board when placing in firm soil.
The pole is positioned with the butt over the pole hole, the butt being solidly against the butting
board or digging bars. A member of the line crew is stationed on each side of the pole.
Two cant hooks are placed in opposite directions on the pole 305 mm (12 in) above the ground
line. This process will prevent the pole from rolling off the pike poles.
The top end of the pole is raised by hand. The butt end of the pole is driven into the hole
against the butting board or digging bars. A deadman is placed under the pole to help hole
the pole, which the line crew reposition to continue raising the pole (see Figure 5.74).
The pikes are then set into the pole at the upper end. The pole is raised by pushing upward
on the pike poles. The pole must not turn during this process. The pole should be raised until
it is vertical and in the hole.
The digging bar or butting board is then removed from the hole. Using the cant hooks, the
pole should be straightened and aligned to final position.
The foreman or lead technician should take sightings on the pole from two directions
(Figure 5.72) at least 6 m (20 ft) from the pole. The first sighting would be taken from a
location perpendicular to the direction of the lead of the pole line. A second sighting should
be taken in line with the lead of the pole line. A plumb bob attached to a length of cordage
can be used to ensure vertical alignment from both directions.
When backfilling in normal soil, the entire hole should be backfilled and tamped by partially
backfilling the hole for approximately 152 mm (6 in). Using a hand tamp or a mechanical
tamp, the backfill should be tamped until compacted. Repeat the process until the hole is
completely filled. Any excess fill that remains in a mound surrounding the pole does not need
to be removed. Time and weather will use the fill to completely fill the ground.
© 2007 BICSI®
5-177
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 4: Aerial Construction Practices
Line Truck Method, continued
Figure 5.74
Raising pole using manpower, pole pikes, and a deadman pole support
Pike pole
Gant hooks
Pole support
Butting board
OSP Design Reference Manual, 4th edition
5-178
© 2007 BICSI®
Section 4: Aerial Construction Practices
Chapter 5: Pathways and Spaces
Line Truck Method, continued
Backfilling and Tamping
The space in a pole hole must be filled with earth (backfill) after a pole is in position by a
process called backfilling. The backfill is tamped for the full depth of the pole hole. Every
152 mm (6 in) of the backfill must be tamped thoroughly prior to adding more backfill. If
available, large stones should be used as wedges as needed. Rocks should be wedged firmly
around the pole when it is set in solid rock.
Ensure that unstable backfill, such as snow or ice, is not mixed with the soil being used. The
excess fill should be banked and paced at least 152 mm (6 in) high, damming it around the
base of the pole. If it is available, gravel should be used for the top section of the backfill.
Raking Poles
A raked pole (see Figure 5.75) is one that inclines from a true vertical position. Poles are
raked to ensure that the pole top will be in line after strain is applied by attachment. Guyed
poles are normally raked by pulling them off their vertical position with the guy or by offsetting
the pole hole.
Dead End and Corner Pole Raking
A raked pole is one that tilts or inclines from a perfect vertical position. Poles are raked to
ensure that the pole top will be in line with the pole line after the pole settles into its final
position and/or after a strain is applied to the pole by an attachment. Guyed poles are raked
by pulling the top of the pole off the vertical position with a guy. Poles can also be raked at
the butt end by offsetting the orientation of the pole hole prior to setting the pole.
The amount of rake is equal to the diameter of the pole at the top. The butts of a corner pole
with a pull of 15.2 m (50 ft) or more must be set 305 mm (12 in) off from the line to provide
the necessary rake alignment.
Push brace poles are raked with the position of the butt of the pole in-line with the pole line.
The amount of rake must be 152 mm (6 in) for each 6 m (20 ft) of pole height above the
ground in firm soil. When rock is found, half rake should be used.
© 2007 BICSI®
5-179
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 4: Aerial Construction Practices
Raking Poles, continued
Figure 5.75
Raking pole prior to tamping
Top of pole pulled
out of line
Pole butt set
in from line
Approximately
0.3 m (1 ft)
ft
m
=
=
Foot
Meter
OSP Design Reference Manual, 4th edition
5-180
© 2007 BICSI®
Section 4: Aerial Construction Practices
Chapter 5: Pathways and Spaces
Footings for Poles
Poles set in soft or unstable soils require additional support. This is provided by footings (see
Figure 5.76). Footings will increase the bearing area of the pole butt. A platform built on the
surface of the ground can also provide the necessary support.
Plank Footings
Plank footings are used to support poles where the soil is unstable and the poles tend to sink
into the soil. Tamp the earth at the bottom of the pole hole. This tamping will provide a solid
foundation for a plank footing.
To accomplish this, place a treated plank of at least 51 mm (2 in) by 305 mm (12 in ) by
610 mm (24 in) in the bottom of the pole hole. If additional footing surface is required because
of soil conditions, two planks should be installed crosswise.
The pole should be raised and the butt should be centered on the plank footing. Cant and
camber of the pole should be aligned, the hole should be backfilled, and the backfill tamped
around the pole.
Figure 5.76
Plank footing for pole
Pole butt
Plank footing
© 2007 BICSI®
5-181
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 4: Aerial Construction Practices
Footings for Poles, continued
Catenary Span Poles
Catenary span poles (see Figure 5.77) are used to support special spans that are substantially
longer than normal span lengths. These spans impose a heavy midspan load on the crossing
poles and on a pole with a head guy. The load can become heavy enough to slowly drive the
poles into the ground unless they are properly supported.
Catenary span poles set in solid rock, shale, coral and hardpan do not require footings because
the ground supports them from below. Catenary span poles set in clay require treated planking
arranged in a square to properly support them. Catenary span poles set in sand, gravel, and
loam require a combination of plank and log footing (see Figure 5.78). Catenary span poles
should not be set in swamps or marshes. When set in these conditions double the earthbearing planks.
Figure 5.77
Plank footing and catenary design
51 mm (2 in)
101 mm (4 in)
610 mm
(24 in)
610 mm
(24 in)
Four creosoted anchor planks
or equivalent not less than
51 mm x 305 mm x 610 mm
(2 in x 12 in x 24 in). Use
galvanized wire nails, not smaller
than 16D.
in
mm
=
=
Inch
Millimeter
OSP Design Reference Manual, 4th edition
5-182
© 2007 BICSI®
Section 4: Aerial Construction Practices
Chapter 5: Pathways and Spaces
Footings for Poles, continued
Figure 5.78
Plank and log footing and catenary design
Two half lengths of
3 m 76 cm (10 ft 30 in)
circumference reinforcing
strut or equivalent
19 mm x 59 mm
(0.75 in x 2.25 in)
Square washer (length)
in crossarm bolt or
stubbing bolt
ft
in
m
mm
=
=
=
=
610 mm
(24 in)
Creosoted anchor planks
or equivalent not less than
51 mm x 305 mm x 610 mm
(2 in x 12 in x 24 in)
nail planks with 30D
galvanized wire nails
2 m
(5 ft)
Foot
Inch
Meter
Millimeter
Plank Bracing and Platform Supports
Platform supports are used to provide stability for a pole when extra ground footing surface is
needed. This extra support will prevent the pole from sinking into the soft ground from the
load. Treated wood should be used for these supports. If treated timbers are not available,
cypress or cedar timbers can be substituted.
The following steps outline the installation:
1. The pole must be set 305 mm (12 in) deeper than normal.
2. Drill three 17.5 mm (11/16 in) holes in the platform joists. Center two of the holes 101 mm
(4 in) from each end. Another hole is centered in the midpoint of the joist. Drill 1473 mm
(58 in) holes in both ends of both the upper and lower plank braces. Center these holes
76 mm (3 in) back from the brace ends.
3. Drill three holes through the length of each spacing block. Align these holes with the end
holes of the platform joist.
© 2007 BICSI®
5-183
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 4: Aerial Construction Practices
Footings for Poles, continued
4. Use corrosion resistant, treated nails (e.g., 10 penny galvanized) to secure the cross
planks to one of the platform joist. Nail five cross planks on each end of the platform joist.
Space the cross planks as shown in Figure 5.79, leaving space for the pole in the center.
5. Place the platform around the pole, with the platform joist bearing against the face of the
pole. Place the second platform joist against the opposite side of the pole and nail the
cross planks to the second joist. It may be necessary to install spacing blocks and bolts
temporarily to provide rigidity and alignment. Insert a wood bit in the center hole of the
platform joist and drill a hole through the pole.
6. Bolt the platform joist and braces in place on the pole. Use galvanized bolts with square
galvanized washers under the bolt heads and square galvanized washers and lock washers
under the nuts. Hand tighten the nuts prior to tightening them with a wrench.
Figure 5.79
Platform support
76 mm (3 in)
Maching bolts with
square washers
Upper plank brace
Lower plank
brace
Spacing block
Cross plank
Platform joist
Depth of setting
in
mm
= Inch
= Millimeter
OSP Design Reference Manual, 4th edition
5-184
© 2007 BICSI®
Section 4: Aerial Construction Practices
Chapter 5: Pathways and Spaces
Footings for Poles, continued
Platform Supports with Side Guys
On occasion, poles may require both platform support and side guys (see Figure 5.80). Side
guys are used in lieu of diagonal plank braces.
Figure 5.80
Side guys and platform support
© 2007 BICSI®
5-185
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 4: Aerial Construction Practices
Footings for Poles, continued
Platform Supports at H Fixtures
Refer to Figure 5.81 for this type of installation. The cross-plank spacing and the construction
procedures described previously are modified as needed. Diagonal plank braces will not be
required.
Figure 5.81
Platform support at H fixture
H fixture
Plaftorm
support
OSP Design Reference Manual, 4th edition
5-186
© 2007 BICSI®
Section 4: Aerial Construction Practices
Chapter 5: Pathways and Spaces
Ground Braces
Ground braces are used where the soil is unstable and will not keep the pole from leaning
sideways. They are also used where there is not sufficient space to allow the installation of
side guys or pole braces. Where the load on the pole is not large enough to warrant the use
of a guy, ground braces will be required.
Log Braces
Ground braces can be made of logs 203 mm (8 in) to 279 mm (11 in) in diameter, rather than
timbers (see Figure 5.82). Treated logs must be used whenever available. The log on the top
should be 1.2 m (4 ft) to 1.8 m (6 ft) below the ground line. The log on the bottom should be
0.6 to 1.2 m (2 to 4 ft) long, depending on the size of the pole. Logs should be notched to fit
the pole. The pole should not be notched. The following steps should be taken:
1. If a bottom brace must be installed, stop the backfilling of the pole hole about 305 mm
(12 in) from the bottom. Widen the hole to permit installation of the bottom log.
2. Place the bottom log firmly against the pole. To ensure compaction, tamp the backfill
completely around and over it. Continue backfilling the hole to a depth of 0.6 m (2 ft)
of the ground line. Dig the top of the pole hole wide enough to allow for installation of
the top log.
3. Place the top log firmly against the pole with the long axis of the log parallel to the line of
the lead. Tamp the backfill completely around and over it ensuring compaction. Complete
the backfilling and tamping of the pole hole.
© 2007 BICSI®
5-187
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 4: Aerial Construction Practices
Ground Braces, continued
Figure 5.82
Log ground brace
Direction of pull
Logs notched
to fit against
pole
OSP Design Reference Manual, 4th edition
5-188
© 2007 BICSI®
Section 4: Aerial Construction Practices
Chapter 5: Pathways and Spaces
Ground Braces, continued
Plank Ground Braces
Plank ground braces are used to support poles and prevent leaning in unstable soil. When a
pole is supporting an unguyed corner load, do not use plank ground braces. Log braces should
be used instead. Plank ground braces should be installed as follows:
1. Obtain two treated planks 51 mm (2 in) thick, 305 mm (12 in) wide, and 610 mm (24 in)
long. Stop the backfilling of the pole hole about 0.6 m (2 ft) below ground line. Dig the top
of the pole hole wide enough to permit installation of the planks.
2. Drill two holes in each plank, locating the holes midway in the width of the planks at an
equal distance from each end. The distance between the holes should not be smaller than
the diameter of the pole.
3. Using two galvanized bolts, bolt the planks to the pole parallel to the lead of the pole line
near the ground line. Use two galvanized through bolts with square galvanized washers
under the bolt heads and square galvanized washers and lock washers under the nuts.
While the bolts are loose, slide the brace down the pole until the top of the brace is
152 mm (6 in) below the ground line. Tighten the nuts; backfill and tamp the hole ensuring
compaction.
Push Braces
Push braces are used instead of anchor guys only when there is not sufficient space to install
the guys. Use standard sized poles for push braces and frame the braces to bear flush against
the poles. In framing, treated poles do not expose the untreated wood. Dimensions for the
various push braces are given in Table 5.38.
Length of Push Braces
Push braces must be the same class as the pole it supports. Table 5.41 lists the length of push
braces under the following conditions:
1. The pole and push brace are at the same ground level.
2. The distance along the ground from pole to brace is equal to one-half the distance from
the ground to the brace attachment on the pole.
3. The brace is attached 0.9 m (3 ft) from the top of the pole or directly below the second
gain.
The pole and its brace are set to standard depth for poles in average firm ground.
© 2007 BICSI®
5-189
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 4: Aerial Construction Practices
Push Braces, continued
Determining Individual Push Brace Length
When conditions do not allow the data in Table 5.41 to be used, the push brace length can
be determined as follows:
1. Draw a vertical line to represent the pole. A scale of 6 mm = 305 mm (1/4 in = 12 in)
is generally convenient. Draw a second line half as long as and perpendicular to the
midpoint between the ground line and the point of brace attachment on the vertical line
(see Figure 5.83).
2. Indicate on the diagram the point at which the brace will be attached to the pole. Draw
a third line from this point through the outer end of the perpendicular (1 above) to the
ground line to represent the brace. Sketch in the approximate ground profile between
the pole and the brace.
3. Scale the length of the brace between the point of attachment to the pole and ground
level. Add to this figure the depth of setting for the brace. This sum represents the
approximate length of push brace required. Greater accuracy can be obtained by using
a scale of 12.7 mm = 305 mm (1/2 in = 12 in).
Table 5.41
Lengths of pole braces
Length of Pole
Distance from Pole to
Brace at Ground line
(Center to Center)
Length of
BraceRecommended
m
(ft)
m
(ft)
m
(ft)
6
(20)
2.1
(7)
5.5
(18)
6.7
(22)
2.4
(8)
6
(20)
7.6
(25)
2.75
(9)
7
(23)
9.1
(30)
3.43
(11.25)
8.5
(28)
10.7
(35)
4.1
(13.5)
10
(33)
12
(40)
4.9
(16)
11.6
(38)
13.7
(45)
5.6
(18.25)
13.1
(43)
15
(50)
6.25
(20.5)
14.6
(48)
ft
m
=
=
Foot
Meter
OSP Design Reference Manual, 4th edition
5-190
© 2007 BICSI®
Section 4: Aerial Construction Practices
Chapter 5: Pathways and Spaces
Push Braces, continued
Figure 5.83
Measuring for push brace
Brace attachment
0.9 m (3 ft) from
top of pole
1.
Draw vertical line of proper length
to represent pole.
2.
Locate point of brace attachment.
3.
Draw line representing brace at
proper angle.
4.
Indicate ground line profile between
pole and brace.
5.
Scale length of brace between pole
and ground profile.
6.
Add depth of setting to value
obtained in 5, above.
7.
Select length of brace that will
meet conditions.
Height = 2
Lead = 1
Pole shown is
12 m (40 ft) long.
Butt of brace
Ground line
of pole
Ground
profile
1.83 m (6 ft)
ft
m
= Foot
= Meter
© 2007 BICSI®
5-191
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 4: Aerial Construction Practices
Push Braces, continued
Position of Push Braces
On poles carrying cable only, pole braces are attached approximately 0.9 m (1 ft) from the
pole top.
The point at which push braces are attached to open-wire poles depends upon the wire load.
If the pole carries only one crossarm, the push brace is attached under the crossarm. If the
pole carries multiple crossarms, the brace is attached at the center of the wire load.
Installation of Push Braces
Push Brace at Single Poles
A push brace (see Figures 5.84 and 5.85) may be used instead of a side guy when field
conditions do not permit the installation of an anchor and guy. The lead-over-height ratio
should be greater than 1/4 to 1, but less than 1 to 1. A lead-over-height ratio of 1/2 to 1 is
standard. Push braces are installed by:
1. Digging a hole for the push brace at the desired location. This hole should be deep enough
to reach solid footing.
2. Placing two treated plank footings (crossed) or the approved equivalents in the brace hole.
3. Raising and positioning the pole brace; it should be steadied with pike poles. Backfill the
brace hole and tamp the soil. Drill a hole through the pole in line with the attaching bolt
hole in the pole brace.
4. Attaching the push brace to the pole. Secure the brace to the pole with a galvanized
through bolt.
5. Placing the through bolt in the reinforcing bolt hole and tightening the nut. This bolt will
prevent the brace from splitting.
A push brace bracket can be used to increase the stability of the attachment to the push brace
and in line pole. The bracket comes in two main pieces which mount to the top of the push
brace and the point of attachment of the inline pole. The bracket can be bolted onto the two
locations and secured. The push brace can then be installed into the brace hole and leaned
against the inline pole, aligning the two sections of the bracket. Once the two sections of the
bracket mate, the through locking bolt should be installed and secured.
OSP Design Reference Manual, 4th edition
5-192
© 2007 BICSI®
Section 4: Aerial Construction Practices
Chapter 5: Pathways and Spaces
Installation of Push Braces, continued
Figure 5.84
Push brace on single pole
Crossarm bolt to prevent
splitting of brace
19 mm x 57 mm
(0.75 in x 2.25 in)
square washers
Crossarm bolt or stubbing
bolt shall pass through
brace at this point
Hole shall be dug
to reach solid footing.
Depth shall be at least
0.6 m (2 ft) except
in rock.
A ground brace may be used
if necessary to prevent pole
from lifting out
ft
in
m
mm
=
=
=
=
© 2007 BICSI®
Foot
Inch
Meter
Millimeter
Two creosoted anchor planks or approved
equivalent not less than 51 mm x 305 mm x 508 mm
(2 in x 12 in x 20 in). Size of planks may vary
with the condition of the soil but shall not be
less than dimensions given.
5-193
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 4: Aerial Construction Practices
Installation of Push Braces, continued
Figure 5.85
Push brace on H fixture
Cross arm brace
Direction of pull
Attaching bolt
Reinforcing bolt
OSP Design Reference Manual, 4th edition
5-194
© 2007 BICSI®
Section 4: Aerial Construction Practices
Chapter 5: Pathways and Spaces
Installation of Push Braces, continued
Double Push Braces
Double push braces (one on each side) can be used to reinforce a pole line when other types
of braces or anchors (e.g., two-way storm guys) cannot be installed. Figure 5.86 illustrates
this type of installation.
Each brace of a double push brace should be installed as described in Push Braces at Single
Poles. If the first method (i.e., direct attachment of push brace without brace bracket) is
employed, a through bolt of sufficient length should be used to pass through both push braces
and the inline pole.
Figure 5.86
Double push brace
© 2007 BICSI®
5-195
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 4: Aerial Construction Practices
Installation of Push Braces, continued
Push-Pull Braces
Push-pull braces are used only at locations where field conditions do not permit the use of
anchors and guys. They are installed as follows:
1. Dig a hole for the brace. Make the vertical distance from the ground to the bottom of the
brace hole as shown in Figure 5.87. Provide a trench at the bottom of the brace hole for a
log anchor. (See Table 5.41 for length requirements.)
2. Frame the log anchor and the bottom of the brace to provide a secure fit between the
anchor and the brace.
3. Attach the log anchor to the brace with a galvanized through bolt, fitted with two square
washers, a lock washer, and a nut.
4. Raise and set the push-pull brace in the brace hole.
5. Hold the brace in position against the pole with pike poles. Backfill the brace hole to
ensure compaction. Attach the brace to the pole as described in Push Braces at Single
Poles.
6. Reinforce the brace-to-pole attachment (when push brace brackets are not used) with six
wraps of galvanized wire around the pole and the brace at a point below the attaching
bolt. Drive a lag bolt of the required length equipped with curved washers, lock washer,
and a nut between the wires where the wires pass between the brace and the pole.
Tighten the wire wraps by tightening the nut on this bolt.
OSP Design Reference Manual, 4th edition
5-196
© 2007 BICSI®
Section 4: Aerial Construction Practices
Chapter 5: Pathways and Spaces
Installation of Push Braces, continued
Figure 5.87
Push-pull brace
Crossarm bolt to prevent
splitting of brace.
19 mm x 57 mm
(0.75 in x 2.25 in)
square washer under
head and nut of bolt.
12.7 mm x 114 mm
(0.5 in x 4.5 in)
galvanized drive
screw
Use galvanized wire wrapping
where line carries more than
20 wires. Make six turns. Tighten
wire wraps by means of crossarm
bolt and curved washers
83 mm x 83 mm x 80 mm
(3.25 in x 3.25 x 3.125 in),
19 mm (0.75 in) hole.
Ground brace may be
used if necessary to
prevent pole from
lifting out
1.2 m - 1.83 m
(4 ft - 6 ft)
according to
the nature of
the soil
1.83 m
(6 ft)
ft
in
m
mm
=
=
=
=
© 2007 BICSI®
Crossarm bolt or
stubbing bolt shall
pass through brace
at this point
19 mm x 57 mm
(0.75 in x 2.25 in)
square washer under
head and nut of bolt
Brace and log notched to
frame together if timber is
treated. Do no expose
untreated wood.
Length of crossarm bolt
or stubbing bolt not less
than 203 mm (8 in) from
end of brace
152 mm - 203 mm
(6 in - 8 in)
diameter
Foot
Inch
Meter
Millimeter
5-197
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
OSP Design Reference Manual, 4th edition
Section 4: Aerial Construction Practices
5-198
© 2007 BICSI®
Section 5: Spaces
Chapter 5: Pathways and Spaces
Spaces
Introduction
In outside plant (OSP) construction, various types of spaces perform a variety of functions.
This section covers space types, including:
•
Maintenance holes (MHs).
•
Handholes (HH), pedestals, and cabinets.
•
Controlled environmental vaults (CEVs).
•
Concrete universal enclosures (CUEs).
Confined Spaces
A confined space is one that a worker can enter and work in but that has limited or restrictive
means of entry or exit and that is not designed for continuous occupancy (e.g., MHs, vaults,
crawl spaces, attics).
In a confined space, harmful gasses or vapors may accumulate or there may not be sufficient
oxygen to support life. Hazardous atmospheres may be classified as:
•
Flammable.
•
Explosive.
•
Asphyxiating.
•
Toxic.
Additional adverse conditions are:
•
Excessive noise (i.e., hearing protection required).
•
Dust accumulation (e.g., combustibles).
•
Flooding/engulfment.
•
Excessive heat (e.g., exhaustion, stroke).
The OSP designer shall comply with all codes, standards, and regulations that address
telecommunications work performed on underground lines in MHs and vaults.
In the telecommunications industry, the following are considered confined spaces:
© 2007 BICSI®
•
Telecommunications MHs
•
Ductbank trenches
•
Tunnels
•
Building entrance facilities (EFs)
•
Vaults (vented and nonvented)
•
Drop ceilings
•
Mechanical equipment rooms (ERs)
•
Motor control cabinets
5-199
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 5: Spaces
Maintenance Holes (MHs)
IMPORTANT:
It is the OSP designer’s responsibility to determine if any spaces to be
entered are defined by an authority having jurisdiction (AHJ) as confined
spaces or permit-required confined spaces and to follow all related codes,
standards, regulations, and procedures dealing with safety.
A MH is considered a confined space.
WARNING:
Be aware of hazards (e.g., explosions, suffocation, entrapment, and vehicular
accidents). Verify that established procedures are in place. Typical
precautions include a minimum two-person crews, barricades, and ventilation.
Carefully follow established procedures.
MHs have multiple uses, including underground cable placement and splicing. They can be
constructed of either:
•
Concrete with metallic access covers.
•
Polyethylene with polyethylene access covers.
MHs are selected based upon size, location and traffic loading. Table 5.42 provides rating
information.
Table 5.42
Maintenance hole ratings
This rating…
Is used for…
Light duty
H-5
H-10
Pedestrian traffic only
Sidewalk applications and occasional nondeliberate traffic
Driveways, parking lots, and off-road application subject to
occasional nondeliberate heavy vehicles
Deliberate heavy vehicular traffic
H-20
NOTE:
The suffix denotes the ability to withstand a gross vehicle weight rating (GVWR) in
tons (e.g., H-5 represents 5000 kilograms (kg [13,396 pounds (lbs)]).
MHs provide accessible space in underground systems for:
•
Placing and splicing cables.
•
Pulling cables.
•
Splicing-in cable stubs.
•
Load coil cases.
•
Maintenance and operation equipment.
•
Repeater cases (e.g., T-1, integrated services digital network [ISDN]).
OSP Design Reference Manual, 4th edition
5-200
© 2007 BICSI®
Section 5: Spaces
Chapter 5: Pathways and Spaces
Maintenance Holes (MHs), continued
MHs must be equipped with:
•
A sump.
•
Corrosion-resistant pulling irons.
•
Cable racks (grounded per applicable electrical code or practice).
MHs should be constructed in such a way that they:
•
Are capable of supporting the heaviest anticipated street traffic weight.
•
Are reasonably waterproof.
•
Provide sufficient racking space for the ultimate number of cables and other equipment
that requires permanent anchorage.
•
Provide adequate entrance for workers and simultaneous and continuous ventilation.
NOTE:
BICSI recommends the placement of a fixed or movable ladder.
Except when needed to support telecommunications equipment, MHs (see Figures 5.88, 5.89,
and 5.90) should not be used as pathways for power and light conductors. For specific details,
consult the applicable safety codes.
If the MH is to be occupied by other utilities, their agreement should be obtained prior to MH
ordering or construction.
Figure 5.88
Typical maintenance hole (cutaway side view)
Cover
Frame
Steps
(as required)
Neck
Brick collar or
precast collar
(neck plastered)
Headroom
Cable racks
Window
recess
Sump
Pulling iron
Ceiling
Ducts
Floor
Single bay
racking area
Ground rod
Pulling iron
Ground rod
Double bay
racking area
© 2007 BICSI®
5-201
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 5: Spaces
Maintenance Holes (MHs), continued
Figure 5.89
Maintenance hole diagram
Installation box to be placed
on 6" of compacted rock or
sand to ensure uniform
distribution of soil pressure
on floor. See manufacturer’s
specifications.
Weight:
Top slab
(w/ 30" dia. opening)
7'
Reinforcement for H-20
traffic bridge loading
OD
13
'O
D
Opening size and
location can vary
Top slab
30"
Diameter
opening
8"
7"
1'
Notch on underside
of top slab to accept
base section
1'
6'
0"
12
'
5" diameter
knock-outs
(4 each end)
Base section
7'
Pull iron
each end
Depth
9'
13" DIA
sump
OD height
8' 1"
6"
6' 0" x 12' 0 Maintenance hole
OD = Outside dimension
OSP Design Reference Manual, 4th edition
5-202
© 2007 BICSI®
Section 5: Spaces
Chapter 5: Pathways and Spaces
Maintenance Holes (MHs), continued
Figure 5.90
Maintenance hole frame, cover, and collar
762 mm
(30 in)
Clear opening
229 m (9 in) or
305 mm (12 in)
as required
Step
adjustment
notch
Grade rings
as required
See detail
12.7 mm (0.5 in) adjusting stud
with double nut and washer
as shown
Collar
Steps grouted
between joints
as required
38 mm (1.5 in) to
51 mm (2 in)
as required
Dry pack
grout
914 mm
(36 in)
152 mm (6 in)
12.7 mm (0.5 in)
diameter insert
Maintenance hole
cover collar
Cross section
Cover Adjustment Detail
Cast iron or
polymer
concrete cover
Cast iron ring
Adjusting studs
with slotted head
for installing into
insert (4 places)
12.7 mm (0.5 in)
diameter inserts
(4 places for
adjustments)
Maintenance hole
cover collar (designed for
H-20 bridge load)
19 mm (0.75 in) diameter
galvanized steel steps grouted
between joints as required
762 mm
(30 in)
Notch to receive
step (available in
305 mm [12 in]
gradering only)
Precast concrete grade rings
(76 mm [3 in], 152 mm [6 in],
305 mm [12 in] heights available)
914 mm
(36 in)
diameter
opening
ft
in
m
mm
=
=
=
=
Foot
Inch
Meter
Millimeter
© 2007 BICSI®
Maintenance hole top
5-203
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 5: Spaces
Maintenance Holes (MHs), continued
MHs have either center conduit entry or splayed conduit entry. The center entry MH (see
Figure 5.91) allows the main duct run to enter at the center of the MH. Cables that are placed
in the duct must be routed to the side wall for racking or splicing. A splayed entry (see
Figure 5.92) does not require the cables to be routed since they align with the cable racks. See
Figure 5.93 for a basic A precast MH.
Figure 5.91
Center conduit tray
Figure 5.92
Splayed conduit entry
OSP Design Reference Manual, 4th edition
5-204
© 2007 BICSI®
Section 5: Spaces
Chapter 5: Pathways and Spaces
Maintenance Holes (MHs), continued
Figure 5.93
Basic A precast maintenance hole
Basic A splayed
Basic A center window
Basic A splayed with
height extension
© 2007 BICSI®
5-205
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 5: Spaces
Choosing Precast or Site-Poured Maintenance Hole (MH)
When determining which MH to order or construct, the following factors should be
considered:
•
Physical space required to construct
•
Number of ducts required
•
Space configuration requirements
•
Duct entry (splayed or center)
•
AHJ requirements for loading
•
Cable racking (single or double)
•
Available placement space for a precast MH
•
Obstacles forcing a nonstandard shape MH
•
Special weight loading requirements
Precast MHs possess certain advantages over poured or cast-in-place MHs. Precast MHs:
•
Are economical compared with those that are poured or cast in place.
•
Are constructed under controlled, uniform conditions that render a quality superior to MHs
poured or cast in place.
•
Are stocked by a precaster and readily available for emergency projects.
•
Can be installed under severe weather conditions.
•
Allow quicker in-service times, and traffic blockage is kept to a minimum.
Cast-in-place (site-poured) MHs generally are preferred when rebuilding or enlarging existing
MHs. They provide flexibility to work around existing cables, existing conduits, lateral
conduits, joint-use utilities, and other structures or barriers. Plans for cast-in-place MHs should
always be reviewed and approved by a civil engineer licensed in the area.
Maintenance Hole (MH) Size Extensions
MHs are designed for use in main and branch conduit systems that require more than three
100 millimeters (mm [4 trade size]) ducts.
At times, conduit depth or other reasons require that a MH be placed below normal depth. It
is then advisable to place the MH’s roof at normal depth below the ground level and increase
the headroom. This eliminates the need for deep collars and provides better lighting and
ventilation in the MH. It is advisable to design the racking space so that sufficient headroom is
left in the MH.
OSP Design Reference Manual, 4th edition
5-206
© 2007 BICSI®
Section 5: Spaces
Chapter 5: Pathways and Spaces
Selecting Maintenance Hole (MH) by Duct Entrance
When main conduit enters the side wall of a MH, the main conduit should be splayed (see
Figure 5.97). Splaying of ducts usually results in a greater racking capacity of a MH and
simplifies future reinforcements. There may be instances when center entrances cannot be
avoided. Center duct entrances reduce the racking capacity and work space available. Refer
to Table 5.43 to select the appropriate MH based on configuration and duct entrance
arrangement. The three configurations are prioritized as recommended first, second, or third
choice.
Table 5.43 is provided for general information. The manufacturer should be contacted for
specific configurations. Angled entrance windows should be considered to facilitate routing of
large cables.
© 2007 BICSI®
5-207
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 5: Spaces
Selecting Maintenance Hole (MH) by Duct Entrance, continued
Table 5.43
Maintenance hole window selection
No. of
Ducts
Ductbank
Configuration
Maintenance Hole Window Selection
Splayed
Use One Side
Splayed
Use Two Sides
Center
4
1st
2nd
3rd
6
1st
2nd
3rd
6
No
2nd
1st
8
1st
2nd
3rd
8
No
1st
2nd
9
No
2nd
1st
10
1st
2nd
3rd
12
1st
2nd
3rd
12
No
1st
2nd
12
No
2nd
1st
14
1st
2nd
3rd
15
No
2nd
1st
16
No
1st
2nd
OSP Design Reference Manual, 4th edition
5-208
© 2007 BICSI®
Section 5: Spaces
Chapter 5: Pathways and Spaces
Selecting Maintenance Hole (MH) by Duct Entrance, continued
Table 5.43
Maintenance hole window selection, continued
No. of
Ducts
Ductbank
Configuration
Maintenance Hole Window Selection
Splayed
Use One Side
Splayed
Use Two Sides
Center
16
1st
2nd
3rd
18
No
2nd
1st
20
No
1st
2nd
24
No
1st
2nd
28
No
1st
2nd
32
No
1st
2nd
© 2007 BICSI®
5-209
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 5: Spaces
Maintenance Hole (MH) Types
Historically, the types of MHs depicted in figures 5.94 through 5.101 represent configurations
of the four most common telecommunications MH types. Manufacturers and some other
organizations may use different terms from the following:
Type A—End wall entrance only
Type J—End and side wall entrance
Type L—End and side wall entrance
Type T—End and both side walls entrance
Figure 5.94
Type A maintenance hole with center conduit window (plan view)
3.7 m (12 ft)
1.83 m
(6 ft)
ft = Foot
m = Meter
Figure 5.95
Type A maintenance hole with splayed window (plan view)
3.7 m (12 ft)
1.83 m
(6 ft)
ft = Foot
m = Meter
OSP Design Reference Manual, 4th edition
5-210
© 2007 BICSI®
Section 5: Spaces
Chapter 5: Pathways and Spaces
Maintenance Hole (MH) Types, continued
Figure 5.96
Type J maintenance hole with center conduit window (plan view)
3.7 m (12 ft)
1.83 m
(6 ft)
ft = Foot
m = Meter
Figure 5.97
Type J maintenance hole with splayed conduit windows (plan view)
3.7 m (12 ft)
1.83 m
(6 ft)
ft = Foot
m = Meter
© 2007 BICSI®
5-211
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 5: Spaces
Maintenance Hole (MH) Types, continued
Figure 5.98
Type L maintenance hole with center conduit window (plan view)
3.7 m (12 ft)
1.83 m
(6 ft)
ft = Foot
m = Meter
Figure 5.99
Type L maintenance hole with splayed conduit window (plan view)
3.7 m (12 ft)
1.83 m
(6 ft)
ft = Foot
m = Meter
OSP Design Reference Manual, 4th edition
5-212
© 2007 BICSI®
Section 5: Spaces
Chapter 5: Pathways and Spaces
Maintenance Hole (MH) Types, continued
Figure 5.100
Type T maintenance hole with center conduit window (plan view)
3.7 m (12 ft)
1.83 m
(6 ft)
ft = Foot
m = Meter
Figure 5.101
Type T maintenance hole with splayed conduit window (plan view)
3.7 m (12 ft)
1.83 m
(6 ft)
ft = Foot
m = Meter
© 2007 BICSI®
5-213
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 5: Spaces
Cable Racking Provisions
When it is necessary to change the elevation of cables, it is desirable to accomplish as much
of the change as possible on the ends of the MH where the cable makes a sweep from the
conduit to the side wall.
Where cables make a considerable change in level, this change should be made in the corners
of the MH behind other cables. These should always be placed against the wall, in the corner,
and formed without sharp bends.
When two conduit structures have different numbers of conduits entering a MH, racking
positions in the MH should be based on the structure having the largest number of conduits.
The cable and completed splice should be supported with cable hangers at each cable rack
(see Figure 5.102).
Figure 5.102
Typical cable maintenance hole
Elevation
change
Cable
hanger
Cable rack
support
Splice
closure
Cable
Conduit
duct bank
OSP Design Reference Manual, 4th edition
5-214
© 2007 BICSI®
Section 5: Spaces
Chapter 5: Pathways and Spaces
Administration
All MHs and MH covers should be clearly labeled with ownership information and type of
utility. The labeling must be unique and the method must be consistent throughout the
installation.
The OSP designer should specify a standard or methodology that addresses the subject of
administration.
Sealing Ducts
All ducts between MHs should be sealed to prevent intrusion of liquids and gases into the
MH. Universal duct plugs are available in a variety of sizes for use in unoccupied ducts. In the
ducts where the cable has been installed, ducts can be sealed by putty sealant, cementitious
compounds, and hydraulic cement.
Lateral or subsidiary conduits to buildings must be sealed. Innerducts entering a building must
be firestopped.
Openings, Covers, and Frames
Construct MH roof openings and necks (i.e, collars) so that they are large enough to
accommodate the smallest inside measurement of a standard MH cover frame.
Collars may be constructed of brick; however, precast collars are more easily placed.
If the vertical distance between the MH ceiling and the street level exceeds 610 mm
(24 inches [in]), use the 762 mm (30 in) collar to place permanent steps in the neck of the
MH.
If a MH has two or more openings, all of the openings should be the same size. At least one
opening should be provided for MHs up to 3.7 meters (m [12 feet (ft)]) long, two openings
over 3.7 m (12 ft) long, and three openings over 6 m (20 ft) long. The number of MH openings
is doubled for center-racked MH.
Select MH covers based on the environment where they are placed. For instance, a MH
located beneath a traffic lane must have a cover capable of supporting the traffic’s weight
(e.g., type B, SB). For light loads such as grass areas, use type R.
For frames and covers, the 762 mm (30 in) size is recommended for all applications and
should be specified for use with precast MHs. Although other frames and covers are
available, their use is not generally recommended. It is easier to get into and out of the
762 mm (30 in) size, especially with a blower or pump hose in the opening, and there is more
room for placing apparatus into the MH. Examples of available frames and covers are listed in
Table 5.44.
NOTE:
© 2007 BICSI®
See Figures 5.89 and 5.90 for examples of MH frames and covers. Sizes of MH
frames and covers vary from one region to another. The OSP designer must be
aware of customary sizes of MH frames and covers in the region where the work
is to be performed.
5-215
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 5: Spaces
Openings, Covers, and Frames, continued
Table 5.44
Maintenance hole frames and covers
Type
Opening
Diameter
Height of
Frame
Remarks
A
686 mm (27 in)* 279 mm (11 in)
762 mm (30 in)
Has inner cover and sealing gasket;
recommended for central office,
carrier-equipped loading, and critical
junction MHs or wherever a watertight
or secured cover is required
SA
686 mm (27 in)* 143 mm (5-5/8 in)
762 mm (30 in)
Shallow version of A type
B
686 mm (27 in)
762 mm (30 in)
254 mm (10 in)
Most commonly used frame and cover
SB
686 mm (27 in)
762 mm (30 in)
143 mm (5-5/8 in)
Shallow version of A type
D
762 mm (30 in)
51 mm (2 in)
Comes with pentagonal head locking
bolts
G
686 mm (27 in)* 254 mm (10 in)
762 mm (30 in)
Has four equally spaced 25 mm (1 in)
diameter holes in the frame flange to
permit securing the frame to concrete
collars and to 38Y maintenance hole
roofs. Used with both the G (nonlocking) and H (locking) covers
SG
686 mm (27 in)* 143 mm (5-5/8 in)
762 mm (30 in)
Shallow version of G type
Same remarks as G type
H
686 mm (27 in)*
762 mm (30 in)
254 mm (10 in)
Covers only are equipped with two
captive bolts with attached locking plates
that engage the rim of either the B, G
and SG frame
SH
686 mm (27 in)
762 mm (30 in)
143 mm (5-5/8 in)
Shallow version of H type
R
686 mm (27 in)* 38 mm (1-1/2 in)
762 mm (30 in)
Used where not subject to vehicular
traffic.
* 686 mm (27 in) is not recommended.
A and SA Types are not commonly used.
in = Inch
m m = Millimeter
WARNING:
For safety, use only one size frame on MHs with more than one opening.
OSP Design Reference Manual, 4th edition
5-216
© 2007 BICSI®
Section 5: Spaces
Chapter 5: Pathways and Spaces
Maintenance Hole (MH) Extension Rings
Use MH extension rings when pavement resurfacing operations necessitate the raising of MH
covers. These rings are sized to mate with the existing frame and cover. They allow the
opening to be raised to the new pavement level, thus allowing full access without creating a
traffic hazard. Local codes should be checked for the maximum number of rings that can be
used until the collar or MH roof must be raised.
© 2007 BICSI®
5-217
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 5: Spaces
Handholes (HHs)
HHs are smaller than MHs, but the covers provide full access to the entire space inside the
hole (see Figure 5.102). HHs are manufactured as concrete, polyethylene, or composite
structures. They can be placed in the same areas where MHs are placed. When planned for
traffic areas, they must be traffic rated.
When HHs are used in an underground installation, they are used as pull-through points and
shall not be used as splice points.
HHs should:
•
Facilitate cable placement.
•
Have drainage provisions (e.g., drain holes, open bottom, sump hole).
•
Aid cable pulling when the bends exceed either two 90 degree bends or a total of
180 degrees, or the conduit section is so long it must be pulled in two segments.
•
Meet applicable code requirements.
HHs shall not be:
•
Used in a main conduit system or in place of a MH.
•
Larger than 1.2 m (4 ft) long by 1.2 m (4 ft) wide by 1.2 m (4 ft) high.
•
Used in runs of more than three 100 mm (4 trade size) conduits.
•
Shared with electrical installations other than those used for telecommunications.
Conduit entering a HH should be aligned on opposite walls at the same elevation. Some
handholes are available without bottoms for drainage. When installed without bottoms, these
HHs should be equipped with a 101 mm (4 in) layer of small rock in the bottom to prevent
mud from intruding into the HH.
OSP Design Reference Manual, 4th edition
5-218
© 2007 BICSI®
Section 5: Spaces
Chapter 5: Pathways and Spaces
Handholes (HHs), continued
Figure 5.103
Typical handhole
1016 mm
(40 in)
457 mm
(18 in)
Lifting eye
762 mm (30 in)
101 mm (4 in)
terminators
1220 mm
(48 in)
610 mm
(24 in)
in
mm
= Inch
= Millimeter
© 2007 BICSI®
5-219
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 5: Spaces
Location
When planning the location of a HH, the designer should consider:
•
Ground topography.
•
Soil conditions.
•
Location with respect to surrounding structures.
•
Accessibility for personnel.
•
Difficulty in using the HH for placing cable.
OSP Design Reference Manual, 4th edition
5-220
© 2007 BICSI®
Section 5: Spaces
Chapter 5: Pathways and Spaces
Pedestals, Cabinets, and Vaults
Introduction
Pedestals, cabinets, and vaults are housings used for storing splice closures and terminals in
OSP. Smaller housings are generally known as pedestals, and larger ones are known as
equipment or splice cabinets. They provide above-grade environmental protection, security,
and quick access to splice closures, terminals, excess cable, and optical fiber equipment.
Vaults provide environmental protection, security, and access to splice cases, cables, and
distribution equipment. They may be above or below the ground.
Pedestals, cabinets, and vaults may be mounted directly in the ground or on concrete pads,
mounting feet/stakes, floor stands, walls, or on poles. Rural Utilities Service (RUS) has
established classifications of pedestals as the general purpose channel type (H) and the dome
type (M). Type H pedestal has either front-only access or back and front access, while
Type M pedestal has top-only access.
These housings may include or provide space for:
© 2007 BICSI®
•
Locking device or hasp.
•
Adjustable mounting bracket/panel to secure taps.
•
Splitters.
•
Couplers.
•
Repeaters.
•
Multiplexers.
•
Transceivers.
•
Line extenders.
•
Amplifiers.
•
Interdiction devices.
•
Mounting hardware.
•
Reels for cross connect wire storage.
•
Warning labels.
•
Grounding/bonding provisions.
•
Identification.
•
Manufacturers markings.
•
Cable knockouts.
•
Grommets.
•
Circuit protectors.
5-221
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 5: Spaces
Introduction, continued
Pedestals, cabinets, and vaults are used in aerial, direct-buried, and underground plant design.
In a direct-buried application, these housings create the capability of flexible cable and
terminal placement. They provide a high concentration of feeder cable to several distribution
cables with even higher cable pair or optical fiber strand needs. This can provide an
economical means of providing service over a short period of time.
When selecting pedestals and cabinets, the designer should consider:
•
Cable bend radius greater or equal to 15 times the cable diameter.
•
Capacity to accommodate four cables for current and future requirements.
•
Capacity to accommodate both inline and butt splice closures.
•
Security (e.g., special bolts, keys, security alarm monitoring).
•
Flood control provisions.
•
Weather-tight seals/gaskets/grommets.
•
Optical cable storage to permit moving the splice closure to a working location.
•
Ventilation for environmental control and/or heat extraction (forced air fan optional).
•
Resistance to rodent and insect intrusion.
•
Environmentally controlled cabinets (fans, heaters, and thermostats included).
•
Color options.
•
Impact (vandalism) resistance.
•
Resistance to dust intrusion.
•
Resistance to water vapor.
•
Chemical resistance.
Ground-Level Pedestals and Cabinet Criteria
Pedestals should be located in areas where water drainage will continue after the installation.
In some instances, the soil grading will be sufficient, while in other instances gravel may have
to be placed in the bottom of the pedestal at specified depths. The location of the pedestal
should be away from traffic conditions that could cause injury to personnel, yet it should be
easily accessible for maintenance.
As an example, a pedestal may be 152 mm (6 in) wide and 101 mm (4 in) deep, and 914 mm
(36 in) above ground. The hole measuring would be classified as a BD4, since it has
approximately 0.01 cubic meters (m3) of volume. The general shape of the housing is usually
rectangular or cylindrical, with the particular shape at the discretion of the manufacturer.
Figure 5.104 shows some standard pedestal and cabinet shapes. The narrow ones are
pedestals, and the larger ones are cabinets. The designer needs to determine the size
requirements and consult manufacturer specifications to select the proper housing.
OSP Design Reference Manual, 4th edition
5-222
© 2007 BICSI®
Section 5: Spaces
Chapter 5: Pathways and Spaces
Cabinets
Cabinets are used for splicing or for placing equipment. A particular use is as a cross-connect
point. Large pair or optical fiber strand count splice cabinets are classified according to their
splice capacity.
Pole/Wall Mounted Cabinets
Pole/wall mounted cabinets must be constructed of corrosion-resistant metal or nonmetallic
materials. The housed components are typically accessed through a door or by removing a
portion of the housing. Special mounting brackets are used to secure cabinets to utility poles or
building walls.
Environmentally Controlled Cabinets
Environmentally controlled cabinets provide a suitable environment for electronic equipment.
The cabinets typically provide air circulation with fans and thermostatically controlled heating
and cooling. The air conditioning units may be internally rack mounted or be physically
attached to the exterior of the cabinet.
Pedestals and cabinets are used to house OSP type twisted pair, optical fiber and community
antenna television (CATV) coaxial cables. Pedestals are typically mounted on a wooden post
or metal stake driven or buried into the earth. Cabinets are placed on poured or fiberglass
foundations.
Both pedestals and cabinets have a mark at the bottom so that the installer knows how much
of the bottom is installed below grade. Both pedestals and cabinets are grounded.
Designers should contact their suppliers for the appropriate pedestal or cabinet size based on
the size, types, and applications of the cables placed in them. Figure 5.104 shows typical
pedestals and cabinets.
© 2007 BICSI®
5-223
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 5: Spaces
Cabinets, continued
Figure 5.104
Pedestals and cabinets
OSP Design Reference Manual, 4th edition
5-224
© 2007 BICSI®
Section 5: Spaces
Chapter 5: Pathways and Spaces
Controlled Environment Vault (CEV)
CEVs are belowground enclosures that house not only the cables and connecting hardware,
but the electronic equipment they are connected to. When planning for CEVs, the designer
should consider shipping the equipment to be housed in them to the CEV manufacturer. The
equipment will be installed in the lower section of the vault and shipped to the job site. At the
job site, the lower section is installed first and the top section placed sealing the container to
the surrounding elements.
CEVs are:
•
Precast concrete structures consisting of top and bottom sections.
•
Available in various sizes. Standard sizes are 1.83 m (6 ft) by 5 m (16 ft) and
1.83 m (6 ft) by 7.3 m (24 ft).
•
Designed to provide underground housing for electronic equipment (e.g., subscriber loop
carrier systems, lightwave digital transmission system generators).
•
Generally placed in close proximity to a MH on a main underground route.
CEVs contain active equipment. Air conditioning is optional depending on where they are
being installed. As a result, they include extensive alarm systems (e.g., door intrusion,
emergency lights, smoke detector, power, moisture). They receive a similar level of security as
the central office (CO) and have controlled entry. It usually requires that the technician or
engineer contact the maintenance center before entering so that the alarm does not trigger a
security dispatch.
The designer must exercise caution when selecting a location for a CEV. Because CEVs are
designed to protect environmentally sensitive equipment, the bottom exhaust air vent must be
above the 100-year flood level.
A private right-of-way (R/W) agreement must be executed prior to the installation of a CEV if
the unit will be placed on a property owned by someone other than the customer. The
customer’s investment made must be protected. The location of the unit depends on execution
of the agreement.
© 2007 BICSI®
5-225
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 5: Spaces
Concrete Universal Enclosure (CUE)
CUEs are aboveground environmentally enclosed cabinets that house OSP cable and
electronic equipment. In some circumstances, a CUE can be used in place of a CEV.
CUEs:
•
Are all-concrete construction, which provides equipment protection and security.
•
Can accommodate six 2.1 m (7 ft) by 584 mm (23 in) equipment racks and provide wall
space for other equipment (e.g., protection blocks).
•
Are designed to provide environmentally controlled housing (e.g., air conditioning/heating
and environmental alarms).
•
Should be used in applications requiring additional security.
As is true for CEVs, and for the same reasons, CUEs include extensive alarm systems
(e.g., door intrusion, emergency lights, smoke detector, power).
Local building permit requirements should be checked before beginning installation.
OSP Design Reference Manual, 4th edition
5-226
© 2007 BICSI®
Section 5: Spaces
Chapter 5: Pathways and Spaces
Marinas
Service at Marinas
Designers need to give special consideration to telecommunications services at marinas due to
unique conditions such as:
•
Changing water levels.
•
High moisture/humidity.
•
Severe weather (e.g., winds, waves, sun).
•
Salt.
•
Transience of boat owners.
•
Potential for deterioration of the distribution cable.
•
Difficulty in establishing a dependable and approved electrical grounding point.
Terms and Definitions
The following terms and definitions are used in this section:
•
Boat slip—The space reserved for a boat adjacent to a dock
•
Common element—A portion of a dock that is publicly accessible to all marina users
•
Condominium slip—A boat slip that is owned or subleased
•
Limited common element (LCE)—A portion of a dock that is accessible only to those boat
slips that it serves on either side
Docks with Floating Sections
Docks with floating sections are less desirable than fixed docks because of the increased risk
of strain and wear on all facilities, particularly during inclement weather. Floating docks are
usually found where water levels can change drastically. This condition should be taken into
consideration for locations that experience tides and seasonal changes.
To accommodate the movement of a floating dock to and from a shoreline, the following
arrangements should be used:
© 2007 BICSI®
•
Hose-reeling cable on a floating section
•
A point of connection at both ends of a dock section to ease adding or removing sections
of cable
•
Jack and plug arrangements for smaller installations that need only a few service cables
5-227
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 5: Spaces
Designating Specific Docks for Service
See Figures 5.105 and 5.106 for detail of a dock with a floating section and an example of a
marina.
A designer and an owner must designate specific docks in a marina for telecommunications
service. This eliminates the cost of placing facilities where demand may be minimal or
nonexistent. Generally, the demand for telecommunications at marinas is directly proportional
to the:
•
Client’s affluence.
•
Size of the boats moored.
•
Nontransient (e.g., permanent resident) population.
Precabling Boat Slips
Use Table 5.45 for guidelines when precabling boat slips.
Table 5.45
Precabling guidelines
If…
Then…
It is known in advance
that all or most of the
boat slips require
telecommunications
services
Precable each boat slip during construction of the dock. For
security, each run should be terminated in the patch panel
cross-connect at the dock master or marina office.
Fewer than 10 boat
slips are cabled
Run one- or two-pair cables from the boat slips to a distribution
terminal on the closest point of land.
If 10 or more boat
slips are cabled
Place distribution cable onto the dock and terminate in a
suitable cabinet or enclosure. Run service drop to each boat slip.
NOTE:
This minimizes the need for terminals on the dock where damage can occur due to
the harsh environment or vandalism (except for utility pedestals at every slip).
OSP Design Reference Manual, 4th edition
5-228
© 2007 BICSI®
Section 5: Spaces
Chapter 5: Pathways and Spaces
Using Mechanical Protection
All cable splices should be mechanically protected from hostile environment using:
•
Conduit.
•
Cable trays.
•
Weatherproof enclosures.
•
Other structures suited for harsh, outdoor conditions.
The support structures (i.e., pedestals) must be made of nonmetallic material to minimize
corrosion. A variety of weatherproof utility pedestals are available for terminating service
facilities at boat slips. These pedestals accommodate:
•
Electrical power.
•
Telecommunications.
•
CATV.
•
Water.
Protecting Cable, Conductors, and Terminals
Water-blocked cable on docks should be used. Terminals (if necessary) must be equipped with
a binding post and screw-down conductor lugs. Compound-filled protector caps must also be
used where corrosion is of particular concern. Industrial cabling (e.g., cables, connectivity) are
available for use and should be considered in harsh environments.
Choosing Conduit Size and Type
The type and size of conduit can be selected following these guidelines:
•
Use rigid nonmetallic conduit wherever possible.
•
Join the sections of rigid conduit with flexible duct where movement of a dock is probable.
•
Use minimum 21 mm (3/4 trade size) conduits for service cables to each slip.
The size of conduits for distribution cable varies depending on the:
© 2007 BICSI®
•
Pulling distance.
•
Bends.
•
Cable size.
5-229
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 5: Spaces
Bonding and Grounding (Earthing)
Electrical bonding and grounding (earthing) at marinas:
•
Requires close analysis.
•
Is addressed on a case-by-case basis.
The closest approved ground is on the nearest land unless a dock has metallic support
members extending into the lake or sea bottom, and electrical power service is grounded to
these supports.
This may require:
•
Locating station protectors on land where an approved ground is available.
•
Discussions and review with the:
–
Electrical contractor.
–
Electrical power utility company.
–
Marina owner.
–
Local electrical AHJ.
System Separation
The transient nature of most marina users makes telecommunications served through a
premises private branch exchange (PBX) impractical in many cases. However, a common
telecommunications conduit within a prefabricated dock section (see Figure 5.105) might be
the only available cabling medium:
•
In areas where direct local exchange service and public telephone service are provided by
different companies.
•
Where CATV is requested.
With coordination, simultaneous placement of both facilities instead of individual pull cords in
one duct is beneficial to both the telephone and CATV companies.
OSP Design Reference Manual, 4th edition
5-230
© 2007 BICSI®
Section 5: Spaces
Chapter 5: Pathways and Spaces
System Separation, continued
Figure 5.105
Modular floating dock layout
Pedestal
Main
Dock (common element)
Weatherproof
communications
jack
Finger dock
(limited common
element)
Slip A
Slip C
Prefabricated,
laminated,
fiberglass-enclosed
floating dock section
Slip B
Power conduit
Finger dock
(common element)
51 mm (2 in) PVC
communications conduit
Under
deck
cabling
101 mm (4 in) PVC
communications conduit
Waterproof splice
terminal chamber
in = Inch
mm = Millimeter
PVC = Polyvinyl chloride
© 2007 BICSI®
5-231
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
Section 5: Spaces
Condominium Slips
The marina (see Figure 5.106) usually owns the:
•
Serving finger dock to which each finger slip is attached.
•
Originating main dock (common elements).
When an individual boat slip is owned and subleased as a regular condominium, only the two
bordering boat slip owners can legally use a finger slip, a limited common element.
This arrangement raises questions about:
•
R/W and easement factors.
•
The possibility of seasonal subleasing of boat slips.
Prefabricated modular dock construction with built-in conduits and splice boxes neatly
structures full conductor and cable concealment while providing physical protection.
OSP Design Reference Manual, 4th edition
5-232
© 2007 BICSI®
Chapter 5: Pathways and Spaces
Condominium Slips, continued
Figure 5.106
Sample marina layout
Easement A (parking and utilities)
Easement B
(dock access
and utilities)
Main
feed
Terminal B
Pedestal B
Parking
Easement C
(pedestrian
and utilities)
Distribution feed
Pedestal A
Slips
Boat
launching
ramp
Floating
docks
Distribution
feed
Finger
dock
Terminal A
Easement D (dock
access and utilities)
Finger
dock
Each finger dock is a limited common
element (LCE), reserved for use by only
the units directly adjacent to it. For
example, the shaded finger dock (see
arrow) is reserved for use by slips D-4
and D-5 only. All other walkways are
common elements (CE).
D
D -3
-4
D -5
D -7
D -6
D 8
-9
C
E
D
Typical float detail
© 2007 BICSI®
5-233
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
References
American National Standards Institute. ANSI J-STD-607-A. Commercial Building
Grounding (Earthing) and Bonding Requirements for Telecommunications. Arlington, VA:
Telecommunications Industry Association, 2002.
American National Standards Institute/Telecommunications Industry Association/Electronic
Industries Alliance. ANSI/TIA/EIA-568-B.1. Commercial Building Telecommunications
Cabling Standard, Part 1: General Requirements. Arlington, VA: Telecommunications
Industry Association, 2001.
———. ANSI/TIA/EIA-568-B.2. Commercial Building Telecommunications Cabling
Standard, Part 2: Balanced Twisted-Pair Cabling Components. Arlington, VA:
Telecommunications Industry Association, 2001.
———. ANSI/TIA/EIA-568-B.3. Optical Fiber Cabling Components Standard. Arlington,
VA: Telecommunications Industry Association, 2000.
———. ANSI/TIA/EIA-569-B. Commercial Building Standard for Telecommunications
Pathways and Spaces. Arlington, VA: Telecommunications Industry Association, 2004.
———. ANSI/TIA/EIA-570-B. Residential Telecommunications Infrastructure Standard.
Arlington, VA: Telecommunications Industry Association, 2004.
———. ANSI/TIA/EIA-606-A. Administration Standard for Commercial
Telecommunications Infrastructure. Arlington, VA: Telecommunications Industry
Association, 2002.
———. ANSI/TIA/EIA-758-A. Customer-Owned Outside Plant Telecommunications
Infrastructure Standard. Arlington, VA: Telecommunications Industry Association, 2004.
AT&T Network Systems. Customer Education and Training. Outside Plant Engineering
Handbook. Edminster, NJ: AT&T, 1994.
Bell Atlantic Network Services. Outside Plant Engineering Reference Manual. South
Plainfield, NJ: Bell, 1987.
BICSI®. OSP 100. Introduction to Outside Plant. Tampa, FL: BICSI, 2007.
———. OSP 110. Outside Plant Cable Design. Tampa, FL: BICSI, 2007.
Common Ground Alliance. One-Call Systems International. Alexandria, VA: Common
Ground Alliance, 2003.
GTE. OSP Engineering. Volumes I and II. Dallas, TX: GTE Technical Documentation, 1991.
Institute of Electrical and Electronics Engineers, Inc.® 2007. National Electrical Safety
Code®. Piscataway, NJ: Institute of Electrical and Electronics Engineers, Inc., 2007.
OSP Design Reference Manual, 4th edition
5-234
© 2007 BICSI®
Chapter 5: Pathways and Spaces
Insulated Cable Engineers Association. ICEA S-83-596. Fiber Optic Premises Distribution
Cable. Carrollton, GA: Insulated Cable Engineers Association, 2001.
———. ANSI/ICEA S-84-608. Telecommunications Cable, Filled Polyolefin Insulated
Copper Conductor. Carrollton, GA: Insulated Cable Engineers Association, 2002.
———. ANSI/ICEA S-85-625. Aircore, Polyolefin Insulated,Copper Conductor
Telecommunications Cable. Carrollton, GA: Insulated Cable Engineers Association, 2002.
———. ANSI/ICEA S-90-661. Category 3, 5, & 5e Individually Unshielded Twisted-Pair
Indoor Cable for Use In General Purpose and LAN Communication Wiring Systems.
Carrollton, GA: Insulated Cable Engineers Association, 2000.
———. ANSI/ICEA S-98-688. Broadband Twisted-Pair Telecommunications Cable,
Aircore, Polyolefin Insulated Copper Conductors. Carrollton, GA: Insulated Cable
Engineers Association, 1997.
———. ANSI/ICEA S-99-689. Broadband Twisted-Pair Telecommunications Cable Filled
Polyolefin Insulated Copper Conductors. Carrollton, GA: Insulated Cable Engineers
Association, 1997.
———. ICEA S104-696. Standard for Indoor-Outdoor Optical Cable. Carrollton, GA:
Insulated Cable Engineers Association, 2003.
National Fire Protection Association, Inc. NFPA 70. National Electrical Code®, 2005 edition.
Quincy, MA: National Fire Protection Association, Inc., 2005.
———. NFPA 72®. National Fire Alarm Code®, 2007 edition. Quincy, MA: National Fire
Protection Association, Inc., 2007.
———. NFPA 75®. Standard for the Protection of Electronic Computer/Data Processing
Equipment. Quincy, MA: National Fire Protection Association, Inc., 2003.
———. NFPA 101®. Life Safety Code®. Quincy, MA: National Fire Protection Association,
Inc., 2006.
Underwriters Laboratories, Inc. ® UL 94. Test for Flammability of Plastic Materials for
Parts in Devices and Appliances. Northbrook, IL: Underwriters Laboratories, Inc., 2000.
———. UL 497. Standard for Protectors for Paired-Conductor Communications
Circuits. Northbrook, IL: Underwriters Laboratories, Inc., 2001.
———. UL 497A. Secondary Protectors for Communications Circuits. Northbrook, IL:
Underwriters Laboratories, Inc., 2001.
U.S. Department of the Army. FM 11-486-5. Telecommunications Engineering Outside
Plant, Telephone. Washington, DC: U.S. Department of the Army, 1978.
© 2007 BICSI®
5-235
OSP Design Reference Manual, 4th edition
Chapter 5: Pathways and Spaces
U.S. Department of Labor, Occupational Safety and Health Administration. Code of Federal
Regulations, Title 29, Part 1910: Occupational Safety and Health Standards. Washington,
DC: U.S. National Archives and Records Administration, Federal Register, 2001.
———. Code of Federal Regulations. Title 29, Part 1926: Safety and Health Regulations
for Construction. Washington, DC: U.S. National Archives and Records Administration,
Federal Register, 2003.
U.S. Government Printing Office. Bulletin 1751F-630. Design of Aerial Plant. Washington,
DC: Rural Utilities Service, 1996.
———. 1996. Bulletin 1751F-635. Aerial Plant Construction. Washington, DC: Rural
Utilities Service, 1996.
———. Bulletin 1751F-640. Design of Buried Plant-Physical Considerations. Washington,
DC: Rural Utilities Service, 1995.
———. Bulletin 1751F-641. Construction of Buried Plant. Washington, DC: Rural Utilities
Service, 1995.
———. Bulletin 1751F-642. Construction Route Planning of Buried Plant. Washington,
DC: Rural Utilities Service, 1995.
———. Bulletin 1751F-643. Underground Plant Design. Washington, DC: Rural Utilities
Service, 2002.
———. Bulletin 1751F-644. Underground Plant Construction. Washington, DC: Rural
Utilities Service, 2002.
———. Bulletin 1751F-650. Aerial Plant Guying and Anchoring. Washington, DC: Rural
Utilities Service, 1996.
———. Bulletin 1751F-815. Electrical Protection of Outside Plant. Washington, DC: Rural
Utilities Service, 1995.
———. Bulletin 1751F-642. Construction Route Planning of Buried Plant. Washington,
DC: Rural Utilities Service, 1995.
———. Bulletin 1751F-643. Underground Plant Design. Washington, DC: Rural Utilities
Service, 2002.
———. Bulletin 1751F-644. Underground Plant Construction. Washington, DC: Rural
Utilities Service, 2002.
———. Bulletin 1751F-650. Aerial Plant Guying and Anchoring. Washington, DC: Rural
Utilities Service, 1996.
———. Bulletin 1751F-815. Electrical Protection of Outside Plant. Washington, DC: Rural
Utilities Service, 1995.
OSP Design Reference Manual, 4th edition
5-236
© 2007 BICSI®
Chapter 6
Splicing Hardware
Chapter 6 analyzes the logistics and equipment for cable
splicing. Splicing locations, closures, hardware, connectors,
and methodologies for copper and optical fiber cables are
explained through theory, examples, and references.
Chapter 6: Splicing Hardware
Table of Contents
Splicing Enclosure ............................................................................... 6-1
Introduction ................................................................................................ 6-1
Splicing Locations ........................................................................................ 6-1
Closures for Twisted-Pair Cables ..................................................................... 6-4
Aerial Closures ............................................................................................. 6-5
Direct-Buried and Underground Closures .......................................................... 6-6
Optical Fiber Cable Closures ........................................................................... 6-7
Cabling Hardware Selection ........................................................................... 6-9
Optical Splice Closures ............................................................................. 6-9
Optical Distribution Centers/Housings ......................................................... 6-9
Transition/Indoor Splice Hardware ............................................................ 6-10
Transition Structure .............................................................................. 6-10
Outdoor Splice Hardware ........................................................................ 6-13
Connecting Hardware ................................................................................. 6-13
Design Considerations ................................................................................. 6-13
Splicing Connectors for Twisted-Pair Cable ..................................................... 6-15
Twisted-Pair Cable ..................................................................................... 6-18
Modular Splicing .................................................................................... 6-18
Splicing Methodology .................................................................................. 6-18
Splice Data ............................................................................................... 6-20
Testing .................................................................................................... 6-26
Waterproof Splicing .................................................................................... 6-26
Optical Fiber Cable ..................................................................................... 6-26
Splice Design ........................................................................................ 6-26
Optical Fiber Splicing Methods ..................................................................... 6-28
Fusion Splicing ..................................................................................... 6-29
Mechanical Splicing ............................................................................... 6-29
Mass Splicing ....................................................................................... 6-29
Splice Protection ....................................................................................... 6-30
Optical Fiber Cable Splicing Hardware Considerations ....................................... 6-31
Hardware Labeling ...................................................................................... 6-32
References ....................................................................................... 6-33
© 2007 BICSI®
6-i
OSP Design Reference Manual, 4th edition
Chapter 6: Splicing Hardware
Figures
Figure 6.1
Splice closures and covers ................................................................ 6-2
Figure 6.2
Splice closures ................................................................................ 6-3
Figure 6.3
Filled/direct-buried splice closure systems ........................................... 6-6
Figure 6.4
Optical fiber closure ......................................................................... 6-7
Figure 6.5
Underground to building transition .................................................... 6-10
Figure 6.6
Underground to direct-buried transition ............................................. 6-11
Figure 6.7
Direct-buried to building transition .................................................... 6-12
Figure 6.8
Example of IDC connection .............................................................. 6-15
Figure 6.9
Types of splices ............................................................................ 6-15
Figure 6.10 Example of single pair splice connectors and modules .......................... 6-16
Figure 6.11 Example of multipair splice connectors and modules ............................ 6-17
Figure 6.12 Inline splice .................................................................................. 6-18
Figure 6.13 Foldback splice ............................................................................. 6-19
Figure 6.14 Completed two-bank splice ............................................................. 6-19
Figure 6.15 Examples of splices required due to cable routing ............................... 6-26
Figure 6.16 Splice tray examples ...................................................................... 6-31
Tables
Table 6.1
Aerial closure size ............................................................................ 6-5
Table 6.2
Direct-buried/underground closure size ............................................... 6-7
Table 6.3
Two-bank fold-back splice data ....................................................... 6-20
Table 6.4
26 AWG two-bank straight splice ..................................................... 6-21
Table 6.5
26 AWG three-bank straight splice ................................................... 6-22
Table 6.6
26 AWG four-bank straight splice ..................................................... 6-23
Table 6.7
26 AWG two-bank apparatus splice .................................................. 6-24
OSP Design Reference Manual, 4th edition
6-ii
© 2007 BICSI®
Chapter 6: Splicing Hardware
Splicing Enclosure
Introduction
Cabling hardware is used in outside plant (OSP) to enclose splices. They are more commonly
known as splice cases or closures. Cabling hardware is distinct from connecting hardware in
that it attaches to the sheath, whereas connecting hardware connects to the conductors or
optical fiber strands. The connecting hardware and the cabling hardware should complement
each other, but many combinations of either will establish the connectivity required to maintain
a high-quality transmission path.
Splicing Locations
Cabling hardware can be constructed of metallic or nonmetallic materials and can be found in
aerial, underground, and direct-buried construction, such as:
•
Pedestals and cabinets.
•
Handholes (HHs). New splices shall not be placed in HHs.
•
Maintenance holes (MHs).
•
Poles.
•
Support strands.
•
Walls.
•
Vaults.
Splice closures are used in both copper and optical fiber applications and can be pressurized or
nonpressurized. They typically:
© 2007 BICSI®
•
Secure and protect cable and splices.
•
Provide strain relief.
•
Allow for reentry.
6-1
OSP Design Reference Manual, 4th edition
Chapter 6: Splicing Hardware
Splicing Locations, continued
See Figure 6.1 for three representations of splice closures.
Figure 6.1
Splice closures and covers
Closure
cover
Closure
cover
Closure
cover
Splice closure
Splice closure
Splice closure
Splice closures are classified according to the configuration of cables that enter the closure,
such as:
•
Straight—Provisions are made for only one cable to enter each end of the closure.
•
Branch—Provisions are made for two or more cables to enter one end or both ends of the
closure.
•
Butt—Provisions are made for two or more cables to enter one end of the closure and no
cables enter the other end.
•
Universal—Provisions are made for adapters that allow multiple cables to enter one end
or both ends of the closure. This type of splice closure is typically referred to as a vault
closure.
Manufacturer specifications should be consulted for splice closure capacity.
OSP Design Reference Manual, 4th edition
6-2
© 2007 BICSI®
Chapter 6: Splicing Hardware
Splicing Locations, continued
Splice closures (see Figure 6.2) are specifically designed for an intended application.
Figure 6.2
Splice closures
Branch Splice Configuration
Cable
Cable
Splice case
Cable
Butt Splice Configuration
Cable
Splice case
Cable
Straight Splice Configuration
Cable
Cable
Splice case
Vault Closure
Entrance
cable
© 2007 BICSI®
Listed
fire rated
splice case
Tip cables
to entrance
facility room
6-3
OSP Design Reference Manual, 4th edition
Chapter 6: Splicing Hardware
Closures for Twisted-Pair Cables
Closures for twisted-pair cables are used to protect splices from mechanical and
environmental hazards. These can be used in:
•
Aerial applications (e.g., on poles, strands, and building exteriors).
•
Direct-buried applications.
•
Underground applications (e.g., MHs, vaults).
•
Aboveground pedestals fed by aerial, underground, or buried cables.
•
In-building applications (e.g., fire resistant transition, vault splices).
Closures are reenterable and may be watertight or vented. However, the encapsulant choice
may preclude splice reentry. Copper closures are capable of:
•
Storing and organizing splices (whether individually spliced or mass spliced).
•
Providing grounding (earthing) and bonding facilities.
OSP Design Reference Manual, 4th edition
6-4
© 2007 BICSI®
Chapter 6: Splicing Hardware
Aerial Closures
Aerial closures are housings used for splicing, grounding (earthing), and bonding aerial cables.
They may be equipped with terminal blocks and fusible-link stub cables that are housed in
separate chambers to allow for the termination of service wires.
Aerial closures typically support strand mounted and do not affect the integrity of the support
strand. They can be used to maintain the bond continuity of the splice point along the cable.
Additionally, they can be pole- or wall- mounted.
Aerial closures are available in many sizes, based on the size and number of cables entering
and exiting the closure. Table 6.1 is representative of the range of sizes available; however,
the OSP designer should consult manufacturers’ specifications for the exact capacities of their
closures.
Table 6.1
Aerial closure size
Type
Length
Cable
Diameter
Sheath
Opening
Splice
Diameter
Straight
660 mm
(26 in)
0.0–30.5 mm
(0.0–1.2 in)
483 mm
(19 in)
61 mm
(2.4 in)
Straight
660 mm
(26 in)
25–46 mm
(1–1.8 in)
483 mm
(19 in)
114 mm
(4.5 in)
Straight
660 mm
(26 in)
38–64 mm
(1.5–2.5 in)
483 mm
(19 in)
163 mm
(6.4 in)
Branch
660 mm
(26 in)
0.0–30.5 mm
(0.0–1.2 in)
483 mm
(19 in)
114 mm
(4.5 in)
Branch
660 mm
(26 in)
25–56 mm
(1–2.2 in)
483 mm
(19 in)
163 mm
(6.4 in)
Branch
660 mm
(26 in)
51–76 mm
(2–3 in)
483 mm
(19 in)
203 mm
(8 in)
in
mm
© 2007 BICSI®
=
=
Inch
Millimeter
6-5
OSP Design Reference Manual, 4th edition
Chapter 6: Splicing Hardware
Direct-Buried and Underground Closures
Direct-buried/underground closures provide housing for splices, grounding (earthing), and
bonding. These closures are designed to restore the sheath’s mechanical integrity and
electrical properties. Cables may enter these closures from one or both ends.
To protect splices from moisture when air-pressure systems are not used, direct-buried/
underground closures should be filled with an encapsulant after splicing operations are
complete to make them watertight (see Figure 6.3). Reenterable encapsulant is removable
from the splice closure to allow future splicing operations.
Figure 6.3
Filled/direct-buried splice closure systems
OSP Design Reference Manual, 4th edition
6-6
© 2007 BICSI®
Chapter 6: Splicing Hardware
Direct-Buried and Underground Closures, continued
Direct-buried/underground closures are available in many sizes, based on the size and number
of cables entering and exiting the closure. Table 6.2 is representative of the range of sizes
available; however, the designer should check with the manufacturer for the exact capacities
of their closures. Certain closures will be pressurized when the spliced cables are part of an
air-pressure system.
Table 6.2
Direct-buried/underground closure size
Length
Cable
Diameter
Sheath
Opening
Splice
Diameter
533 mm (21 in)
13–41 mm (0.5–1.6 in)
305 mm (12 in)
58 mm (2.3 in)
737 mm (29 in)
20–66 mm (0.8–2.6 in)
508 mm (20 in)
84 mm (3.3 in)
30.5–86 mm (1.2–3.4 in)
914 mm (36 in)
135 mm (5.3 in)
1143 mm (45 in)
in =
mm =
Inch
Millimeter
Optical Fiber Cable Closures
Closures for optical fiber cables are used to protect splices from mechanical and environmental hazards (see Figure 6.4). Closures are reenterable and may be watertight or vented.
However, the encapsulant choice may preclude splice reentry. They are used:
•
On poles, strands, and buildings.
•
In underground installations, direct-buried installations, and aboveground pedestals.
Figure 6.4
Optical fiber closure
Service loop
Splice tray
© 2007 BICSI®
6-7
OSP Design Reference Manual, 4th edition
Chapter 6: Splicing Hardware
Optical Fiber Cable Closures, continued
Optical fiber closures are capable of:
•
Storing and organizing optical fiber strands.
•
Storing and organizing splices (whether individually or mass spliced) through the use of
splicing trays.
•
Providing grounding (earthing) and bonding facilities.
•
Maintaining minimum bend radius for the individual optical fiber strands.
•
Ensuring zero light loss by restricting cable movement.
NOTE:
Consult manufacturer specifications for splice closure capacity.
OSP Design Reference Manual, 4th edition
6-8
© 2007 BICSI®
Chapter 6: Splicing Hardware
Cabling Hardware Selection
Optical Splice Closures
Splice closure selection is based mainly on the quantities of optical fibers and cables at a splice
point. Splice closures can accommodate both high and low optical fiber-count splice points.
The standard maximum number of cable entries is four, but up to eight cable entries are
possible. Closures can either be factory- or field-drilled to a specific cable diameter or can be
ported for easy cable entry. Many closures are available with an inner closure to keep
encapsulant out of the splice trays when the closure is encapsulated. The use of an inner
closure also simplifies the reentry process.
Splice closures are designed for aerial, buried, or underground applications. These closures
can usually be installed quickly with ordinary tools.
Optical Distribution Centers/Housings
Distribution centers are typically available in either 12- or 24-strand optical fiber
configurations. They can be placed in an exposed environment as they are typically rated for
outdoor applications.
These units can be mounted to a utility pole. A bracket is provided for this application. The
units can also be mounted to an outside wall or cable tray and are available with either two
51 mm (2 in) conduit fittings or a “no holes” version for field drilling.
Distribution centers are designed for use with outdoor-rated conduit. They should not be
placed in an environment where water will immerse the unit. Some housings are designed to
be mounted to a wall or cable tray in a semi-sheltered environment. More specifically, they
should have an overhead roof. These housings are also available with either two 51 mm (2 in)
conduit fittings or are available in a “no holes” version for field drilling.
Both the distribution centers and the housings will accommodate splice trays and pigtails or as
a direct termination point. These distribution centers are ideally suited for use in an indoor/
outdoor industrial environment where data acquisition or video cameras are needed.
© 2007 BICSI®
6-9
OSP Design Reference Manual, 4th edition
Chapter 6: Splicing Hardware
Cabling Hardware Selection, continued
Transition/Indoor Splice Hardware
A transition splice point shall be required when the termination point is greater than 15.2 m
(50 ft) from the building entrance and the unlisted campus backbone loose-tube cable cannot
be installed in a properly rated conduit. The campus backbone cable can be spliced to a
building backbone cable to meet local standards for fire-rated cables. Additionally, inside splice
hardware can be used to route optical fiber circuits to different locations when a patch panel
is not desired, or to splice pigtails to terminate optical fibers versus direct connectorization.
A transition splice is typically located near the building entrance point. Wall-mountable
hardware is generally required; however, rack-mountable products may be used, specifically
when splicing pigtails for termination. If armored cable is used, the grounding of metallic cable
elements shall be required. The hardware housing may be required to strain relieve several
cables.
Transition Structure
In some situations, construction may transition from one type to another. Examples of such
transitions appear in Figures 6.5 through 6.7.
Figure 6.5
Underground to building transition
Building
Backboard
Protector
Cable
Splice
case
Subsidiary
conduit
Conduit
Underground
cable
Conduit
MH
MH = Maintenance hole
OSP Design Reference Manual, 4th edition
6-10
© 2007 BICSI®
Chapter 6: Splicing Hardware
Cabling Hardware Selection, continued
Figure 6.6
Underground to direct-buried transition
Pedestal/splice closure
Buried cable
Subsidiary conduit
Buried cable
Conduit
Conduit
Underground cable
MH
Splice case
MH = Maintenance hole
© 2007 BICSI®
6-11
OSP Design Reference Manual, 4th edition
Chapter 6: Splicing Hardware
Cabling Hardware Selection, continued
Figure 6.7
Direct-buried to building transition
Terminal protector
Pedestal/splice closure
Grade
Sleeve
Direct-buried cable
Protector
Backboard
Sleeve through
building wall
Cable
Pedestal/splice closure
Grade
Direct-buried cable
OSP Design Reference Manual, 4th edition
6-12
© 2007 BICSI®
Chapter 6: Splicing Hardware
Cabling Hardware Selection, continued
Outdoor Splice Hardware
The outdoor hardware consists of splice closures, wall- and pole-mountable distribution
centers, and pedestal-mountable cross-connects. These units provide environmental protection
for splices, connectors, and jumpers in the OSP environment, often required in industrial and
other special applications. Although products used outdoors should be designed for that
environment, the end user may also use indoor-rated hardware outdoors if it is placed inside
an enclosure that has a National Electrical Manufacturers Association (NEMA®) rating
suitable for the environment. This technique is also used in industrial environments that use
harsh or caustic chemicals that could cause failure to standard indoor or outdoor hardware.
Field splices occur in aerial, duct, direct-buried, or aboveground locations. The termination or
distribution center must provide mechanical and environmental protection in the OSP.
If a splice closure is to be encapsulated, it should be reenterable to allow for cable additions or
splicing plan changes.
Connecting Hardware
OSP splices generally occur in aerial, direct-buried, aboveground, or underground locations.
The termination or distribution center must provide mechanical and environmental protection.
Cable splice locations and other splicing details should be specified in work order prints.
Design Considerations
Whether the transmission medium is twisted-pair or optical fiber cable, the designer should
carefully consider the amount and location of the splices that result. The goal is to minimize
splices, since they may be a source of a disproportionate amount of subsequent troubles.
Additionally, labor is usually a more expensive factor than material in a design. At the cost of
additional material, avoiding splices may be the wiser economic choice. When a splice cannot
be reasonably avoided, the designer should avoid creating a future maintenance problem. This
can be achieved by careful splicing and choosing splicing tools and techniques that are reliable,
regardless of the transmission medium.
When constrained duct or conduit space prevents the use of multiple sheaths, a splice should
be used to consolidate the sheaths into one higher pair or optical fiber-count sheath. As many
cables as possible should be combined at a single splice point, since the incremental cost per
additional conductor or optical fiber spliced is lower than the cost for splicing at different
locations. It is important to analyze the entire system when planning splice points. For
example, if a planned cross-connect is near an MH that is being considered for a splice point,
cables may need to be routed to the cross-connect to combine the splice point with the
termination point. This can result in substantial labor cost savings.
© 2007 BICSI®
6-13
OSP Design Reference Manual, 4th edition
Chapter 6: Splicing Hardware
Design Considerations, continued
The designer must determine splicing configurations used for distributing cable counts in the
aerial, direct-buried, and underground network. Many design issues for splicing configurations
should be considered by the designer, including:
•
Will this splice configuration have to be opened in the future?
•
Can an additional cable be placed into this splice configuration without major
rearrangements?
•
Will a stub cable between splice configurations be required? If so, what type, size, and
cable count?
•
What type of splice configuration will be used?
•
Should spare facilities be allocated in the stub cable?
•
Is pair loading/load stubs required?
For schematic representation of various splice configurations, see Chapter 10: Design
Documentation.
The use of any particular type of configuration should be determined by the:
•
Geographic area where the splice configuration has to be placed.
•
Number of physical cables and related cable counts that have to be spliced and
redirected.
•
Space that is available to construct this splice configuration.
•
Safety related to working with the configuration.
Critical considerations in designing splice configurations are to design a splice that may:
•
Require very little future reentry.
•
Be reentered to change splice counts easily.
•
Accept an additional stub cable, if required.
Most of the difficulties encountered in OSP are manmade. Reentering splices invites difficulty.
The designer should minimize the potential for requiring reentry at the same time the initial
design is developed. If this cannot be avoided, any reentry should keep manipulation to a
minimum.
OSP Design Reference Manual, 4th edition
6-14
© 2007 BICSI®
Chapter 6: Splicing Hardware
Splicing Connectors for Twisted-Pair Cable
The splicing operation can be done with one of two widely used types of equipment—MS2 or
Type 710. Both have insulation displacement connectors (IDCs [see Figure 6.8]).
Figure 6.8
Example of IDC connection
Direction of
insertion
Conductor
Insulation
View from top
IDC
IDC = Insulation displacement connector
Most twisted-pair cable splicing is performed with modular and/or discrete connectors. There
are three general splicing methods: in-line, butt, and branch (see Figure 6.9).
These connectors are used for OSP or intrabuilding use and, depending on the manufacturer,
accommodate 19 American wire gauge (AWG [0.91 mm (0.036 in)]) to 28 AWG [0.32 mm
(0.013 in)] wire.
In addition, these connectors are available in several pair sizes (e.g., 1-, 5-, 10-, 25-pair), and
should be placed in 1-, 2-, 3-, or 4-bank configurations within the splice. Testing the cable and
the splice should be performed either during or after construction.
Figure 6.9
Types of splices
In-line
In
Out
Butt
In
Out
Branch
Out
In
Out
Out
© 2007 BICSI®
6-15
OSP Design Reference Manual, 4th edition
Chapter 6: Splicing Hardware
Splicing Connectors for Twisted-Pair Cable, continued
Single connectors (see Figure 6.10):
•
Are available in designs capable of terminating two or three conductors.
•
Can be filled or nonfilled.
•
Accept different gauge wires.
•
Require minimum setup time.
Figure 6.10
Example of single pair splice connectors and modules
Full pair in-line splice connector
Butt splice connector
Box tap splice connector
Multipurpose splice connector
OSP Design Reference Manual, 4th edition
6-16
© 2007 BICSI®
Chapter 6: Splicing Hardware
Splicing Connectors for Twisted-Pair Cable, continued
Multipair splicing modules (see Figure 6.11):
•
Splice up to 25 pairs.
•
Cut off excess conductor as connection is being made.
•
Require an equipment investment.
•
Produce higher productivity once the setup is complete.
Figure 6.11
Example of multipair splice connectors and modules
Write-on surface
Cover
Body
Base
For the splicing operation to be successful, the designer must consider some key factors—the
closure should be lightweight, compact, and watertight.
When the closure is installed, it must be properly supported, grounded, and tested for air leaks
according to manufacturer recommendations.
Labels must also be affixed to all cables entering the splice, indicating cable number and paircounts. Care must be taken to clearly designate the in and out for the spliced cables.
© 2007 BICSI®
6-17
OSP Design Reference Manual, 4th edition
Chapter 6: Splicing Hardware
Twisted-Pair Cable
Modular Splicing
A major planning consideration for module type designs is the planning of reentry into these
splices. Most module types are available in:
•
Dry versions for pressurized, vault, or inside splice applications.
•
Encapsulated versions for moisture resistance in free-breathing aerial splice closures.
•
Dry versions with a sealant box for maximum moisture protection in nonpressurized
plastic insulated conductor (PIC) splicing applications.
Dry module types are available in flame-retardant versions for vault and inside splice
applications. All fire-retardant modules must meet the Underwriters Laboratories Inc.®
(UL®) 94, Test for Flammability of Plastic Materials for Parts in Devices and
Appliances, requirements and possess an oxygen index of 28 or greater per American
Society for Testing and Materials (ASTM®) D2863, Standard Test Method for Measuring
the Minimum Oxygen Concentration to Support Candle-Like Combustion of Plastics
(Oxygen Index).
Splicing reentries determine how many module banks will be required in a splice. Splice bank
configurations and splice types listed on the work print at each splice location using a coding
system helps convey required configurations needed.
NOTE:
Code always starts with a number representing the number of banks in a splice.
One of three configurations will be used.
Splicing Methodology
The primary splicing methods within cases are:
•
Inline splicing method—Wire is placed in a straight-line arrangement. This method is not
designed to be rearranged and should have minimum handling. See Figure 6.12.
Figure 6.12
Inline splice
OSP Design Reference Manual, 4th edition
6-18
© 2007 BICSI®
Chapter 6: Splicing Hardware
Splicing Methodology, continued
•
Foldback splicing method—Conductors are folded into the splice to provide slack in the
conductors for maintenance, rearrangement, or transfer of conductors. See Figure 6.13.
•
Two-bank splicing method—Binder groups are arranged into groups or banks (see
Figure 6.14). This allows high pair-count copper splices to maintain a smaller diameter
relative to the spliced cable diameter. As racking space in MHs could be at a premium,
this also permits a splice closure of smaller diameter to be used.
Figure 6.13
Foldback splice
Figure 6.14
Completed two-bank splice
© 2007 BICSI®
6-19
OSP Design Reference Manual, 4th edition
Chapter 6: Splicing Hardware
Splice Data
Data in tables 6.3 through 6.7 was obtained from splices utilizing the MS2 modular splicing
method. When the bundle’s outside diameter (OD) is close to the splice case or sleeves inside
diameter (ID), the designer must use extra care not to exceed the maximum OD. If sealant
boxes are used, increase values by approximately 25 percent.
Table 6.3
Two-bank fold-back splice data
Recommended
Splice Opening
mm (in)
In-Line
Splice Diameter
mm (in)
Pair
Count
AWG
mm (in )
400
26 [0.41 (0.016)]
24 [0.51 (0.020)]
22 [0.64 (0.025)]
600
26 [0.41 (0.016)]
24 [0.51 (0.020)]
22 [0.64 (0.025)]
81 (3.2)
99 (3.9)
122 (4.8)
900
26 [0.41 (0.016)]
24 [0.51 (0.020)]
22 [0.64 (0.025)]
432 (17)
104 (4.1)
127 (5.0)
147 (5.8)
1200
26 [0.41 (0.016)]
24 [0.51 (0.020)]
432 (17)
432 (17)
119 (4.7)
127 (5.0)
1500
26 [0.41 (0.016)]
483 (19)
137 (5.4)
432 (17)
71 (2.8)
89 (3.5)
102 (4.0)
24 [0.51 (0.020)]
145 (5.7)
1800
26 [0.41 (0.016)]
24 [0.51 (0.020)]
152 (6.0)
160 (6.3)
2100
26 [0.41 (0.016)]
24 [0.51 (0.020)]
157 (6.2)
170 (6.7)
2400
26 [0.41 (0.016)]
165 (6.5)
2700
26 [0.41 (0.016)]
183 (7.2)
3000
26 [0.41 (0.016)]
483 (19)
193 (7.6)
3600
26 [0.41 (0.016)]
483 (19)
203 (8.0)
AWG = American wire gauge
in = Inch
m m = Millimeter
OSP Design Reference Manual, 4th edition
6-20
© 2007 BICSI®
Chapter 6: Splicing Hardware
Splice Data, continued
Table 6.4
26 AWG two-bank straight splice
Main
Cable
Pair
Count
Zero
mm (in)
100
mm (in)
100
33.0 (1.3)
43.2 (1.7)
200
48.0 (1.9)
53.0 (2.1)
61.0 (2.4)
300
56.0 (2.2)
66.0 (2.6)
69.0 (2.7)
76.0 (3.0)
400
66.0 (2.6)
73.7 (2.9)
76.0 (3.0)
81.0 (3.2)
94.0 (3.7)
600
79.0 (3.1)
86.0 (3.4)
89.0 (3.5)
96.5 (3.8)
104.0 (4.1)
111.8 (4.4)
900
96.5 (3.8)
101.0 (4.0)
106.7 (4.2)
111.8 (4.4)
119.0 (4.7)
124.5 (4.9)
135.0 (5.3)
1100
101.0 (4.0)
111.8 (4.4)
116.8 (4.6)
122.0 (4.8)
127.0 (5.0)
129.5 (5.1)
142.2 (5.6)
1200
106.7 (4.2)
114.0 (4.5)
122.0 (4.8)
127.0 (5.0)
132.1 (5.2)
135.0 (5.3)
147.0 (5.8)
160.0 (6.3)
1500
124.5 (4.9)
129.5 (5.1)
137.0 (5.4)
142.2 (5.6)
145.0 (5.7)
152.0 (6.0)
160.0 (6.3)
170.0 (6.7)
1800
137.0 (5.4)
142.2 (5.6)
150.0 (5.9)
152.0 (6.0)
155.0 (6.1)
163.0 (6.4)
168.0 (6.6)
180.3 (7.1)
2100
147.0 (5.8)
155.0 (6.1)
160.0 (6.3)
163.0 (6.4)
165.0 (6.5)
172.7 (6.8)
183.0 (7.2)
190.5 (7.5)
2400
157.0 (6.2)
165.0 (6.5)
170.0 (6.7)
172.7 (6.8)
175.3 (6.9)
183.0 (7.2)
193.0 (7.6)
200.7 (7.9)
2700
168.0 (6.6)
178.0 (7.0)
180.3 (7.1)
183.0 (7.2)
185.4 (7.3)
193.0 (7.6)
198.1 (7.8)
208.3 (8.2)
3000
178.0 (7.0)
188.0 (7.4)
190.5 (7.5)
193.0 (7.6)
195.6 (7.7)
203.0 (8.0)
210.8 (8.3)
218.4 (8.6)
3600
195.6 (7.7)
208.3 (8.2)
210.8 (8.3)
213.4 (8.4)
215.9 (8.5)
221.0 (8.7)
229.0 (9.0)
231.1 (9.1)
Main
Cable
Pair
Count
1500
mm (in)
Number of Pair Bridged
1800
2100
2400
mm (in)
mm (in)
mm (in)
2700
mm (in)
3000
mm (in)
1500
178.0 (7.0)
1800
185.4 (7.3)
193.0 (7.6)
2100
193.0 (7.6)
200.7 (7.9)
210.8 (8.3)
2400
200.7 (7.9)
208.3 (8.2)
218.4 (8.6)
223.5 (8.8)
2700
210.8 (8.3)
218.4 (8.6)
226.1 (8.9)
238.8 (9.4)
243.8 (9.6)
3000
218.4 (8.6)
226.1 (8.9)
236.2 (9.3)
248.9 (9.8)
256.5 (10.1)
3600
233.7 (9.2)
243.8 (9.6)
251.5 (9.9)
261.6 (10.3)
in =
mm =
200
mm (in)
Number of Pair Bridged
300
400
600
mm (in)
mm (in)
mm (in)
900
mm (in)
1200
mm (in)
269.2 (10.6) 276.9 (10.9)
Inch
Millimeter
NOTES: Zero is straight splice measurement in inline configuration.
For 22 AWG [0.64 mm (0.025 in)] conductors, increase values by 25 percent.
For 24 AWG [0.51 mm (0.020 in)] conductors, increase values by 12 percent.
If sealant boxes are used, increase values approximately 25 percent.
© 2007 BICSI®
6-21
OSP Design Reference Manual, 4th edition
Chapter 6: Splicing Hardware
Splice Data, continued
Table 6.5
26 AWG three-bank straight splice
Main
Cable
Pair
Count
Zero
mm (in)
100
mm (in)
300
46.0 (1.8)
53.0 (2.1)
61.0 (2.4)
69.0 (2.7)
600
66.0 (2.6)
71.0 (2.8)
79.0 (3.1)
84.0 (3.3)
86.0 (3.4)
94.0 (3.7)
900
84.0 (3.3)
86.0 (3.5)
96.5 (3.8)
101.0 (4.0)
104.0 (4.1)
109.2 (4.3)
122.0 (4.8)
1200
99.0 (3.9)
104.0 (4.1)
109.2 (4.3)
114.0 (4.5)
119.0 (4.7)
127.0 (5.0)
139.7 (5.5)
145.0 (5.7)
1500
114.0 (4.5)
116.8 (4.6)
119.0 (4.7)
124.5 (4.9)
129.5 (5.1)
139.7 (5.5)
150.0 (5.9)
160.0 (6.3)
1800
129.5 (5.1)
132.1 (5.2)
135.0 (5.3)
137.0 (5.4)
139.7 (5.5)
150.0 (5.9)
160.0 (6.3)
170.0 (6.7)
2100
139.7 (5.5)
142.2 (5.6)
145.0 (5.7)
147.0 (5.8)
150.0 (5.9)
160.0 (6.3)
170.0 (6.7)
178.0 (7.0)
2400
150.0 (5.9)
152.0 (6.0)
155.0 (6.1)
157.0 (6.2)
160.0 (6.3)
168.0 (6.6)
178.0 (7.0)
185.4 (7.3)
2700
157.0 (6.2)
160.0 (6.3)
163.0 (6.4)
165.0 (6.5)
168.0 (6.6)
175.3 (6.9)
183.0 (7.2)
193.0 (7.6)
3000
165.0 (6.5)
168.0 (6.6)
170.0 (6.7)
172.7 (6.8)
175.3 (6.9)
183.0 (7.2)
190.5 (7.5)
200.7 (7.9)
3600
175.3 (6.9)
178.0 (7.0)
180.3 (7.1)
183.0 (7.2)
185.4 (7.3)
193.0 (7.6)
200.7 (7.9)
210.8 (8.3)
Main
Cable
Pair
Count
1500
mm (in)
1800
mm (in)
Number of Pair Bridged
2100
2400
2700
mm (in)
mm (in)
mm (in)
3000
mm (in)
1500
168.0 (6.6)
1800
178.0 (7.0)
185.4 (7.3)
2100
188.0 (7.4)
195.6 (7.7)
198.1 (7.8)
2400
195.6 (7.7)
203.0 (8.0)
205.7 (8.1)
213.4 (8.4)
2700
203.0 (8.0)
210.8 (8.3)
215.9 (8.5)
221.0 (8.7)
223.5 (8.8)
3000
208.3 (8.2)
218.4 (8.6)
221.0 (8.7)
229.0 (9.0)
231.1 (9.1)
236.2 (9.3)
3600
218.4 (8.6)
226.1 (8.9)
233.7 (9.2)
238.8 (9.4)
241.3 (9.5)
246.4 (9.7)
Number of Pair Bridged
200
300
400
mm (in)
mm (in)
mm (in)
600
mm (in)
900
mm (in)
1200
mm (in)
in = Inch
m m = Millimeter
NOTES: Zero is straight splice measurement in inline configuration.
For 22 AWG [0.64 mm (0.025 in)] conductors, increase values by 25 percent.
For 24 AWG [0.51 mm (0.020 in)] conductors, increase values by 12 percent.
If sealant boxes are used, increase values approximately 25 percent.
OSP Design Reference Manual, 4th edition
6-22
© 2007 BICSI®
Chapter 6: Splicing Hardware
Splice Data, continued
Table 6.6
26 AWG four-bank straight splice
Main
Cable
Pair
Count
Zero
mm (in)
100
mm (in)
400
51.0 (2.0)
53.0 (2.1)
56.0 (2.2)
58.4 (2.3)
64.0 (2.5)
600
58.0 (2.3)
64.0 (2.5)
66.0 (2.6)
69.0 (2.7)
73.7 (2.9)
79.0 (3.1)
900
71.0 (2.8)
76.0 (3.0)
79.0 (3.1)
81.0 (3.2)
86.0 (3.4)
91.4 (3.6)
99.1 (3.9)
1200
81.0 (3.2)
86.0 (3.4)
89.0 (3.5)
91.4 (3.6)
96.5 (3.8)
101.0 (4.0)
109.2 (4.3)
119.0 (4.7)
1500
94.0 (3.7)
96.5 (3.8)
99.0 (3.9)
101.0 (4.0)
106.7 (4.2)
109.2 (4.3)
119.0 (4.7)
129.5 (5.1)
1800
106.7 (4.2)
106.7 (4.2)
109.2 (4.3)
111.8 (4.4)
116.8 (4.6)
122.0 (4.8)
129.5 (5.1)
137.0 (5.4)
2100
116.8 (4.6)
116.8 (4.6)
119.0 (4.7)
122.0 (4.8)
127.0 (5.0)
132.1 (5.2)
142.2 (5.6)
147.0 (5.8)
2400
124.5 (4.9)
124.5 (4.9)
129.5 (5.1)
132.1 (5.2)
137.0 (5.4)
142.2 (5.6)
150.0 (5.9)
155.0 (6.1)
2700
137.2 (5.4)
137.0 (5.4)
139.7 (5.5)
142.2 (5.6) 145.08 (5.7)
150.0 (5.9)
157.0 (6.2)
163.0 (6.4)
3000
145.0 (5.7)
145.0 (5.7)
147.0 (5.8)
150.0 (5.9)
152.0 (6.0)
157.0 (6.2)
165.0 (6.5)
170.0 (6.7)
3600
157.0 (6.2)
160.0 (6.3)
163.0 (6.4)
165.0 (6.5)
168.0 (6.6)
172.7 (6.8)
178.0 (7.0)
185.4 (7.3)
Main
Cable
Pair
Count
1500
mm (in)
Number of Pair Bridged
1800
2100
2400
mm (in)
mm (in)
mm (in)
2700
mm (in)
3000
mm (in)
1500
135.0 (5.3)
1800
145.0 (5.7)
155.0 (6.1)
2100
155.0 (6.1)
163.0 (6.4)
168.0 (6.6)
2400
163.0 (6.4)
170.0 (6.7)
175.3 (6.9)
178.0 (7.0)
2700
170.0 (6.7)
178.0 (7.0)
183.0 (7.2)
188.0 (7.4)
190.5 (7.5)
3000
178.0 (7.0)
185.4 (7.3)
190.5 (7.5)
198.1 (7.8)
200.7 (7.9)
208.3 (8.2)
3600
193.0 (7.6)
200.7 (7.9)
208.3 (8.2)
218.4 (8.6)
226.1 (8.9)
238.8 (9.4)
in =
mm =
Number of Pair Bridged
200
300
400
600
mm (in)
mm (in)
mm (in)
mm (in)
900
mm (in)
1200
mm (in)
Inch
Millimeter
NOTES: Zero is straight splice measurement in inline configuration.
For 22 AWG [0.64 mm (0.025 in)] conductors, increase values by 25 percent.
For 24 AWG [0.51 mm (0.020 in)] conductors, increase values by 12 percent.
If sealant boxes are used, increase values approximately 25 percent.
© 2007 BICSI®
6-23
OSP Design Reference Manual, 4th edition
Chapter 6: Splicing Hardware
Splice Data, continued
Table 6.7
26 AWG two-bank apparatus splice
Main
Cable
Pair
Count
1500
mm (in)
Number of Pair Bridged
2100
2400
mm (in)
mm (in)
1800
mm (in)
2700
mm (in)
3000
mm (in)
50
33.0 (1.3)
41.0 (1.6)
100
41.0 (1.6)
48.0 (1.9)
58.4 (2.3)
200
58.0 (2.3)
66.0 (2.6)
69.0 (2.7)
84.0 (3.3)
300
69.0 (2.7)
79.0 (3.1)
84.0 (3.3)
96.5 (3.8)
106.7 (4.2)
400
79.0 (3.1)
86.0 (3.4)
96.5 (3.8)
106.7 (4.2)
116.8 (4.6)
132.1 (5.2)
600
94.0 (3.7)
104.0 (4.1)
111.8 (4.4)
122.0 (4.8)
132.1 (5.2)
147.0 (5.8)
900
122.0 (4.8)
127.0 (5.0)
132.1 (5.2)
142.2 (5.6)
150.0 (5.9)
160.0 (6.3)
1200
137.0 (5.4)
145.0 (5.7)
150.0 (5.9)
157.0 (6.2)
165.0 (6.5)
172.7 (6.8)
1500
155.0 (6.1)
163.0 (6.4)
168.0 (6.6)
175.3 (6.9)
180.3 (7.1)
185.4 (7.3)
1800
170.0 (6.7)
178.0 (7.0)
183.0 (7.2)
188.0 (7.4)
193.0 (7.6)
198.1 (7.8)
2100
185.4 (7.3)
190.5 (7.5)
195.6 (7.7)
200.7 (7.9)
205.7 (8.1)
213.4 (8.4)
2400
198.1 (7.8)
200.7 (7.9)
208.3 (8.2)
210.8 (8.3)
218.4 (8.6)
226.1 (8.9)
2700
210.8 (8.3)
210.8 (8.3)
218.4 (8.6)
221.0 (8.7)
231.1 (9.1)
241.3 (9.9)
3000
218.4 (8.6)
218.4 (8.6)
231.1 (9.1)
231.1 (9.1)
251.5 (9.9)
251.5 (9.9)
3600
241.3 (9.5)
241.3 (9.5)
246.4 (9.7)
251.5 (9.9)
259.1 (10.2)
274.3 (10.8)
in = Inch
m m = Millimeter
OSP Design Reference Manual, 4th edition
6-24
© 2007 BICSI®
Chapter 6: Splicing Hardware
Splice Data, continued
Table 6.7, continued
26 AWG two-bank apparatus splice
Main
Cable
Pair
Count
600
mm (in)
600
160.0 (6.3)
900
172.7 (6.8)
195.6 (7.7)
1200
188.0 (7.4)
203.0 (8.0)
213.4 (8.4)
1500
200.7 (7.9)
218.4 (8.6)
223.5 (8.8)
236.8 (9.4)
1800
213.4 (8.4)
233.7 (9.2)
238.8 (9.4)
241.3 (9.5)
261.6 (10.3)
2100
229.0 (9.0)
243.8 (9.6)
251.5 (9.9)
259.1 (10.2)
269.2 (10.6)
2400
241.3 (9.5)
254.0 (10.0)
261.6 (10.3)
271.8 (10.7)
279.4 (11.0)
2700
254.0 (10.0)
269.2 (10.6)
274.3 (10.8)
281.9 (11.1)
292.1 (11.5)
3000
267.0 (10.5)
271.8 (10.7)
279.4 (11.0)
289.6 (11.4)
302.3 (11.9)
3600
284.5 (11.2)
Number of Pair Bridged
900
1200
1500
mm (in)
mm (in)
mm (in)
289.6 (11.4) 297.2 (11.7)
1800
mm (in)
307.3 (12.1) 315.0 (12.4)
in = Inch
m m = Millimeter
NOTES: Zero is straight splice measurement in inline configuration.
For 22 AWG [0.64 mm (0.025 in)] conductors, increase values by 25 percent.
For 24 AWG [0.51 mm (0.020 in)] conductors, increase values by 12 percent.
If sealant boxes are used, increase values approximately 25 percent.
© 2007 BICSI®
6-25
OSP Design Reference Manual, 4th edition
Chapter 6: Splicing Hardware
Testing
Manufacturers offer a variety of plugs and cords to mate with the modules being utilized. With
the use of these modules, testing may be completed during the splicing operation.
Waterproof Splicing
A series of waterproof sealing boxes that encapsulate the splicing module are available.
Optical Fiber Cable
Splice Design
In OSP applications, a designer normally avoids the requirement of optical fiber-to-fiber field
splicing by installing a continuous length of cable. This is normally the most economical and
convenient solution. Splices (see Figure 6.15) cannot always be avoided due to cable plant
layout, length, raceway congestion, requirements for a transition splice between nonlisted OSP
cables and listed cable at the building entrance point, and unplanned requirements (e.g., cable
damaged during the installation or during a cable unearthing).
Figure 6.15
Examples of splices required due to cable routing
12-Strand optical fiber
Field splice
point
12-Strand
optical
fiber
12-Strand
optical fiber
48-Strand
optical
12-Strand optical fiber
fiber
Cable length
in excess of
4 km (2.5 mi)—multimode or
12 km (7.5 mi)—singlemode
Transition
splice
12-Strand
optical fiber
36-Strand optical fiber
Congested duct
allowing only one
cable
Consolidation
field splice point
km = Kilometer
mi = Mile
OSP Design Reference Manual, 4th edition
6-26
© 2007 BICSI®
Chapter 6: Splicing Hardware
Optical Fiber Cable, continued
The physical design of the system should minimize splices whenever possible. In most cases,
the small size and long lengths of optical fiber cable allow the use of separate cable sheaths to
serve each cross-connect, telecommunications room (TR), and intermediate cross-connect
(IC [building distributor (BD)]), providing conduit space allows. This avoids cable splices and
results in fewer different optical fiber-count cables, thus allowing for an easier installation and
typically avoiding minimum order requirement issues. The small incremental cost of additional
sheaths usually offsets the cost of splicing different optical fiber-count cables together.
Splice point locations should be chosen only after considering the requirements for optical fiber
splicing:
•
To effectively perform a splice, the cable ends must reach a satisfactory work surface
(preferably a vehicle or table that is clean and stable). The distance can be as much as
30.5 meters (m [100 feet (ft)]) on each end. The chosen location should have provisions
for storing slack cable after splicing is completed.
•
Physical protection of all slack is recommended, although not required.
•
Splicing and racking slack should be considered when making cable length calculations.
Optical fiber splice closures typically require 2.4 to 3 m (8 to 10 ft) of stripped cable inside
the closure.
In special applications (e.g., the combination of a star and ring topology), access to individual
optical fibers is required without disturbing the remaining optical fibers. The designer should
allow cable slack, normally 9 m (30 ft), allowing for easy mid-span access.
Ideally, the number of optical fibers being accessed will correspond to the number of optical
fibers in the cable units, buffer tube, or unitized subunit (usually 6 or 12 optical fibers). While
this is not required, it provides an easier and cleaner procedure.
A small amount of slack cable (6 to 15 m [20 to 50 ft]) can be useful in the event cable repair
or relocation is needed. If a cable is cut, the slack can be shifted to the damaged point,
necessitating only one splice point in the permanent repair, rather than two splices if an
additional length of cable is added. This results in reduced labor, hardware costs, and link loss
budget savings. Designers should check with the customer for project-specific slack length
and location requirements.
© 2007 BICSI®
6-27
OSP Design Reference Manual, 4th edition
Chapter 6: Splicing Hardware
Optical Fiber Splicing Methods
Two major categories of field-splicing methods for optical fibers are fusion and mechanical.
Both single-fiber and mass-fiber (typically 12 optical fibers) splicing methods are available.
Both are field-proven and have high long-term reliability when completed according to
manufacturer’s instructions.
For OSP splice locations, the splices and stripped cables are typically protected and secured
by a splice closure. For splicing inside a building, a splice enclosure that is secured to a rack,
cabinet, or wall is often used. In both cases, the splice closure or enclosure contains the
optical fiber splices in splice trays or organizers, typically in groups of 6, 12, 24, or more optical
fibers per splice tray or organizer.
Splicing can occur between two optical fiber cables—loose-tube cables containing 250
micrometers (μm) coated optical fiber and tight-buffer cables containing 900 μm buffered
optical fibers. Both mechanical or fusion splice methods can perform 250 μm to 250 μm
splicing, 250 μmm to 900 μm splicing, or 900 μm to 900 μm splicing.
Typically, multimode optical fibers are 50/125 μm or 62.5/125 μm while singlemode optical
fibers are 8 to 9/125 μm. Mechanical or fusion splicing can accommodate both multimode and
singlemode optical fiber.
Single-fiber and ribbon (array) optical fiber (typically 12) splicing methods are available for
both fusion and mechanical methods for various cable constructions.
There are advantages and disadvantages for each method, but the choice primarily depends
on:
•
The information transport systems (ITS) installer’s equipment.
•
Preference.
•
Training.
•
Application.
•
Volume of optical fiber splicing.
All of these methods and categories:
•
Are field-proven.
•
Have excellent long-term reliability.
•
Can be used for termination of optical fiber cables.
OSP Design Reference Manual, 4th edition
6-28
© 2007 BICSI®
Chapter 6: Splicing Hardware
Optical Fiber Splicing Methods, continued
Fusion Splicing
Fusion splicing consists of aligning two clean (stripped of coating), cleaved optical fibers, then
joining and fusing the ends together with an electric arc. Typical splice loss under field
conditions is less than 0.05 decibels (dB) for singlemode optical fiber (maximum allowed is
0.3 dB).
Mechanical Splicing
By comparison, a mechanical splice is an optical junction where two or more optical fiber
strands are aligned and held in place by a self-contained assembly approximately 51 millimeter
(mm [2 inches (in)]) in length. Single-fiber mechanical splices rely upon alignment of the outer
diameter of the optical fibers, making the accuracy of core/cladding concentricity critical to
achieving low splice losses. Mechanical splices can consistently achieve losses on singlemode
optical fibers in the 0.10 to 0.15 dB range (maximum allowed is 0.3 dB).
Mass Splicing
For high optical fiber-count applications, an increasingly popular method is mass splicing. Mass
splicing can be fusion or mechanical. The term mass indicates that multiple optical fibers are
being spliced at once, typically in a ribbon configuration. Most common today are 12-strand
optical fiber ribbons. The chief advantage of mass splicing is speed. Mass splicing is typically
four to five times faster than single-fiber splicing.
Typical loss for this splice is less than 0.10 dB for singlemode optical fiber with a maximum
allowed of 0.3 dB. The system designer needs to understand the loss requirements of the
optical fiber system and the capabilities of the various types of splice equipment (under field
conditions) to manage splicing trade-offs of productivity and splice loss when deciding to use
single-fiber or mass splicing.
Ribbon optical fiber is not necessarily needed to take advantage of mass splicing. Occasionally
there is a requirement to splice loose-tube to ribbon cable. One method of accomplishing this
is to break out the individual optical fibers in the ribbon cable for single-fiber splicing, or
ribbonize the optical fibers from the loose-tube cable.
© 2007 BICSI®
6-29
OSP Design Reference Manual, 4th edition
Chapter 6: Splicing Hardware
Splice Protection
Fusion and mechanical splicing are reliable and suitable for both indoor and outdoor use when
the splices are completed in accordance with the manufacturer’s instructions.
When splicing outdoors, typically the splices and stripped cable should be protected by a splice
closure. When the cable is installed in a splice closure, various methods provide strain relief
and protection of the stripped optical fiber splice. All optical fiber splices are housed in splice
trays or organizers inside a closure. The proper splice tray should be selected based on the
type of protection required by the splice. For example, mechanical splices have a form of
built-in strain relief and optical fiber protection, which are then secured in a splice tray or
organizer. Fusion splices, however, require additional protection and strain relief that can be
provided by heat-shrink sleeves, crimp protectors, or silicone sealant. Heat-shrink and
mechanical crimp connectors are the most common methods.
When splicing inside a building, a splice center can be used when rack or wall space is
available. Additionally, most termination patch panels have built-in or accompanying splice
centers that allow optical fiber termination and through splicing when required.
OSP Design Reference Manual, 4th edition
6-30
© 2007 BICSI®
Chapter 6: Splicing Hardware
Optical Fiber Cable Splicing Hardware Considerations
There are many types of splices and splicing methods that dictate a large variety of splice
trays for a particular hardware unit.
Optical fiber strands and splices must be well organized and protected. The splice tray should
be easy to use and allow for easy reentry.
The minimum bend radius requirements of the optical fiber strands must not be violated. Trays
must be large enough to handle worst-case bending. Trays must provide adequate strain relief
for buffer tubes, pigtails, or pre-terminated modules.
Splice trays are available in metallic or plastic versions, for singlemode or multimode optical
fiber strands, to provide physical protection for both fusion and mechanical splices.
The standard fusion splice tray is a singlemode tray with a 12-strand optical fiber splice
capacity that can be used with loose-tube or tight-buffered cables. A high-precision, molded,
step-slot organizer protects the fusion splice without the need for individual splice protection
parts. The completed splices are placed in the organizer and coated with room temperature
vulcanization (RTV) compound to protect the bare optical fiber strands.
The standard mechanical splice tray is a singlemode tray with a 12-strand optical fiber
capacity. Most splice trays are available with clear, plastic covers for easy visual inspection.
Other trays are available for most other splicing methods.
Splice trays are required to protect and organize optical fiber strands and splices at splice
points (see Figure 6.16). As with the copper closures, additional kits may be required to
complete the closure assembly.
Figure 6.16
Splice tray examples
Singlemode fusion splice tray (12-strand optical fiber splice capacity)
Singlemode mechanical splice tray (12-strand optical fiber splice capacity)
© 2007 BICSI®
6-31
OSP Design Reference Manual, 4th edition
Chapter 6: Splicing Hardware
Hardware Labeling
Proper labeling of hardware is important for system administration. One recommendation is to:
•
Label each panel from left to right, starting at the top and labeling to the bottom.
•
Be consistent with the labeling code.
•
Use the customer’s labeling procedure (campus environment).
•
Identify all splice points on the as-built drawings.
•
Provide written documentation as to:
–
Location.
–
Manufacturer.
–
Type of splice.
–
Pair count or optical fiber strand count.
–
Date of splice.
–
Splice technician’s name.
OSP Design Reference Manual, 4th edition
6-32
© 2007 BICSI®
Chapter 6: Splicing Hardware
References
American National Standards Institute/Telecommunications Industry Association/Electronic
Industries Alliance. ANSI/TIA/EIA-606-A. Administration Standard for Commercial
Telecommunications Infrastructure. Arlington, VA: Telecommunications Industry
Association, 2002.
———. ANSI/TIA/EIA-758. Customer-Owned Outside Plant Telecommunications
Cabling Standard. Arlington, VA: Telecommunications Industry Association, 2004.
Institute of Electrical and Electronics Engineers, Inc.® National Electrical Safety Code.®
Piscataway, NJ: Institute of Electrical and Electronics Engineers, Inc., 2006.
National Fire Protection Association, Inc. NFPA 70. National Electrical Code®, 2005 edition.
Quincy, MA: National Fire Protection Association, Inc., 2005.
© 2007 BICSI®
6-33
OSP Design Reference Manual, 4th edition
Chapter 7
Grounding, Bonding,
and Protection
Chapter 7 discusses the importance, purpose, and
requirements of grounding (earthing), bonding, and electrical
protection for outside plant (OSP). It details the treatment
of exposure to lightning, power contact, power induction,
and ground potential rise (GPR). Respective equipment and
methodologies also are featured.
Chapter 7: Grounding, Bonding, and Protection
Table of Contents
Introduction........................................................................................ 7-1
Exposed Outside Plant (OSP) ......................................................................... 7-1
Exposure to Lightning .............................................................................. 7-2
Power Contact ....................................................................................... 7-3
Power Induction ..................................................................................... 7-3
Ground Potential Rise (GPR) ...................................................................... 7-3
Grounding (Earthing) and Bonding ................................................................... 7-5
Multiground Neutral (MGN) and Non-MGN Power Systems ................................... 7-5
Bonding Telecommunications and Power Grounds .......................................... 7-9
Bonding Requirements ...................................................................... 7-10
Aerial Cable Bonding Requirements ................................................................ 7-10
Maintaining Electrical Continuity of Shields ................................................ 7-10
Metallic Conductors ............................................................................... 7-10
Bonding Support Strands to Ground ......................................................... 7-11
Bonding Cable Shields to Support Strands ................................................. 7-11
Bonding at Power Crossings .................................................................... 7-12
Bonding in Joint Use or Joint Occupancy ................................................... 7-13
Underground/Direct-Buried Cable Dips in Aerial Cable Runs ........................... 7-14
Aerial—Underground Transitions ............................................................... 7-14
Direct-Buried Cable Bonding Requirements ...................................................... 7-14
Direct-Buried Plant Exposed to Power ....................................................... 7-14
Joint Random Direct-Buried Plant ............................................................. 7-16
Methods and Precautions ....................................................................... 7-16
Underground Cable Bonding Requirements ...................................................... 7-16
Metallic Conductors ............................................................................... 7-16
Maintenance Hole (MH) Grounding (Earthing) and Bonding ................................ 7-17
Building Entrance Protection ........................................................................ 7-21
Grounding (Earthing) and Bonding ............................................................ 7-21
Corrosion and Noncorrosion Areas ............................................................ 7-21
© 2007 BICSI®
7-i
OSP Design Reference Manual, 4th edition
Chapter 7: Grounding, Bonding, and Protection
Protectors ........................................................................................ 7-25
Fuseless Protector Housing .......................................................................... 7-25
Fused Protector Housing ............................................................................. 7-25
Fuse Links ................................................................................................ 7-25
Protector Units .......................................................................................... 7-26
Primary and Secondary Protector Units .......................................................... 7-27
Grounding (Earthing) for Lightning Protection ................................... 7-28
Soil Resistance .......................................................................................... 7-28
Ground Resistance ..................................................................................... 7-28
Obtaining a 25-Ohm Ground ......................................................................... 7-29
Bonding Electrodes ..................................................................................... 7-29
Reducing Resistivity ................................................................................... 7-30
Chemical Electrodes .............................................................................. 7-30
Using Ground Enhancement Material ......................................................... 7-30
Advantages of Ground Enhancement Material ............................................ 7-31
Ideal Conditions .................................................................................... 7-31
Concrete-Encased Electrode ........................................................................ 7-31
Building Exterior Grounds ........................................................................ 7-32
Cable to Electrode Connections ............................................................... 7-32
Electrical Protection in Tunnels .......................................................... 7-33
Spacing Between Bonding Points .................................................................. 7-33
Electromagnetic Interference (EMI) .............................................................. 7-34
Mutual Impedance ..................................................................................... 7-34
Recommended Testing Procedures and Criteria ............................................... 7-35
True Root-Mean-Square (rms) Alternating Current (ac) Measurements .......... 7-35
Two-Point Bonding Measurements ............................................................ 7-35
References ....................................................................................... 7-36
OSP Design Reference Manual, 4th edition
7-ii
© 2007 BICSI®
Chapter 7: Grounding, Bonding, and Protection
Figures
Figure 7.1
Ground potential rise ..................................................................... 7-4
Figure 7.2
Multiground neutral power system .................................................... 7-6
Figure 7.3
Non-multiground neutral power system ............................................. 7-7
Figure 7.4
Wye power system ........................................................................ 7-8
Figure 7.5
Delta power system ....................................................................... 7-9
Figure 7.6
Ground connection on a pole (multiground neutral system) ................ 7-12
Figure 7.7
Grounding (earthing) without access to transformers ........................ 7-15
Figure 7.8
Welded bonding attachment to rebar for site-poured
maintenance hole ........................................................................ 7-17
Figure 7.9
Clamped bonding attachment to rebar for precast or
site-poured maintenance hole ....................................................... 7-18
Figure 7.10
Interior grounding (earthing) and bonding for racking ........................ 7-18
Figure 7.11
Underground cable bonding ........................................................... 7-19
Figure 7.12
Maintenance hole bonding ............................................................ 7-20
Figure 7.13
Isolation gap .............................................................................. 7-23
© 2007 BICSI®
7-iii
OSP Design Reference Manual, 4th edition
Chapter 7: Grounding, Bonding, and Protection
OSP Design Reference Manual, 4th edition
7-iv
© 2007 BICSI®
Chapter 7: Grounding, Bonding, and Protection
Introduction
Properly designed and installed electrical grounding (earthing), bonding, and protection can
minimize voltage and currents that may be hazardous to people, property, and
telecommunications equipment. Proper grounding (earthing) and bonding techniques also can
improve the signal integrity of a transmission path or promote the reliable operation of
electronic equipment. The sources of these abnormal voltages and currents are usually
external to the telecommunications cabling. The purpose of electrical protection is to:
• Minimize electrical hazards to system users and protect those engaged in construction,
operation, and maintenance of the system.
•
Reduce the risk of electrical damage to aerial, direct-buried, or underground plant,
telecommunications equipment, and associated buildings or structures.
•
Mitigate transient voltages that can induce unwanted signals on cables.
Where users and plant personnel are concerned, safety from shock hazard is a prime design
consideration.
The National Electrical Safety Code®(NESC®) requires cable shields, support strands, and
other noncurrent-carrying metallic hardware to be effectively grounded. It is especially
important to effectively ground cable shields, support strands, and noncurrent-carrying metallic
hardware at deadends and junction points for noise mitigation, personnel protection, and power
contact protection.
In the United States, the common electrical supply is 120 volt (V) 60 hertz (Hz) nominally. In
many other countries, the common electrical supply is 240 V 50 Hz nominally. In all cases,
refer to local electrical codes and regulations.
Exposed Outside Plant (OSP)
In the United States, the information transport systems (ITS) designer must be familiar with
the definition of exposed OSP cable as defined by the NESC® and the National Electrical
Code ®(NEC ®).
Protective measures are required on aerial, direct-buried, and underground cable when there
is exposure to:
•
Disturbances due to the presence of lightning stroke currents.
•
Voltage induction (e.g., alternating current [ac] power) exceeding 300 V.
•
Accidental contact with power conductors operating at more than 300 V to ground.
•
Ground potential rise (GPR) exceeding 300 V.
The designer should consider all the exposures encountered for a specific cable installation
when determining protection measures. Whatever the source, protective measures should be
coordinated and considered as a whole to abate these exposures.
© 2007 BICSI®
7-1
OSP Design Reference Manual, 4th edition
Chapter 7: Grounding, Bonding, and Protection
Exposed Outside Plant (OSP), continued
The terms exposed and unexposed are used to describe OSP with respect to its vulnerability
to sources of current and voltage. OSP subject to electrical disturbances from any of these
sources is exposed. OSP not subject to these effects is not exposed.
The designer should consider the physical characteristics of the OSP cable (i.e., metallic
components of cable such as a strength member, metallic shield, or conductors) when
determining whether an outside facility should be classified as exposed or unexposed.
Furthermore, the source and severity of the exposure must also be considered to determine
the protection measures to be specified.
Often, a segment of the OSP cabling may not appear to be exposed to lightning and power;
yet, by way of exposed branches or extensions connecting with that segment, it is classified as
exposed. For example, underground plant is not directly exposed to power contact, but
individual cables can be exposed to power or lightning if they extend into an exposed location
by aerial or direct-buried facilities. A telecommunications system is exposed or unexposed
according to whether the OSP serving it is exposed or unexposed.
NOTE:
Consult the appropriate requirements and practices of applicable authorities, regulations, and codes concerning their policies with respect to exposed and unexposed
plant. Frequently, the policy is to treat all locations as exposed and to protect the
plant accordingly.
Exposure to Lightning
IMPORTANT:
Lightning strikes are a common source of hazardous foreign potentials.
OSP cabling is classified as exposed to lightning except when located in:
•
•
•
Areas having five or less thunderstorm days per year and where the
ground resistivity is less than 100 ohm-meters ( Ωm ). Such areas are
rare. For example, in the continental United States, they are found
along the Pacific coast.
Areas where buildings are close and sufficiently high to intercept
lightning.
Campus cabling runs that are 42.7 meters (m [140 feet (ft)]) or less
with the cable bonded to each building ground electrode system.
BICSI recommends that all exterior cable be treated as exposed and
properly protected.
OSP Design Reference Manual, 4th edition
7-2
© 2007 BICSI®
Chapter 7: Grounding, Bonding, and Protection
Exposed Outside Plant (OSP), continued
Power Contact
Since power and telecommunications cabling serve the same customers, OSP facilities for
these services are sometimes located close to one another and may even share the same pole
or trench (i.e., joint-use). Aerial or direct-buried plant that is subject to possible contact by
power conductors operating at more than 300 V to ground is considered to be exposed to
power contacts. All primary power systems operate at a higher voltage than this, while most
secondary systems operate at lower voltages. Such systems must also be considered
hazardous since the currents imposed as a result of accidental contact can severely damage
physical plant or be fatal to personnel.
Power Induction
Disturbances from electromagnetic induction (i.e., power induction) can occur wherever
telecommunications and power lines run parallel for long distances. OSP subject to power
induction of more than 300 V to ground is considered to be exposed. Although lower voltages
may exist as a result of unbalanced power line operation, induced voltages exceeding 300 V to
grounding (earthing) are most likely caused by power line faults.
A properly constructed grounding (earthing) and bonding system will mitigate noise from
power induction sources such as:
•
Electrified railroads.
•
Trolley systems.
•
Subways.
•
Electrified buses.
•
Electrified cranes.
•
Electric substations.
Ground Potential Rise (GPR)
OSP subject to a GPR of more than 300 V to ground is considered to be exposed. The
likelihood of a GPR is greatest in the vicinity of a power generating station or a substation.
Substations are commonly located on campus premises to provide service to the campus and
its associated structures. GPRs can develop between the power station ground and remote
grounds as a result of a fault in the power network and will persist until the fault is cleared.
GPR is a function of the transmission of current to ground at some discrete point. While this
may be temporary (e.g., a cloud-ground lightning strike) or continuous (e.g., operation of a
substation), it creates a difference of potential between different geographical points in the
telecommunications system. Unless the telecommunications system is properly bonded to
ensure electrical continuity and equivalence and grounded to ensure delivery of the charge to
a ground point, the system and persons in contact could be harmed.
© 2007 BICSI®
7-3
OSP Design Reference Manual, 4th edition
Chapter 7: Grounding, Bonding, and Protection
Exposed Outside Plant (OSP), continued
In the following GPR example, the power system multiground neutral (MGN) system ground
receives a 120 V fault (see Figure 7.1). This power fault induces 120 V onto the MGN
ground. The voltage is dissipated through the ground but causes a GPR. Any telecommunications facilities or ground systems located in close proximity to the point of induced voltage will
be influenced by that GPR. In this example, a telecommunications cable shield ground is
located 1.2 m (4 ft) from the induced voltage to the MGN ground. The 120 V fault is
dissipated to a 30 V ground potential rise when it reaches the telecommunications cable shield
ground.
Figure 7.1
Ground potential rise
Telephone
cable shield
ground
Power
conductor
120 V
power
fault
Power system
(MGN) ground
1.2 m (4 ft)
*55 V
0.91 m (3 ft)
*44 V
*36 V
0.6 m (2 ft)
*30 V
0.3 m (1 ft)
*
Voltage to remote earth
ft
m
MGN
V
=
=
=
=
Foot
Meter
Multiground neutral
Volt
Accidental power contacts, power induction, and GPR are individual threats to OSP cabling,
but the protection measures used to prevent one source of power disturbance are generally
effective against all three.
OSP Design Reference Manual, 4th edition
7-4
© 2007 BICSI®
Chapter 7: Grounding, Bonding, and Protection
Grounding (Earthing) and Bonding
Grounding (earthing) refers to the electrical connection of telecommunications hardware to an
effective electrical ground. An effective electrical ground can be the vertical down lead
(VDL) of a power system MGN, a grounded neutral of a secondary power system, or a
specially constructed grounding (earthing) system.
Bonding refers to the electrical interconnection of conductive parts designed to maintain a
common electrical potential. Bonding conductors must be of sufficient gauge to carry
anticipated current due to power contact. Typically, these conductors should be sized so that
no more than 40 V is present along its entire length. If this incalculable, the designer must
consider a short, straight bonding connection.
An effective electrical ground, such as the power MGN, must provide a low impedance path
to earth. Electrical connection to a low-resistance ground permits current to flow to ground
without the build-up of hazardous voltages on the telecommunications cabling, in the event of
power contact.
Electrical connections of aerial plant to anchor rods or down guys are not effective electrical
grounds. These types of connections are high-resistance grounds. A high-resistance ground
does not provide adequate protection against hazardous voltages resulting from power contact
or lightning.
The purpose of grounding (earthing) and bonding in a telecommunications system is to:
•
Reduce the hazard of electrical shock and damage to structures and equipment from
alternating current (ac) and direct current (dc) voltages and from lightning surges.
•
Abate the hazardous and damaging effects of lightning and power surge voltages and
currents in telecommunications facilities.
•
De-energize the power circuit quickly in the event of an accidental contact by causing
operation of power circuit breakers or fuses.
•
Provide paths to ground (earth) for shield currents in metallic cable shields, thereby
reducing the voltages induced in cable conductors.
•
Reduce noise voltages in sensitive circuitry by providing an effective common reference
point for circuit potentials to which outside induced currents can drain without disturbing
circuit operation.
Multiground Neutral (MGN) and Non-MGN Power Systems
MGN and non-MGN power systems vary in structural design from area to area based on
service needs and economy of the design; however, these systems must be compliant with the
NESC ®.
MGN power systems are characterized by a neutral conductor, which originates at the
substation and is carried continuously along the primary and secondary circuits to the
subscriber’s premises. This neutral conductor is grounded at 0.40 kilometers (km [0.25 miles
(mi)]) intervals.
© 2007 BICSI®
7-5
OSP Design Reference Manual, 4th edition
Chapter 7: Grounding, Bonding, and Protection
Multiground Neutral (MGN) and Non-MGN Power Systems, continued
The top wire is the primary circuit and carries high voltage from the power substation to the
secondary circuits. There may be more than one primary conductor on a line, but the neutral
conductor is always below the primary. In an MGN power system, the neutral conductor is
grounded at each transformer and continues through to the secondary circuits and the
customer’s premises (see Figure 7.2).
Figure 7.2
Multiground neutral power system
Primary
Primary
Primary
Primary
Neutral
Neutral
Neutral
Approximately 0.40 km
(0.25 mi) separation
between vertical
down leads
Ground rods placed
at base of pole
km
mi
=
=
Kilometer
Mile
OSP Design Reference Manual, 4th edition
7-6
© 2007 BICSI®
Chapter 7: Grounding, Bonding, and Protection
Multiground Neutral (MGN) and Non-MGN Power Systems, continued
At every transformer pole in an MGN power system, the neutral conductor is connected to a
ground wire that leads down to the ground electrode at the base of the pole. This wire is
called the vertical down lead (VDL). Approximately every 0.40 km (0.25 mi), even where no
transformers are located, the power company runs a VDL from the ground rod to bond the
primary neutral and secondary neutral for an effective ground.
The multi-grounding (earthing) of this power system is more common than non-MGN systems
(see Figure 7.3) because over-current devices (e.g., fuses or relay-protection systems)
operate more rapidly due to low impedance ground paths.
NOTE:
The MGN system discussed above is the type of MGN system generally used in the
United States and may vary from area to area.
In cases where aerial runs are installed on a joint-use pole with a non-MGN system, a
dedicated telecommunications VDL shall be provided at least every 0.40 km (0.25 mi).
The ITS designer should coordinate the use of an MGN as the grounding (earthing) source
with the power company when placing cables on a joint-use pole line. In these instances,
bonding the cable support strand to the MGN should ground both the cable shield and the
cable support strand. This assumes that the cable shield has already been bonded to the cable
support strand. Grounding (earthing) is accomplished by connecting a bonding conductor from
the support strand to the VDL.
Coordinate grounding (earthing) and bonding connections to the VDL or MGN with the power
company. Many power companies require that only their qualified employees make these
connections.
In cases where the telecommunications pole line intersects at a joint-use pole supporting
power lines, ground the cable support strand by bonding it to the MGN. Midspan crossings of
telecommunications cables and power lines should be avoided if possible. If unavoidable,
buried crossings should be considered. Most power companies will not allow midspan
crossings without an attachment.
Figure 7.3
Non-multiground neutral power system
Three primaries
Primary
bushings
Lightning
arrester
Three secondaries
© 2007 BICSI®
7-7
OSP Design Reference Manual, 4th edition
Chapter 7: Grounding, Bonding, and Protection
Multiground Neutral (MGN) and Non-MGN Power Systems, continued
Non-MGN power systems do not utilize a MGN conductor. The two most common non-MGN
are the:
•
Grounded wye power system—This system has a neutral ground at a single point in the
power line. Figure 7.4 illustrates a wye power system.
NOTE:
There may not be a neutral conductor carried with the phase conductors.
Figure 7.4
Wye power system
208 V
A
B
120 V
120 V
208 V
Neutral
208 V
C
Ground
120 V
V = Volt
OSP Design Reference Manual, 4th edition
7-8
© 2007 BICSI®
Chapter 7: Grounding, Bonding, and Protection
Multiground Neutral (MGN) and Non-MGN Power Systems, continued
•
Three-phase, ungrounded delta power system—A delta power system is a -legged,
ungrounded configuration with an equal potential between each phase of the transformer.
Figure 7.5 illustrates a Delta power system.
Figure 7.5
Delta power system
A
B
240 V
240 V
C
240 V
V = Volt
Non-MGN power systems also vary in structure and appearance. A non-MGN power system
may not have a continuous neutral conductor or pole grounding (earthing) system.
In a typical non-MGN system, there are two primary feeds; each one is attached to a primary
bushing on the transformer. The transformer’s secondary tap is grounded to the VDL. There
is no ground connection from the primary of the transformer to the secondary.
NOTE:
The power company can provide information on the type(s) of power system(s)
used in their area.
Bonding Telecommunications and Power Grounds
A bond between power and telecommunications plant must be established using at least a
6 AWG [4.1 millimeters (mm [0.16 inches (in)])] bonding conductor.
© 2007 BICSI®
7-9
OSP Design Reference Manual, 4th edition
Chapter 7: Grounding, Bonding, and Protection
Bonding Requirements
Aerial Cable Bonding Requirements
Maintaining Electrical Continuity of Shields
It is important that electrical continuity of aerial cable shields be maintained. Bond all
connecting direct-buried or underground cable shields to provide:
•
An effective reference for lightning and power currents.
•
Radio frequency interference (RFI) mitigation.
•
Electromagnetic interference (EMI) mitigation.
Metallic Conductors
The required intervals for bonding the telecommunications support strand to the power system
MGN depend on the power voltages involved.
NOTE:
The grounding (earthing) and bonding requirements should be reviewed with the
power and access provider (AP) if it is a jointly used pole line.
All connectors and clamps must be listed, rated for outside use, and properly sized to accept
the wire and strand size.
The bonding of telecommunications hardware to power company facilities on aerial plant shall
be performed:
•
Only by ITS personnel on telecommunications cable plant.
•
In or below the telecommunications pole space.
•
Only when authorized by the power company.
ITS personnel shall not perform any work within nor climb into the power space on a pole.
Where the connection to the MGN must be made above the telecommunications space,
sufficient wire should be coiled and temporarily attached to the pole for later connection by
power company personnel.
NOTE:
The telecommunications bonding conductor should only be connected to the power
utility MGN by the power utility. This requires the submittal of the information to the
power utility on a preapproved or other negotiated form or document.
OSP Design Reference Manual, 4th edition
7-10
© 2007 BICSI®
Chapter 7: Grounding, Bonding, and Protection
Aerial Cable Bonding Requirements, continued
Bonding Support Strands to Ground
Suspension strands are bonded to reduce the possibility of electrical shock and to minimize
plant damage.
Grounding (earthing) and bonding of the suspension strand will:
•
Limit the voltage on the strand in the event of an accidental contact with energized power
conductors.
•
De-energize the power circuit quickly in the event of an accidental contact by causing
operation of power circuit breakers or fuses.
•
Minimize induced voltages that may be on the strand.
•
Establish and maintain shield continuity of the cable, terminals, and splices.
•
Bond the strands of separate cables or wires together:
–
Every 0.40 km (0.25 mi).
–
At each crossover.
–
At each branch.
Bonding Cable Shields to Support Strands
Cable shields should be bonded to support strands at frequent intervals to prevent arcing and
to provide a low impedance ground for power contact or lightning-related surge currents.
Shielded cables should be bonded between the shield and support strand at all splices,
terminals, and load points. The method used to bond the shield to the support strand depends
on the types of enclosures.
If a shielded cable is exposed to lightning, the shield should be bonded to the strand every
0.40 km (0.25 mi), usually at splices and terminals.
An example of grounding (earthing) and bonding the telecommunications support strand is
shown in Figure 7.6.
© 2007 BICSI®
7-11
OSP Design Reference Manual, 4th edition
Chapter 7: Grounding, Bonding, and Protection
Aerial Cable Bonding Requirements, continued
Figure 7.6
Ground connection on a pole (multiground neutral system)
Coil and tie bonding
conductor to pole
for attachment by
power company
6 AWG [4.1 mm (0.16 in)]
bonding conductor doubled
under strand bond clamp
Staple
Support
strand
6 AWG [4.1 mm (0.16 in)]
bonding conductor doubled
under strand bond clamp
Staples
AWG
in
mm
=
=
=
American Wire Gauge
Inch
Millimeter
Bonding at Power Crossings
Where possible, aerial telecommunications cable and electrical distribution lines should be
crossed on jointly used or occupied poles rather than midspan. At joint pole crossings with
MGN-type power lines, the cable support strand should be connected to the MGN via a VDL.
Span crossings may be used where it is not feasible to have:
•
Joint pole crossings with electrical distribution lines.
•
Aerial crossings with electrical transmission lines.
OSP Design Reference Manual, 4th edition
7-12
© 2007 BICSI®
Chapter 7: Grounding, Bonding, and Protection
Aerial Cable Bonding Requirements, continued
Bonding in Joint Use or Joint Occupancy
Where the same poles used for MGN electrical supply circuits support a telecommunications
cable, the cable shield and support strand should be bonded to the MGN. These bonding
connections should be made:
•
Where the joint use or joint occupancy arrangement begins and ends.
•
On every electrical supply pole that carries a VDL to which the following are connected:
•
–
Transformers
–
Capacitors
–
Other types of power equipment that draws load current under normal conditions
If the joint use or joint occupancy section is longer than 0.8 km (0.5 mi), these bonds
should be made to the MGN every 0.40 km (0.25 mi). The NESC requires additional
grounding (earthing) considerations for certain support strand sizes where the support
strands are exposed to possible power contacts, power induction, or lightning. If the
ampacity of the support strands is not adequate for system grounding (earthing)
conductors, additional bonds must be made at intervals of 0.20 km (0.12 mi).
Where the same poles used for non-MGN electrical supply circuits support a telecommunications cable, shields should be grounded by bonding them to a telecommunications ground
system.
Under certain conditions, it may be necessary to use an additional telecommunications
grounding (earthing) system with ground rods connected to the support strand and cable
sheath.
VDL on utility poles interconnected to transformers or capacitor banks should be designed by
power company engineers for direct bonding to the power system neutral. At such locations,
visual inspections from the ground should be made before climbing the pole to determine
whether the VDL is actually connected to the neutral.
WARNING:
© 2007 BICSI®
If the VDL is not connected to the neutral, the power company should
be informed and the wire regarded as energized. Telecommunications line
workers should not touch or climb the pole until the power company
reconnects the VDL to the neutral.
7-13
OSP Design Reference Manual, 4th edition
Chapter 7: Grounding, Bonding, and Protection
Aerial Cable Bonding Requirements, continued
Where bonding of the support strand and MGN is recommended, the bond should be
accomplished by the appropriate method for the conditions prevailing at the pole as listed
below:
•
If the pole already has a VDL connected to the MGN, then a bonding conductor should be
installed by power company personnel.
•
A bonding conductor should be left with sufficient slack to connect it to the MGN.
Connection of the bonding conductor to the MGN should be made only by the power
company. For recommended intermediate bonds, a pole already equipped with a VDL
should be selected and a bonding conductor installed.
In most instances, bonding the cable shield to the MGN will reduce noise levels in the
telecommunications cable.
Underground/Direct-Buried Cable Dips in Aerial Cable Runs
No special protection is required at junctions of aerial cable and short underground or directburied plastic-sheathed cable dips in aerial cable runs.
Aerial—Underground Transitions
If an aerial cable exposed to lightning is connected to a single underground cable that extends
for 305 m (1000 ft) or more before paralleling other cables, ground the aerial cable shield at
the last pole. The shield and supporting strand should be bonded to an MGN vertical down
lead (VDL) if one exists. Otherwise, use a telecommunications ground rod.
Direct-Buried Cable Bonding Requirements
Direct-Buried Plant Exposed to Power
In general, bond wherever cable is specified. The following methods should be used to protect
telecommunications cable direct-buried near power conductors. Protection requirements are
based on the distances between the two systems:
•
Less than 0.91 m (3 ft) separation—To maintain shield continuity in terminals and splice
closures, direct-buried telecommunications cable must be bonded when it is located less
than 0.91 m (3 ft) from a power cable. Bonding must be performed regardless of whether
the cables are in the same or separate trenches. Additionally:
–
Telecommunications cable shields should be bonded to the power neutral or to the
power apparatus at all above-ground telecommunications terminals, pedestals, apparatus cases, and direct-buried cable closures located within 1.83 m (6 ft) of any aboveground power apparatus.
–
For every terminal located near a power transformer, provide a bonding conductor for
connection to either the transformer housing, primary neutral, secondary neutral, or
secondary pedestal served from the transformer. This connection must be installed by
power company personnel.
OSP Design Reference Manual, 4th edition
7-14
© 2007 BICSI®
Chapter 7: Grounding, Bonding, and Protection
Direct-Buried Cable Bonding Requirements, continued
–
Grounding (earthing) should be performed at every other pedestal if no transformer is
present (see Figure 7.7).
–
The ground shall not be omitted on any two adjacent terminals.
–
The distance between ground locations shall not exceed 305 m (1000 ft).
–
No exposed point of the telecommunications cable should be more than 152 m (500 ft)
from a bond connection.
Figure 7.7
Grounding (earthing) without access to transformers
Pedestals
Bond cable
to ground rod
Bond cable
to ground rod
Earth
B
B
B
B
B
Direct-buried
cable
Place ground rods
(Length varies with soil conditions
—not to exceed 305 m [1000 ft])
ft
m
•
=
=
Foot
Meter
More than 0.91 m (3 ft) separation—When direct-buried telecommunications cable and
power cable are separated by more than 0.91 m (3 ft), only bonding is required.
Where direct-buried telecommunications cable is separated from direct-buried power cable
with more than 0.91 m (3 ft) of well-tamped earth, the chance for accidental contact with
power conductors is minimal.
© 2007 BICSI®
7-15
OSP Design Reference Manual, 4th edition
Chapter 7: Grounding, Bonding, and Protection
Direct-Buried Cable Bonding Requirements, continued
Joint Random Direct-Buried Plant
Joint random direct-buried plant is plant direct-buried in the same trench as power conductors
where a minimum 305 mm (12 in) separation has not been maintained. Joint random spacing is
limited to distribution cable that is joint buried. The NESC specifies the voltage limitations in
joint random construction (see NESC, Section 35, Rule 354).
In addition to voltage limitations placed on joint random construction, the NESC specifies that
the power conductors include a bare or semi-conducting, jacketed, grounded conductor in
continuous contact with the earth. An overall insulating jacket with a copper concentric
conductor that is grounded a minimum of eight times per 1.6 km (1 mi) in each random directburied section is required.
Close coordination with the local power company is required.
Methods and Precautions
Bonds must be made using minimum 6 AWG [4.1 mm (0.16 in)] solid copper wire and listed
clamps. Convenient bonding locations should be chosen to minimize the length of the bonding
wire.
Maintain cable shield bond continuity of all telecommunications plants.
Underground Cable Bonding Requirements
Metallic Conductors
Telecommunications and power facilities occupy separate structures in an underground plant;
therefore, underground metallic conductor cables are not exposed to power contact.
Bonding cables in telecommunications maintenance holes (MHs) reduces the overall
resistance to ground and equalizes the potentials between the cables. Equalizing the potentials
between cables protects personnel by reducing the possibility of shock hazards and minimizes
plant damage.
Cables used in the underground conduit system have either an outer metallic sheath or a
plastic sheath. Generally, cables with an outer metallic sheath are bonded at each MH, while
cables with an outer plastic sheath are bonded at MHs where a splice is made.
In some instances, when cables are exposed because of aerial to underground OSP
(e.g., cable dip) extensions, the following guidelines should be applied:
•
Establish and maintain continuity of all metallic cable elements.
•
Nonmetallic splice case bonding connections, as well as lead sleeves and metallic splice
cases, should be connected to the MH grounding (earthing) system at every MH.
•
Plastic sheath cables do not need to be bonded at pull-through MHs.
OSP Design Reference Manual, 4th edition
7-16
© 2007 BICSI®
Chapter 7: Grounding, Bonding, and Protection
Maintenance Hole (MH) Grounding (Earthing) and Bonding
To bond and ground monolithic (site-poured) MHs, follow the same procedures used in
precast MHs. If these procedures are not followed, a driven ground rod and associated
bonding ribbon is required (see Figures 7.8 through 7.10).
Figure 7.8
Welded bonding attachment to rebar for site-poured maintenance hole
Welded
Grade 60
new billet
steel rebar
Bonding
ribbon
Concrete
Bonding
ribbon
connector
© 2007 BICSI®
7-17
OSP Design Reference Manual, 4th edition
Chapter 7: Grounding, Bonding, and Protection
Maintenance Hole (MH) Grounding (Earthing) and Bonding, continued
Figure 7.9
Clamped bonding attachment to rebar for precast or site-poured maintenance hole
(In concrete)
Brass ground clamp
Bonding ribbon
Rebar
To wall inserts
Figure 7.10
Interior grounding (earthing) and bonding for racking
Copper
ground wire
1.8 m (6 ft)
Concrete
inserts
Sump
Ground rod
ft
m
=
=
Foot
Meter
OSP Design Reference Manual, 4th edition
7-18
© 2007 BICSI®
Chapter 7: Grounding, Bonding, and Protection
Maintenance Hole (MH) Grounding (Earthing) and Bonding, continued
Concrete in earth tends to draw moisture from the soil and maintain its own water content.
This condition accounts for its consistent low resistivity even under desert conditions. Ground
identification plates must be used either in precast or site-poured MHs.
Figure 7.11 illustrates how splice closures within a MH are bonded and grounded.
Figure 7.11
Underground cable bonding
Telecommunications
cable
Maintenance hole
bonding ribbon
Splice closures
Maintenance hole
ground system
Cable
racks
When a splice occurs in an MH, the metallic strength member and other metallic sheath
components of the cables must be bonded to the MH grounding (earthing) system. All
closures should also be bonded to the MH ground. No bonding is required in handholes (HHs)
and MHs when the cable is pulled through without a splice.
© 2007 BICSI®
7-19
OSP Design Reference Manual, 4th edition
Chapter 7: Grounding, Bonding, and Protection
Maintenance Hole Grounding (Earthing) and bonding, continued
Figure 7.12 shows the bonding of metallic members within the MH.
Figure 7.12
Maintenance hole bonding
Side view of 2-piece precast maintenance hole
Cable
rack
Bonding
ribbon
Seam between
top and bottom
section of
maintenance hole
Sump
Ground rod
NOTE:
Bonding ribbon is clamped or welded to embedded steel at the time of casting. Bond
connection for splice cases, cables, etc., is established with use of vertical bonding
ribbon. At time of cable rack installation, attach bonding ribbon.
OSP Design Reference Manual, 4th edition
7-20
© 2007 BICSI®
Chapter 7: Grounding, Bonding, and Protection
Building Entrance Protection
All exposed telecommunications cables that contain metallic components (e.g., metallic shield,
metallic strength member, or metallic pair) require some form of electrical protection at the
building entrance, including:
•
Grounding (earthing) and bonding of cable metallic sheath components and metallic
strength
members.
•
Installation of protectors to metallic pairs, along with fuse links, where required.
•
Air pressure pipe that is exposed and is metallic or contains a metallic vapor barrier also
requires grounding (earthing) and bonding. At locations where air pressure equipment is
connected to the air feeder pipe, connect the metallic lining of the pipe to the MH
grounding (earthing) system.
Grounding (Earthing) and Bonding
The telecommunications main grounding (earthing) busbar (TMGB) is the location within a
building where all grounding (earthing) conductors are connected to the earth electrode (see
ANSI-J-STD-607-A, Commercial Building Grounding (earthing) [Earthing] and
Bonding Requirements for Telecommunications). Grounding (earthing) and bonding is
performed to maintain equalization of voltages between:
•
Equipment ground conductors.
•
Grounding (earthing) electrodes.
•
Metallic cable sheath components.
•
Cable metallic strength members.
•
Main cross-connect ground.
The metallic sheath components and metallic strength members of all cables entering the
building must be connected to the TMGB.
When buildings are served by exposed cables:
•
Ground entrance cable shields as close to the entrance as possible.
•
Use fire-resistant splice cases for all splices of entrance cables.
•
Ground the protector or protected cable terminal using a minimum 6 AWG [4.1 mm
(0.16 in)] copper ground wire, to the TMGB.
•
Protector ground, power ground, and interior metallic water pipe system must be bonded
together.
Corrosion and Noncorrosion Areas
When there are no insulating joints, use 6 AWG [4.1 mm (0.16 in)] copper wire or bonding
ribbon to bond entrance cable metallic sheath components and strength members to the
TMGB.
© 2007 BICSI®
7-21
OSP Design Reference Manual, 4th edition
Chapter 7: Grounding, Bonding, and Protection
Building Entrance Protection, continued
Insulating joints (isolation gaps) may be required in certain areas where cable corrosion is a
problem such as in the vicinity of dc trolley and rail systems or pipeline cathodic protection
systems. These joints do not provide protection against hazardous voltages.
WARNING:
Cathodic protection systems are used to provide a constant low current
connection to various metallic ducts or other metallic structures in order to
mitigate galvanic corrosion of the structures. Although the cathodic
protection system may provide the appearance of a ground connection, it
may not be used as part of the building’s grounding (earthing) electrode
system. The designer must not attach the telecommunications grounding
(earthing) and bonding system to such a cathodic protection system.
In a noncorrosion (low-risk) area, the sheaths or shields of all OSP cables must be bonded
with 6 AWG [4.1 mm (0.16 in)] copper wire or bonding ribbon to the telecommunications
grounding (earthing) system.
In a corrosion (high-risk) area:
•
Install insulating joints or isolation gaps on all cables entering a building. The purpose of
these kind of joints is to separate the building ground from the OSP ground, and to prevent
the flow of currents that may cause electrolytic corrosion.
OSP Design Reference Manual, 4th edition
7-22
© 2007 BICSI®
Chapter 7: Grounding, Bonding, and Protection
Building Entrance Protection, continued
For cables that are exposed to lightning inductive interference or power contact, use isolation
gaps as follows:
•
Bond the OSP sides of shields or sheaths, and isolate them from the telecommunications
grounding (earthing) system. Figure 7.13 shows the configuration of an isolation joint.
Figure 7.13
Isolation gap
Isolation gap
Isolation joint
© 2007 BICSI®
7-23
OSP Design Reference Manual, 4th edition
Chapter 7: Grounding, Bonding, and Protection
Building Entrance Protection, continued
When insulating joints are used:
•
Bridge insulating joints on exposed cables with decoupling capacitors to minimize coupled
noise.
•
Use 6 AWG [4.1 mm (0.16 in)] copper wire or bonding ribbon on the outside of the
insulating joint to bond the metallic sheath components and strength members of all
entering cables (paired conductor and optical fiber). Cables and all associated metal
(i.e., elements) must be isolated from all grounded objects (e.g., building steel, equipment,
racks) on the OSP side of the insulating joint.
•
Locate insulating joints as near as possible to the point of entry.
•
On the building side of the insulating joint, use a minimum of 6 AWG [4.1 mm (0.16 in)]
copper wire or bonding ribbon to bond the metallic sheath components and strength
members of all cables to the TMGB.
OSP Design Reference Manual, 4th edition
7-24
© 2007 BICSI®
Chapter 7: Grounding, Bonding, and Protection
Protectors
There are two general types of protector housings—fused and fuseless. All fuseless protector
housings are equipped with voltage-limiting devices (e.g., carbon blocks, gas tubes, or solidstate components).
Fuseless Protector Housing
Fuseless protectors do not offer protection for sustained fault current like fused protectors.
When used in conjunction with fuseless protectors where power exposure exists, a fuse link is
required between exposed plant and the protector in order to minimize any fire or shock
hazard in the event of a sustained power contact.
Fused Protector Housing
Fuse links may not protect a connecting cable from lightning exposure because the operating
(time-current) characteristics of fuse links of any type could allow lightning surges to pass
through the fuse without operating it.
Fused protectors are required when:
•
•
No fuse link has been provided, as in the following examples:
–
Direct-buried drop wire is connected to 19 AWG [0.91 mm (0.036 in)] or 22 AWG
[0.64 mm (0.025)] conductors of joint direct-buried plant, and the protector is located
on an exterior wall or within the building being served.
–
Drop wire is run more than one span on joint-use poles with power and is not shielded
by a grounded strand or grounded conductor.
A portion of a service wire is jointly trenched with power distribution cables greater than
300 V to ground.
Fuseless protectors should only be installed with a fusible link.
NOTE:
Fusible links are current-limiting devices. Fuseless protectors (e.g., carbon, gas tube,
or solid state) are voltage-limiting devices.
Fuse Links
Fuse links are shorter sections of finer (larger AWG number) gauge cable than normally
required for transmission purposes. In the event of prolonged current flows caused by foreign
potentials (e.g., power contacts), fuse links burn open, protecting terminating equipment or
cabling.
The protector stubs, or internal protector wiring, should be at least two gauges finer than the
entrance cable. For transmission reasons, fuse links should be as short as possible. However,
a minimum of 0.6 m (2 ft) of fuse link is required.
© 2007 BICSI®
7-25
OSP Design Reference Manual, 4th edition
Chapter 7: Grounding, Bonding, and Protection
Protector Units
Protector units limit the voltage difference between conductors and ground by providing a low
impedance path to ground when the operating voltage of the protector unit is reached.
Protector units are required on all exposed circuits entering the building; this includes tip and
ring conductors contained in conventional paired conductor cables and those in hybrid cables.
The following list outlines some of the more common devices used to prevent damage to
equipment and personnel for exposed OSP facilities:
•
Air gap discharge protectors—Features a carbon air gap and fail-safe mechanism that
shorts to ground when a voltage exceeds its rating.
•
Gas tube protectors—Generally contains a two or three electrode high amperage ceramic
nonradioactive gas-tube arrestor and a fail-safe mechanism. These are used in areas
where frequent transient overvoltages are a problem or where operating values must be
tightly controlled. This type of protector will recover repeatedly from the overvoltage and
provide 30 to 40 times longer life than carbon air-gap protectors.
•
Solid state protectors—Contains diodes intended for use with sensitive equipment. They
can be equipped with heat coils of varying values. The diode is a fast semiconductor
switch with operating voltages nearly independent of transient rise time. It can operate
repeatedly and provides longer protection life than either carbon air gap or gas-tube
protectors.
•
Current-interrupting devices (fusing)—Overcurrent protective units with a circuit-opening
fusible element that is severed when heated by the passage of an overcurrent. They are
normally one-time devices.
•
Isolating transformers—These units have no direct electrical connection between the
primary and secondary sides.
OSP Design Reference Manual, 4th edition
7-26
© 2007 BICSI®
Chapter 7: Grounding, Bonding, and Protection
Primary and Secondary Protector Units
The designer should consider providing both primary overvoltage protection and secondary
overcurrent protection for exposed OSP twisted-pair copper cables. The NEC® requires
primary protection for cables considered exposed to lightning, power line crosses, or
accidental power contact. Secondary protection should also be considered to protect
equipment from “sneak currents” typically defined as continuous foreign current exceeding
0.35 amperes. Typically, sneak currents are not high enough to engage primary protectors but
can cause damage to equipment and can present a fire hazard if the current is sustained.
Fast response secondary protectors conforming to Underwriters Laboratories Inc.® (UL®)
497A, Secondary Protectors for Communications Circuits, should be installed in series
between the primary protectors and the switching equipment at the main building and between
the primary protectors and the station equipment at the remote buildings. These protection
devices can consist of overcurrent limiting heat coils or sneak current fuses.
NOTE:
Per the NEC®, secondary protectors on exposed circuits are not intended for use
without primary protectors. Overcurrent conditions are caused by a low impedance
connection to ground, power line contact (either direct or indirect), or via a line short
circuit.
It is permissible (and preferred) to utilize an assembly that integrates both primary and
secondary overvoltage and overcurrent protection rather than create two protector fields. For
example, a single protection assembly that uses modules having both current and fast response
voltage suppression capability, and that meet safety requirements for primary and secondary
protection, would protect both personnel and equipment.
It is recommended that protector modules be equipped with in-service test points so that faulty
or blown modules can be determined without accidentally disengaging a working circuit when
determining whether the fuse module has operated or not.
© 2007 BICSI®
7-27
OSP Design Reference Manual, 4th edition
Chapter 7: Grounding, Bonding, and Protection
Grounding (Earthing) for Lightning Protection
Soil Resistance
The goal of any grounding (earthing) system is to provide a low-impedance path for fault
currents until they reach the earth. When considering the grounding (earthing) conditions at
any site, it is essential to test soil resistivity. In general, black dirt, or soils with high organic
content, is usually a very good conductor because they tend to retain more moisture, leading to
low resistivity. Sandy soils, which drain faster, tend to be less moist and are higher in
resistivity. Solid rock and volcanic ash have virtually no moisture and have such high resistivity
as to be practically useless as a grounding (earthing) material.
Ground Resistance
Ground resistance is usually measured with an instrument called an earth ground resistance
tester. This meter consists of:
•
A voltage source.
•
Switches that change the instrument’s measurement range.
Grounding (earthing) system installers may be required to measure or otherwise determine the
ground resistance of the system they have installed. The NEC, section 250.56, requires a
single electrode consisting of a rod, pipe, or plate that does not have a resistance to ground of
25 ohm ( Ω )or less to be augmented by one additional electrode of the types listed in section
250.52(A) 2 through 7. Multiple electrodes should always be installed so that they are at least
1.8 m (6 ft) apart. Spacing electrodes at distances greater than 1.8 m (6 ft) increases rod
efficiency, meaning that the earth ground resistance for ground rod configuration may be
lowered in value. Therefore, proper spacing and quantity of the electrodes ensures the
maximum amount of fault current that can be safely discharged into the earth.
To properly design a grounding (earthing) system, the earth resistivity should be measured.
Several measurement methods can be used however the most effective of these is a fourpoint test method, known as the Wenner Method. This method is to specifically determine the
soil resistivity of a given location and depth. Once soil resistivity (which is measured in either
ohms-per-meter [ Ω /m] or ohms-per-centimeter [ Ω /cm]) is determined, it is cross-reference
with a graph that will help the designer gauge the resistance of a ground rod configuration
before it is even installed.
When the ground rods are installed, they should be measured for their effectiveness. This
measurement is known as a three-point, fall-of-potential method and is performed so that the
installer can accurately measure the resistance of any ground rod configuration with respect
to the surrounding soil. This measurement is often made before any grounding (earthing) or
bonding conductor terminations are made to the ground rods.
NOTE:
Instructions for setting up and making these measurements are included with the
testing equipment.
OSP Design Reference Manual, 4th edition
7-28
© 2007 BICSI®
Chapter 7: Grounding, Bonding, and Protection
Obtaining a 25-Ohm Ground
Per the NEC, section 250.52, the ground rod shall be a minimum of 2.5 m (8 ft) in length.
A ground at every location with a resistance-to-ground of 25 ohm or less cannot always be
accomplished with a 2.5 m (8 ft) ground rod. Instead, it may be necessary to use a longer rod,
place and connect multiple rods, or use other grounding (earthing) methods for earth
preparation. This is especially true in areas with extremely high resistivity.
NOTE:
Lower or equal to 25 ohm ground is a safety requirement and has nothing to do with
system performance. Some system performance requirements can only be met by
less than one impedance to ground. The National Security Agency (NSA) specifies
0.000025 ohm impedance to ground. For additional information, visit their Web site
at www.nsa.gov.
Bonding Electrodes
Types of electrodes include:
•
Solid copper.
•
Copper-clad steel.
•
Plain steel.
•
Galvanized steel.
•
Stainless-clad steel.
•
Solid stainless steel.
When selecting the type of electrode to use, the designer should consider:
•
The soil chemistry.
•
Any nearby electrically bonded structures.
•
Whether the electrode is installed in a corrosive area.
Soil with a high sulfur content may cause copper to corrode.
Any direct-buried steel items connected to a copper grounding (earthing) system will corrode
due to the galvanic action between the copper and the steel. The rate of galvanic corrosion
depends on the ratio of exposed copper and steel areas. The higher the ratio of copper
exposed to steel, the greater the rate of corrosion. Coating steel to protect it can make
corrosion worse since there will probably be at least one unprotected area. With only a small
steel area exposed, the copper to steel ratio is high and all the corrosion takes place at the
small area of unprotected steel and at a much higher rate than if the steel were uncoated.
Steel ground rods are often used to prevent the galvanic corrosion possible with copper rods.
To protect the steel, the rods are usually galvanized (zinc coated). The zinc creates a galvanic
cell with any nearby, bonded steel, with the zinc being the anode and thus sacrificing itself to
protect the steel.
© 2007 BICSI®
7-29
OSP Design Reference Manual, 4th edition
Chapter 7: Grounding, Bonding, and Protection
Bonding Electrodes, continued
NOTE:
In most circumstances, earthing and grounding (earthing) are synonymous in their
definition and use. The term earthing is more popular in the United Kingdom and
Europe, while grounding (earthing) is most commonly used in North America. In
some areas of the world, grounding (earthing) definitions tend to be more broadly
interpreted and applied.
Any dc equipment operating in the area can cause severe corrosion on the grounding
(earthing) system. An example of this may be a dc transit system substation. The large
amounts of stray dc currents possible can cause severe corrosion of any nearby steel that
may be part of the return circuit and grounding (earthing) system. Some transit systems use a
stainless steel grounding (earthing) system in their substations.
Reducing Resistivity
In the absence of low-resistance soil conditions, there are other options for improving
conductivity. These include filling the ground rod hole with bentonite, treating the soil with a
salt (copper magnesium sulfate or rock salt), or using ground enhancement material.
Chemical Electrodes
Some installations specify a very low resistance, often lower than what is easily obtainable
using multiple rods, deep driven rods, or long direct-buried grounding (earthing) conductors. In
these instances, it may be necessary to select a “chemical-type electrode.”
Chemical-type electrodes are copper tubes containing a salt that slowly leaches into the soil,
lowering the soil’s resistance and possibly contaminating the soil; however, non-contaminating
materials, generally referred to as ground enhancement materials, are available. Bentonite, a
form of clay, is a common ground enhancement material. To use bentonite, a hole is drilled into
the earth. The ground rod or conductor is then placed into the hole and the bentonite added,
usually in dry form.
Bentonite will absorb up to five times its weight in water and increase up to 13 times its dry
volume, obtaining moisture from the surrounding soil. This creates exceptional contact
between the rod or conductor and the soil. Bentonite’s ideal moisture content is three times its
weight in water, at which time its resistivity will be approximately 2540 ohm-mm (100 ohm-in).
Although bentonites’s resistivity is much higher than that of the grounding (earthing) rod, it is
much lower than that of the surrounding soil. Therefore, in effect, bentonite increases the
effective diameter of the rod.
Using Ground Enhancement Material
Other ground enhancement materials are available commercially, some with a resistivity of
less than 119 ohm-mm (4.7 ohm-in [less than five percent of the resistivity of bentonite]). This
material can be used dry or, when premixed with water, hardens like concrete. Ground
enhancement materials are permanent and will not leach any chemicals into the soil. They can
be used to surround a rod or conductor in a drilled hole, or may be used to surround a
conductor in a trench.
OSP Design Reference Manual, 4th edition
7-30
© 2007 BICSI®
Chapter 7: Grounding, Bonding, and Protection
Reducing Resistivity, continued
Ground enhancement material improves grounding (earthing) effectiveness regardless of soil
conditions and is ideal for areas with high resistance (e.g., rocky ground, mountain tops, sandy
soil). Ground enhancement material can be installed wet or dry.
Advantages of Ground Enhancement Material
Ground enhancement material has many advantages over bentonite and rock salt. Unlike rock
salt, it does not require periodic charging treatments or replacement. And, because it is
chemically stable and very low in sulfate and chloride, it protects ground conductors from
corrosion instead of attacking them like salts do. Once set, it maintains high conductivity in
wet or dry conditions. Ground enhancement material meets environmental requirements for
landfill.
Ground enhancement material may be used where ground rods cannot be driven, or where
limited land area makes adequate grounding (earthing) difficult with conventional methods.
Although it costs more initially than standard fill materials such as bentonite, only a small
amount is needed, so the size of the grounding (earthing) array can be reduced dramatically.
Ideal Conditions
Even under ideal circumstances, soil structure can vary and make it difficult to achieve
uniform, low levels of resistivity across a wide area. However, with ground enhancement
material, the results can be a lot more predictable because it offers:
•
Reduction in earth resistance that remains for the life of the system even during dry
seasons.
•
Wet or dry installation.
•
Test-proven resistivity of 119 ohm-mm (4.7 ohm-in) or less.
•
Maintenance-free grounding (earthing).
In summary, ground enhancement materials improve grounding (earthing) system performance.
Concrete-Encased Electrode
This type of ground uses a non-insulated conductor (no smaller in diameter than 4 AWG
[5.2 mm (0.20 in)] encased along the bottom of a concrete building foundation footing in direct
contact with the earth. The length of the conductor’s run inside the concrete is important, as
the effective resistance is inversely proportional to the length of conductor within the
concrete.
Typically, a 6 m (20 ft) run—3 m (10 ft) in each direction—gives a five ground in 1000 ohm-m
(3280 ohm-ft) soil conditions.
© 2007 BICSI®
7-31
OSP Design Reference Manual, 4th edition
Chapter 7: Grounding, Bonding, and Protection
Concrete-Encased Electrode, continued
Building Exterior Grounds
When effectively grounded, columns around the perimeter of a building are excellent
grounding (earthing) electrodes and provide a good path to the earth for any fault currents that
may be imposed on the system. When grounding (earthing) large or multiple-building facilities,
perimeter grounding (earthing) provides an equipotential ground for all the building and
equipment bonded to the perimeter ground. The grounding (earthing) conductor size depends
on the size of the electrical service.
Cable to Electrode Connections
According to the NEC, section 250.8, “Grounding (earthing) conductors and bonding jumpers
shall be connected by exothermic welding, listed pressure connectors, listed clamps, or other
listed means. Connection devices or fittings that depend solely on solder shall not be used.
Sheet metal screws shall not be used to connect grounding (earthing) conductors or
connection devices to enclosures.”
Exothermic welding is the most permanent method of making cable-to-ground rod or smallsized cable-to-cable connections. An exothermic system is the most convenient process for
achieving welded ground connections. The resulting molecular bond produces a permanent
connection that will not loosen or corrode over the lifetime of the installation.
The exothermic system makes fast, positive grounds without any outside power source or
heat. Connections are made by powdered metals (copper oxide and aluminum) within a mold
by using a flint lighter to ignite the powdered metal. Once the connection is made, the ceramic
mold can be left intact or broken off, revealing a permanent connection made in less than five
minutes.
OSP Design Reference Manual, 4th edition
7-32
© 2007 BICSI®
Chapter 7: Grounding, Bonding, and Protection
Electrical Protection in Tunnels
Protecting metallic telecommunications cabling plant and personnel from hazardous electrical
effects is particularly important in joint-use utility tunnels. Electrical protection requirements of
other utilities may be similar in many ways, but the overall susceptibility of telecommunications
facilities to induced voltages and EMI influence the requirements. Acceptable electrical
protection for telecommunications installments should:
• Maintain adequate separation between metallic telecommunications cable and electrical
power facilities to prevent accidental contact between the telecommunications and
electrical plant.
•
Yield a facility where there is no possibility of accidental contact with energized electrical
power facilities.
•
Maintain separation and/or shielding between metallic telecommunications and electrical
plant to ensure that voltages hazardous to either workers or plant are not induced into the
telecommunications facilities.
•
Ground and bond the telecommunications facilities to the electrical facilities to prevent a
hazardous potential difference from developing between various surfaces that workers
may contact during normal work operations.
Protective conduit is generally not used for telecommunications cabling. Using conduit reduces
access required for inspection, maintenance, and random location of splices. Because flame
spreads easily in a tunnel, polyvinyl chloride (PVC) conduit should never be used. Power
cables can dissipate heat more effectively when exposed to air than when enclosed in conduit.
Evaluate each situation based on its particular characteristics. Where possible, telecommunications and electrical facilities should be placed on opposite sides of the tunnel. In some cases,
this placement eliminates the need for additional shielding of the power or telecommunications
cables and reduces the effects of EMI.
Spacing Between Bonding Points
When determining the spacing between bonding points in a tunnel there is no general, practical
rule. Many factors must be considered. For example, cables placed in a tunnel will not be
subjected to the lightning hazard of aerial plant. Therefore, less frequent bonding points are
required than in aerial plant. In some cases (e.g., when entering utility facilities that may carry
lightning currents), bonding at the access and equipment areas may be adequate. Provide a
common grounded bonding conductor throughout the tunnel.
© 2007 BICSI®
7-33
OSP Design Reference Manual, 4th edition
Chapter 7: Grounding, Bonding, and Protection
Electromagnetic Interference (EMI)
Three major components of electromagnetic-induced interference problems that relate to
metallic telecommunications transmission facilities placed in a joint-use utility tunnel with an ac
or dc power system, are the:
•
Unbalanced electromagnetic fields of the power system.
•
Coupling between the power and telecommunications systems.
•
Susceptibility of the telecommunications system.
The magnitude of the power line influence is determined by the magnitude of the:
•
Unbalanced current being transmitted.
•
Physical configuration of the line.
If large enough, voltages induced into a telecommunications plant can create personnel safety
hazards and service problems. The harmonics of 60 Hz (particularly the odd triples such as
540 Hz and 900 Hz) produce circuit noise and can interfere with normal equipment operation.
This is especially true of electronic equipment designed to operate at low signal levels.
Methods of minimizing the power system influence include using well balanced, three-phase
systems and filters to reduce the harmonics.
Mutual Impedance
The coupling or mutual impedance between power and metallic telecommunications facilities
is a function of the:
•
Physical separation between them.
•
Length (in meters/feet) of exposure.
•
Resistance of the return path for the unbalanced current.
•
Power and telecommunications line shielding effectiveness.
In a tunnel, using shielding on either facility (where appropriate) can reduce coupling.
The separation requirement overshadows other utilities’ requirements; therefore, metallic
telecommunications cables should be placed at maximum separation from power cables.
Two characteristics of the telecommunications circuit that determine susceptibility or extent to
which the circuit is adversely affected by inductive fields are the:
•
Amount of shielding provided by the telecommunications cable sheath or by other
grounded conductors.
•
Balance of the telecommunications circuit.
OSP Design Reference Manual, 4th edition
7-34
© 2007 BICSI®
Chapter 7: Grounding, Bonding, and Protection
Recommended Testing Procedures and Criteria
Most qualified electrical installers do not test the grounding (earthing) and bonding system for
a building prior to its connection to the telecommunications grounding (earthing) and bonding
infrastructure. However, performing certain tests to evaluate the bonding connection between
the telecommunications busbars and the ac grounding (earthing) electrode system is
recommended. This testing should be performed after the cabling and grounding (earthing)
infrastructure are installed but prior to either the final approval of the cabling plant or end-use
equipment installation.
True Root-Mean-Square (rms) Alternating Current (ac)
Measurements
Measuring the ac current on the bonding conductor for telecommunications cables or bonding
conductors reveals the unwanted presence of any ac current flow. A reading of zero amperes
(A) is the best possible reading for any bonding conductor. However, some sites have bonding
conductors that exhibit some value greater than zero A due to induction of ac and dc currents
on cable sheaths.
As a guide, the recommended maximum ac current value on any bonding conductor should
be less than one A. The recommended maximum dc current value should be less than
500 milliamperes (mA). The acceptable ac and dc current levels may change depending on
the equipment needs.
If abnormally high ac current levels are present on any bonding conductor, a dangerous
condition likely exists within the area of testing. Therefore, one must be accustomed to
wearing the proper safety gear and taking precautions when splicing cables or grounding
(earthing) cable sheathes.
Two-Point Bonding Measurements
A two-point bonding measurement is performed using an earth grounding (earthing) resistance
tester that is configured for a continuity test. An earth ground tester generates a test ac
current that is manufacturer-specific and less susceptible to the influences of dc current. As a
result, it is more accurate than the standard volt-ohm-milliammeter (VOM).
The test is performed by connecting the meter leads between the nearest available grounding
(earthing) electrode (e.g., ground rod) and other metallic items within the area where the
grounding (earthing) or bonding connections exist. The recommended maximum value for the
bonding resistance between these two points is 0.1 ohm (100 milliohms [m ohm]). In central
office facilities, the acceptable resistance between any two points may be less than
100 m ohm, possibly 50 m ohm.
NOTE:
© 2007 BICSI®
Before performing this test, the equipment manufacturer should be consulted for
detailed instrument setup and safety precautions.
7-35
OSP Design Reference Manual, 4th edition
Chapter 7: Grounding, Bonding, and Protection
References
American National Standards Institute. ANSI J-STD-607-A. Commercial Building
Grounding (Earthing) and Bonding Requirements for Telecommunications. Arlington, VA:
Telecommunications Industry Association, 2002.
National Fire Protection Association, Inc. NFPA 70. National Electrical Code®, 2005 edition.
Quincy, MA: National Fire Protection Association, Inc., 2005.
National Security Agency. www.nsa.gov.
Institute of Electrical and Electronics Engineers, Inc.® National Electrical Safety Code®.
Piscataway, NJ: Institute of Electrical and Electronics Engineers, Inc., 2006.
Underwriters Laboratories Inc.® UL 497A. Secondary Protectors for Communications
Circuits. Northbrook, IL: Underwriters Laboratories, Inc., 2001.
OSP Design Reference Manual, 4th edition
7-36
© 2007 BICSI®
Chapter 8
Right-of-Way
Chapter 8 features the types of right-of-way (R/W) and
related easements and permits. It also describes accurate
and legally acceptable methods of describing property,
restrictions, covenants, conditions, liens, and encumbrances
necessary for outside plant (OSP) design implementation.
Chapter 8: Right-of-Way
Table of Contents
Right-of-Way ...................................................................................... 8-1
Introduction ................................................................................................ 8-1
Definition .................................................................................................... 8-2
Types of Right-of-Way (R/W) ........................................................................ 8-3
Purchasing Right-of-Way (R/W) ...................................................................... 8-3
Options ...................................................................................................... 8-4
Acquiring Easement or Right-of-Way (R/W) ...................................................... 8-4
Public Right-of-Way (R/W) ............................................................................ 8-5
Types of Right-of-Way (R/W) Facilities ............................................................ 8-5
Other Considerations .................................................................................... 8-5
Easements .................................................................................................. 8-6
Right-of-Way (R/W) Easements and Permits ..................................................... 8-6
Property Descriptions ......................................................................... 8-9
Methods of Describing Property ........................................................ 8-10
Introduction .............................................................................................. 8-10
Rectangular Grid System ............................................................................. 8-10
Mercator Projection System ......................................................................... 8-17
State Coordinate System ............................................................................ 8-18
Metes and Bounds ..................................................................................... 8-19
Subdivision Plat and Description ................................................................... 8-23
Centerline Description ................................................................................. 8-24
Point Description ........................................................................................ 8-25
Reference Description ................................................................................. 8-26
Summary of Property Descriptions ................................................................ 8-26
Real Estate Law ............................................................................... 8-27
Fee Ownership .......................................................................................... 8-27
Leasehold ................................................................................................. 8-28
Easement ................................................................................................. 8-28
License .................................................................................................... 8-28
Life Estate ................................................................................................ 8-28
Ownership ................................................................................................ 8-29
Single Ownership .................................................................................. 8-29
Joint Ownership .................................................................................... 8-29
Title Transfer ............................................................................................ 8-30
© 2007 BICSI®
8-i
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Escrow ................................................................................................ 8-30
Conveyance ......................................................................................... 8-30
Grant or Warranty Deed ......................................................................... 8-31
Quitclaim Deed ..................................................................................... 8-31
Bargain and Sale Deed ........................................................................... 8-31
Patent ................................................................................................ 8-31
Mortage and Deeds of Trust ................................................................... 8-32
Contact of Sale .................................................................................... 8-32
Adverse Possession .................................................................................... 8-32
Eminent Domain (Condemnation) .................................................................. 8-33
Chain of Title ..................................................................................... 8-34
Restrictions, Covenants, and Conditions ........................................... 8-35
Liens and Encumbrances ................................................................... 8-36
Appraisers ................................................................................................ 8-36
Engineering .......................................................................................... 8-37
Legal .................................................................................................. 8-37
Appraisal ............................................................................................. 8-37
Negotiation .......................................................................................... 8-39
Private Right-of-Way (R/W) ......................................................................... 8-40
Obtaining and Recording a Private Easement .................................................. 8-41
Contents of the Private Easement Document ................................... 8-42
Easement Document ................................................................................... 8-42
Permit Information ........................................................................... 8-43
State Highway Permit ................................................................................. 8-43
Application ........................................................................................... 8-43
Approval Process .................................................................................. 8-46
Enforcing the Permit .............................................................................. 8-46
Railroad Right-of-Way (R/W) ........................................................................ 8-46
Railroad Permit .......................................................................................... 8-46
Application ........................................................................................... 8-47
Permit Approval and Starting Work ........................................................... 8-47
Upon Completion of Work ........................................................................ 8-47
Retention of Records ............................................................................. 8-47
Sale of Physical Plant ............................................................................ 8-47
Special Requirements for Direct-Buried or Underground Plant ........................ 8-47
Sample Letter of Request for Railroad Permit .................................................. 8-50
Underground Casings under Railroads ............................................................ 8-51
OSP Design Reference Manual, 4th edition
8-ii
© 2007 BICSI®
Chapter 8: Right-of-Way
Figures
Figure 8.1
Method of township numbering ........................................................ 8-11
Figure 8.2
Theoretical township numbering ....................................................... 8-12
Figure 8.3
Section subdivision ........................................................................ 8-14
Figure 8.4
Small subdivision ........................................................................... 8-15
Figure 8.5
Legal subdivision and lotting ............................................................ 8-16
Figure 8.6
State coordinate system ................................................................ 8-18
Figure 8.7
Use of the protractor ..................................................................... 8-19
Figure 8.8
Naming conventions for metes and bounds ........................................ 8-21
Figure 8.9
Metes and bounds ......................................................................... 8-22
Figure 8.10 Subdivision plat and description ....................................................... 8-23
Figure 8.11 Centerline description ..................................................................... 8-24
Figure 8.12 Point description ........................................................................... 8-25
Figure 8.13 Associated construction drawing for state permit application ................ 8-45
Figure 8.14 Casing lengths for various railroad crossing angles .............................. 8-48
Figure 8.15 Layout of a railroad crossing ........................................................... 8-49
Figure 8.16 Arrangements for different casing sizes ............................................. 8-52
Tables
Table 8.1
Specifications for steel casing ......................................................... 8-54
Example
Example 8.1 Typical state permit application ....................................................... 8-44
© 2007 BICSI®
8-iii
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
OSP Design Reference Manual, 4th edition
8-iv
© 2007 BICSI®
Chapter 8: Right-of-Way
Right-of-Way (R/W)
Introduction
The concept of right-of-way (R/W) or the use of land for the public good is rooted in antiquity.
The royal road built in 4500 B.C. by the king of Assyria, consisted of a 23.8 meter (m [78 foot
(ft)]) R/W stretching from the Persian Gulf to the Mediterranean Sea (2,857 kilometers [km
(1775 miles [mi])]). This R/W was considered so important that the king declared that any
person found to have encroached on the R/W would be impaled in front of the palace. Today,
encroachment would more appropriately be handled in a civil court.
Although the contents of this section are written as BICSI best practices, the outside plant
(OSP) designer must understand R/W laws of the countries that practice OSP design and
installation. The OSP designer is advised to seek out R/W professionals to ensure compliance
in the geographic area of the OSP design work.
Designers who deal with OSP construction will be involved in acquisition of R/W. Even if not
directly involved in the actual R/W acquisition, designers need to be aware of the responsibilities that other parties have in obtaining R/W, including:
•
Acquisition processes.
•
Types of R/W required.
•
Legal ramifications involving clients.
Although clients can require that the contractor be responsible for obtaining the R/W
documents, the clients must execute the documents because they own the physical plant to be
installed.
The R/W acquisition process can be one of the greatest factors that affects a project’s
schedule. When choosing various construction alternatives, the designer should consider the
potential difficulty in R/W acquisition. As an OSP project becomes more invasive, the R/W
acquisition process becomes more difficult and time consuming. For example, installing optical
fiber cable in an incumbent local exchange carrier’s (ILEC’s) existing underground duct
system has little adverse impact on a community and is likely to be supported by public
officials. Conversely, trenching a roadway in an urban center to install new duct for optical
fiber cable is likely to cause traffic delays and other associated impacts, creating a more
difficult acquisition process.
Projects with more adverse impacts are likely to take more time because the R/W granting
authority will want a higher level of detail and may seek additional information for assurance
that impacts have been mitigated to the greatest extent possible. Depending on the locality, the
R/W granting authority may also negotiate an exaction (e.g., fee) for compensation due to
impacts they feel are particularly burdensome.
It is crucial to ensure that all R/W issues have been properly identified. If one small segment
of an OSP route is not properly authorized, that segment becomes the weakest link and
prevents the entire OSP project from proceeding.
© 2007 BICSI®
8-1
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Introduction, continued
One issue involving R/W is the terms under which the rights are acquired. The need for
access to maintain the facilities that are placed to rebuild, reinforce, and expand or remove
must be met. The more difficult or undefined the terms are, the more likely access will be
denied. The designer must consider these issues before executing the R/W documents.
Definition
R/W is the legal right to pass through or over property owned by another party. This includes
the land on which facilities are built. These facilities can take the form of:
•
Transmission lines.
•
High-pressure gas lines.
•
Railroads.
•
Telecommunications facilities.
R/W can be a:
•
Fixed width (e.g., roads, railroads, utilities).
•
Variable width (e.g., expensive land, permanent structures).
In previous chapters, OSP has been considered as the facilities connecting buildings on
contiguous property. However, in certain instances there could be a requirement to bridge the
gap between several pieces of property that make up the complex being served. In that
instance, it is necessary to acquire the permissions of other landowners to cross the adjacent
property. The legal document used to acquire this permission can be an easement, license, or
permit. Permits are normally used when the R/W crosses public property (e.g., a roadway) or
some private land (e.g., a railroad).
Usually, OSP facilities are placed on the customer’s property. When placing a facility on the
customer’s property, only the customer’s permission is required unless unusual situations exist
(e.g., the presence of wetlands or railroad spurs into the property).
If a customer plans to continue facilities beyond the property’s boundaries, permission is
required from others, including the:
•
Government (e.g., city, county, state, federal).
•
Department of Transportation (DoT).
•
Railroads.
•
Utilities.
•
Private property owners.
NOTE:
All agencies have different requirements and restrictions for placing facilities.
Government authorities with legal jurisdiction are often referred to as authorities
having jurisdiction (AHJs).
OSP Design Reference Manual, 4th edition
8-2
© 2007 BICSI®
Chapter 8: Right-of-Way
Definition, continued
Acquiring access to public R/W is more difficult for customers who are not franchised utility
providers. Public R/W is typically reserved for franchised utility providers such as:
•
Power.
•
Water.
•
Sewer.
•
Telephone.
•
Cable television.
•
Gas.
Even franchised utility providers can be required to pay substantial annual premiums for the
right to use the public R/W. These premiums can be based on the linear footage of the
easement and facilities.
EXAMPLE:
If multiple cables are placed in one trench, the premium could be based on
the total cable footage of all cables placed in the trench as opposed to the
length of the trench itself.
Types of Right-of-Way (R/W)
There are two primary categories of R/W, but a third category shares characteristics of the
other two.
•
Public R/W involves land owned by government agencies.
•
Private R/W involves land owned by an individual, company, or corporation.
•
Railroad R/W involves land owned by railroad companies. Though privately owned,
railroad companies are granted much greater power over land use and procurement than
other private landowners and in that respect resemble public R/W.
Purchasing Right-of-Way (R/W)
Purchasing private R/W grants the purchaser the same rights as any property owner, as well
as the responsibility to pay all related taxes and fees associated with ownership. Generally,
R/W is purchased when placing structures such as:
© 2007 BICSI®
•
Buildings.
•
Towers.
•
Remote property locations.
8-3
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Options
If it has been determined that the facilities need to extend beyond the boundaries of a
customer’s property, a decision must be made whether to use public R/W or private R/W.
If the decision is to use public R/W, the only option is to acquire a permit or license through a
permitting process since the purchasing of public R/W is typically not possible.
If the decision is to use private R/W, two options become available:
•
Purchasing a strip of land from the property owner.
•
Negotiating an easement from the property owner for the placement and maintenance of
the facilities.
Acquiring Easement or Right-of-Way (R/W)
The decision to purchase a private R/W or to acquire an easement should not be taken lightly.
Depending on the complexity of an R/W issue, it could be beneficial to employ a company
specializing in R/W acquisition.
Much like the information transport systems (ITS) industry, an entire industry is built around
the discipline of R/W and easement acquisition. The professionals employed in this business
possess various certifications confirming their credibility just as the designations of BICSI’s
Registered Communications Distribution Designer® (RCDD®); Outside Plant (OSP)
Specialist; Network Transport Systems (NTS) Specialist, Wireless Design (WD) Specialist,
Installer, Level 1; Installer, Level 2; or Technician attest to the expertise of individuals in the
ITS industry.
One such example of an industry recognized association that trains and certifies professionals
employed in the business of R/Ws is the International Right-of-Way Association (IRWA
[United States and Canada]). Membership in IRWA with appropriate credentialing ensures a
minimum level of qualification for individuals representing as R/W agents. For example, the
designation of Senior Right-of-Way Agent indicates the individual:
•
Is a member of the IRWA.
•
Has attended the requisite IRWA training courses.
•
Has more than five years of R/W experience.
•
Has training in:
–
Appraisals.
–
Engineering.
–
Environmental.
–
Negotiation/acquisition.
–
Property management.
–
Relocation assistance.
–
Surveying.
–
Titles.
OSP Design Reference Manual, 4th edition
8-4
© 2007 BICSI®
Chapter 8: Right-of-Way
Public Right-of-Way (R/W)
Public R/W permits generally are used for placing utilities on the areas immediately adjacent
to roads, highways, byways, and bridges. Acquiring a public R/W permit usually requires
obtaining permission from the appropriate government agencies through a process known as
easement acquisition. Examples of government agencies with jurisdiction over the R/W could
be:
•
Municipal (city).
•
County.
•
Regional.
•
State.
•
Federal.
The actual process and regulations are different for each government agency. Designers must
be familiar with the procedures required by the agency involved. Failure to do so could
hamper the ability to protect the best interests of clients. The agencies usually have preprinted forms that are used to apply for the permit.
The permit details a specifically defined route along, under, over, or across the governmentowned property within which OSP facilities could be placed. The permit also contains the
rules and regulations by which the permit is granted.
NOTE:
Before including specifications for obtaining a permit in a request for quote (RFQ),
consult with the appropriate government agencies.
Types of Right-of-Way (R/W) Facilities
The type of R/W is directly related to the type of facility planned for the project, as follows:
•
Direct-buried
•
Underground
•
Aerial
•
Wireless
•
Combination of the above
Other Considerations
Utilities placed in public R/W occasionally cross private lands. Sometimes, it is easier and less
expensive to obtain private R/Ws than to attempt to acquire a permit on a public domain.
It is also possible to obtain a permit to cross waterways and wetlands. If the waterway is
navigable, contact the AHJ (e.g., United States Army Corps of Engineers, U.S. Coast Guard).
If the area is designated a wetland, avoid it if at all possible. If it is unavoidable, consider
directional boring as an alternate. Coordinate all activities and permits through the appropriate
AHJ.
© 2007 BICSI®
8-5
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Easements
Whether public or private, the granting of an easement is the approval to use a specified strip
of land in the case of placing a telecommunications facility for a specified purpose. Typically,
easements are obtained for the placement of:
•
Underground utilities.
•
Overhead utilities.
•
Wireless utilities.
An easement also gives the holder the right:
•
Of ingress/egress (entering/exiting).
•
To place and maintain the facilities being proposed.
A landowner who grants an easement is precluded from building a structure of any kind on the
easement but retains the right to use the land within certain limits to:
•
Plant grass.
•
Farm.
•
Otherwise use the property.
Since land is considered one of the most valuable possessions a person could acquire, its
ownership and transfer is subject to significant regulation. Therefore, it is necessary to have a
basic understanding of the methods used to describe and identify land.
Right-of-Way (R/W) Easements and Permits
An easement from the individual property owner is required before any excavation on private
property begins. However, the party responsible for the work must be clearly stipulated in a
contract before excavation begins.
When pursuing easements, it is important to remember that the building owner, building user,
and property owner are often different parties.
Most local municipalities require construction permits to be obtained before any excavation
begins. Other locations (e.g., government property, railroad crossings, airports, bridges,
navigable waterways, wetlands) also require special permits and/or environmental impact
studies. These are high-cost items. Submittal of these items does not guarantee route
approval. Some processes take years and end with disapproval.
To better prepare for permit approval, a meeting with the permit granting authority should be
scheduled to obtain information about the permit granting process. At this meeting, the
following questions are useful:
•
What permits will be required to perform this work? Be prepared to provide a preliminary
overview of your project to obtain feedback. If permits are required, ask for application
forms and any written regulations, ordinances, bylaws, or typical specifications associated
with the permit. This information is critical in the design phase of a project.
OSP Design Reference Manual, 4th edition
8-6
© 2007 BICSI®
Chapter 8: Right-of-Way
Right-of-Way (R/W) Easements and Permits, continued
•
Are there any plans to pave or do utility work along our proposed route? This information
is important to know to coordinate your work with other proposed work. This could cause
your project to be delayed or could provide an argument to request an accelerated
permitting process.
•
Are there any portions of our route that are in another agency’s jurisdiction? Roadways
could be under the jurisdiction of a municipal, county, state, regional agency, or a
combination of these governmental entities. It is not always obvious where the boundaries
of these jurisdictional boundaries begin and end. The people responsible for maintenance
of the roadways are typically well aware of jurisdictional boundaries.
NOTES: Accurate drawings generally are required with all permit applications. Many
authorities require scaled computer-aided design (CAD) drawings.
Some local governmental bodies (i.e., municipalities and counties) require a fee,
based on distance, to obtain a permit. These fees may be based on a per foot
cost for buried facilities and include other administrative and policing
assessments that may be required for the particular area being permitted.
Where such permits are needed, require bidding contractors to include these
costs in their estimation. These permits also may require that final changes in
the form of as-built drawings be submitted to the AHJ.
© 2007 BICSI®
•
Is there a government agency that has a geographical information system (GIS) or CAD
plans for our route? Obtain this data in an electronic format and use it as a base map for
your construction and permitting plans. With more government agencies developing GIS
databases, obtaining base map data is becoming increasingly easy. Obtaining base map
data in a digital format can save an enormous amount of time and money.
•
Do you have as-built plans showing existing utilities? If excavation is proposed, identifying
exiting utilities near your route on a plan will be necessary. To ensure that your proposed
route minimizes the potential to cause damage to existing utilities during construction or
maintenance, the permit granting authority will review this plan.
•
What are your bonding and insurance requirements? A contractor is almost always
required to post a bond and insurance prior to construction in a public R/W. Knowing
these requirements will help you qualify contractors.
•
How often does the permit granting authority meet and what is their permitting process?
This information is important to help in the development of a schedule for your project. It
is also important to know if there is any period of the year when the permitting granting
authority does not meet. Many government boards and commissions limit meetings during
the summer and holidays to accommodate volunteer member’s vacation schedules.
•
What are the winter moratorium rules? In geographically northern locations, it is common
to limit or prohibit underground work in the winter. This is due to problems with
compaction of subsurface materials during freezing conditions and to avoid the safety
hazard of plow trucks hitting steel plates left over trenches. Waivers of winter moratoriums are often granted for emergency situations.
8-7
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Right-of-Way (R/W) Easements and Permits, continued
•
Are there any utilities that are not members of a one-call location system (see Chapter 5:
Pathways and Spaces)? Not all utilities are members of these organizations. To prevent
potentially expensive utility hits or face worse consequences, including serious injury or
death, it is critical to ensure that all existing utilities are notified so that their plant can be
properly marked in the field prior to any subsurface work.
•
Do you restrict work on newly paved streets? If trenching is proposed down a roadway,
you need to know if there are restrictions or prohibitions on working in newly paved
streets. This could affect the route selection and an aerial option may be required.
•
Are there any sensitive issues or areas of special concern that should be known? Is the
work going to require special considerations to ensure access is maintained throughout the
construction process (e.g., in front of a school, fire station, hospital)?
Business cards should be exchanged. Contact information is always necessary. Most
government officials will expect the OSP designer to ensure that the project moves through
the permitting process. It is important to ensure that all of the permit granting authority’s
issues and concerns have been addressed.
NOTE:
Take the initiative to ask if you are scheduled to meet with any boards or commissions. Do not assume you will be notified and guided through the permitting process.
OSP Design Reference Manual, 4th edition
8-8
© 2007 BICSI®
Chapter 8: Right-of-Way
Property Descriptions
In the case of R/W acquisition, the property description is essential for the
identification of existing land ownership. Once the proposed route has been identified, the
property descriptions are used to identify the precise boundary lines of the R/W.
This property description is required to:
•
Describe the tract or parcel in precise detail so that any interested party may identify it.
•
Meet the legal requirements to pass title.
The property description is normally composed of five distinct segments:
•
Intent—The description of the property must be such that the buyer, seller, and any other
interested party not familiar with the property can read and understand the intent of both
the seller and buyer.
•
Location—Each parcel of land has a unique location on the earth. The description must be
in sufficient detail that its precise location can be fixed in relation to its surroundings. This
can be accomplished by reference to a fixed survey monument, an established road
centerline, or a larger survey of which this property is a part.
•
Geometric shape—A continuous series of bearings and lines that totally encompass the
property (i.e., metes and bounds).
•
Size—The area within the geometric shape should be described to an acceptable degree
of accuracy.
•
Ownership—The description of the property shall state the name of the current owner.
Additional items include references to the:
•
Public land record.
•
Name of the surveyor who completed the land survey upon which the record is based.
In the case of an easement, the conveyance document should clearly define the rights being
acquired along with the specific use. For aerial plant, minimum line heights should be
specified.
© 2007 BICSI®
8-9
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Methods of Describing Property
Introduction
Accurate land measuring and describing requires a standardized measurement system. Many
countries have converted to the metric system, but their original units of measurement
remained. Documents such as deeds and R/Ws, in many cases have not been converted.
Therefore, the designer should have an understanding of both the old and current land
measurement systems. For example, when working in the states of Texas and California,
knowledge of the Spanish/Portuguese measurement system is required. The Texan vara is
84.6 centimeters (cm [33-1/3 inches (in)]), while the Californian vara equals 83.8 cm (33 in).
Accurate and legally acceptable methods of describing property in use in the United States
and Canada are the:
•
Rectangular grid system.
•
Coordinate system (State Coordinate System in the United States and Dominion Land
Survey [DLS] system in Canada).
•
Mercator projection system
•
Metes and bounds description.
•
Subdivision plat and description.
•
Centerline description.
•
Point description.
•
Reference description.
Following are brief descriptions of each of these methods.
Rectangular Grid System
The U.S. rectangular grid system, established by the Continental Congress in 1785, is in use in
all states west of Ohio with the exception of a portion of the state of Texas. As part of the
system, 35 special meridians, called principal meridians, running in a north-south direction,
were established. Along with the principal meridians, base lines running in an east-west
direction provided the base of reference for rectangular land division.
The first principal meridian is the west boundary line of the state of Ohio. The corresponding
baseline is the 41st parallel. From this point, the rectangular grid system consists of a series of
guide meridians spaced at 39 km (24 mi) intervals. The guide meridians run parallel to the
principal meridian and are called First Guide Meridian East, Second Guide Meridian East, or
First Guide Meridian West, and so forth. Corresponding to the guide meridians are the
standard parallels north and south.
The first principal meridian in Canada was set out in 1870 by Col. Dennis, near Pembina, west
of Winnipeg at longitude ( λ ) of 97 degrees (°) 27 minutes (’) 28.4 seconds (“) W (i.e., the
Chicago connection), with the First Base Line being the 49th Parallel.
OSP Design Reference Manual, 4th edition
8-10
© 2007 BICSI®
Chapter 8: Right-of-Way
Rectangular Grid System, continued
These are labeled as First Standard Parallel North, Second Standard Parallel North, or First
Standard Parallel South, and so forth. The 39 km (24 mi) squares formed by these lines are
known as quadrangles and are displayed in Figure 8.1.
Figure 8.1
Method of township numbering
North and south from baseline and east and west from meridian
Range line
T.3.N.
Township line
Meridian
T.2.N.
R.3.W.
R.2.W.
T.1.N.
Baseline
R.1.W.
R.1.E.
R.2.E.
R.3.E.
Range line
T.1.S.
T.2.S.
Township line
T.3.S.
Each quadrangle is further subdivided into 16 townships that are 9.7 km (6 mi) on a side.
Townships are arranged in four tiers above and four tiers below the baseline and are
numbered according to their position above and below the baseline. For example, the first
township above the baseline would be referred to as Township 1 North (T.1.N.).
© 2007 BICSI®
8-11
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Rectangular Grid System, continued
The quadrangles are arranged in four columns east and four columns west of the guide
meridian. These columns are called ranges and are referred to as Range 1 East (R.1.E.),
Range 1 West (R.1.W.), and so forth.
Townships are further divided into 36 sections, each being 1.6 km (1 mi) on a side, as shown
in Figure 8.2.
Figure 8.2
Theoretical township numbering
36
31
32
80 ch
33
34
35
36
6 mi—480 ch
31
80 ch
1 mi
80 ch
6
5
4
3
2
1
6
12
7
8
9
10
11
12
7
18
17
16
15
14
13
18
19
20
21
22
23
24
19
25
30
29
28
27
26
25
30
36
31
32
33
34
35
36
31
1
6
5
4
3
2
1
6
13
24
6 mi—480 ch
1
ch = Chain
mi = Mile
OSP Design Reference Manual, 4th edition
8-12
© 2007 BICSI®
Chapter 8: Right-of-Way
Rectangular Grid System, continued
Before further subdividing the sections within the township, one must understand the units of
measurement that define the section. Referring to Figure 8.2, each township is shown as being
9.7 km (6 mi)—480 chains on a side. The primary units of linear measurement are:
•
1 mi equals 1609 m (5280 ft).
•
1 mi equals 80 chains.
•
1 chain equals 100 links.
•
1 link equals 20 centimeters (7.87 in).
•
1 rod, pole, or perch equals 5 m (16.5 ft).
NOTE:
The linear measurement generally used in R/W description is rod.
Units of area are:
•
1 acre equals 10 square chains.
•
1 acre equals 4046.86 square meters (m2 [43,560 square feet (ft2)]).
•
1 square mile equals 259 hectares (ha [640 acres]).
Based on these measurements, a theoretical township is 15.5 km2 (6 mi2), containing
36 sections, each being one square mile or 259 ha (640 acres). The area of a theoretical
township is 9324 ha (23,040 acres). Each section can be further subdivided into distinct
segments as shown in Figures 8.3 and 8.4, respectively.
© 2007 BICSI®
8-13
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Rectangular Grid System, continued
Figure 8.3
Section subdivision
N2
320 ac
80 ch
Sec.
40 ch
Sec.
All 640 ac
40 ch
40 ch
Sec. cor.
Quarter
sec. cor.
2
S
320 ac
2
E2
320 ac
ac
ch
sec
sec cor
=
=
=
=
40 ch
40 ch
4
4
4
4
NW NE NE NE
40
ac
40 ac
4
4
4
4
SW NE SE NE
40 ac
40 ac
Sec.
40 ch
40 ch
Sec.
NW4
160 ac
80 ch
40 ch
40 ch
W
320 ac
40 ch
Quarter
sec. cor.
40 ch
80 ch
40 ch
80 ch
Sec. cor.
4
20
20
SW
160 ac
SE4
160 ac
40 ch
40 ch
Acre
Chain
Section
Section corner
OSP Design Reference Manual, 4th edition
8-14
© 2007 BICSI®
Chapter 8: Right-of-Way
Rectangular Grid System, continued
Figure 8.4
Small subdivision
Section diagram showing small subdivisions
40 ch
2
4
4
N NW NE
20 ac
2
4
4
S NW NE
20 ac
NW4
2
4
4
2
2
4
4
S N NE NE
and
2
4
4
S NE NE
30 ac
NE4
4
4
SE NW
4
4
SW NE
4
4
SE NE
4
4
NW SE
NE
80
20
4
4
SW NW
2
N N NE NE
10 ac
40
80 ch
2
2
4
4
W W NE NW
10 ac
2 2
4
4
W E NE NW
and
2
2
4
4
E W NE NW
20 ac
2 2
4
4
E E NE NW
10 ac
E
2
4
4
NW NW
20 ac
2
4
4
W NW NW
20 ac
20
40 ch
Sec.
NE
4
4
SW
5
5
5
5
4
SE
4
4
SW SE
4
4
SE SE
2
2
4
4
SE4
E W SE SW
and
2
2
4
4
E W SE SW
30 ac
20
2
2
4
4
W W SW SW
10 ac
2
2
4
4
E W SW SW
10 ac
2 2
4
4
W E SW SW
10 ac
2
2
4
4
E W SW SW
10 ac
2 2 2 4
4
W W W SE SW 5 ac
4
2 2 2 4
E W W SE SW 5 ac
SW4
4
40
20
4
4
NW SW
2.52.5
ac = Acre
ch = Chain
© 2007 BICSI®
8-15
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Rectangular Grid System, continued
Another commonly used convention is that of lotting. By this method, smaller tracts could be
broken out and given a distinct reference as shown in Figure 8.5.
Figure 8.5
Legal subdivision and lotting
Part of township showing legal subdivisions and lottings
80
80
N
320 ac
2
2
Sec
W
E
320 ac
320 ac
Sec
Sec
2
S
320 ac
4
4
4
4
4
4
4
4
4
4
4
4
2
SW
160 ac
4
4
4
4
4
4
4
4
4
4
4
4
NW NW NE NW NW NE NE NE NW NW NE NW NW NE NE NE
4
3
2
1
1
SW NE SE NE
Sec
Reservation
3
4
7
8
5
4
3
2
1
2
5
6
7
8
3
12
13
11
14
10
15
2
Sec
4
4
4
4
4
1
4
4
4
4
4
4
4
4
4
SW SE SE SE SW SW SE SW
8
3
2
2
7
4
4
4
4
NW NW NE NW 2
1
4
5
4
6
9
7
6
5
8
3
7
16
tB
ef
L
Sec
8
9
1
3
4
r
4
4
SE NE
ank Rive
5
4
SW NW
1
4
Sec
nk
4
4
4
4
Ba
NW SE NE SE
6
ht
Sec
NE
NW SE NE SE NW SW NE SW NW SE
Rig
6
2
SE
160 ac
2
NW
2
5
2
NE
160 ac
2
NW
160 ac
2
4
4
4
4
4
4
SE SW SW SE SE SE
4
ac = Acre
sec = Section
Based on Figure 8.5, Lot 1, located in Section 31, could be described by a series of letters and
numbers as Lot 1, Sec 31, T.4.N., R.3.W., Third Principal Meridian, First Standard Parallel
North. This description applies to only one piece of land within the United States.
OSP Design Reference Manual, 4th edition
8-16
© 2007 BICSI®
Chapter 8: Right-of-Way
Rectangular Grid System, continued
Many variations of the rectangular grid system exist within the United States. Where lines of
ownership (e.g., land grants, Native American lands, railroad surveys) already existed,
fractional townships and fractional sections were established.
Another factor affecting the rectangular grid system is the fact that true meridians converge
at both the North and South Poles. Due to this convergence, without some type of correction,
townships would grow narrower as they continued north and wider as they continued south.
To counteract this effect, new guide meridians are established in each quadrangle. This is why
when one travels down a road that runs parallel to the section lines there is a jog to the right or
left every 39 km (24 mi).
Though widely used, the rectangular grid system is not the most accurate land measurement
system.
Mercator Projection System
Mercator projection is a mathematical method of showing a map of the globe on a flat
surface. This projection was developed in 1568 by Gerhardus Mercator, a Flemish geographer,
mathematician, and cartographer. In October 1884, 41 delegates from 25 nations met in
Washington, DC, for the International Meridian Conference. The conference established the
prime (i.e., world) meridian or the meridian passing through the principal Transit Instrument at
the Observatory at Greenwich, England to be the initial meridian. In addition, all longitude
would be calculated both east and west from this meridian up to 180°. To increase the level of
accuracy, the United States developed what is known as the State Coordinate System. Using
this system, measurements of the earth are mathematically projected onto cones or cylinders
and then flattened into planes. Using this method, a strip of land 254 km (158 mi) wide and
infinitely long could be represented to an accuracy of about 0.3 m (1 ft) in 3.2 km (2 mi).
The Canadian government established its prime meridian at the exact center of the geographic
area of Canada. All north-south mile roads east and west of this marker are labeled by the
number of miles east or west of this marker. It is located just west of Headingley, Manitoba,
and just north of the service road on the north side of the Trans-Canada Highway.
At present, two geodetic coordinate sets are commonly used throughout Australia:
•
Australian Geodetic Datum 1966 (AGD66)
•
Australian Geodetic Datum 1984 (AGD84)
For purposes of illustration in this text, the U.S. State Coordinate System is used.
© 2007 BICSI®
8-17
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
State Coordinate System
The United States established a separate system for each state. It also established a beginning
point in each state, which has been documented by a monument. From these starting points,
the north-south direction is termed the x-coordinate and the east-west direction is the
y-coordinate. Dimensions are given in feet and decimals of a foot.
Although many engineers and surveyors use this system of property description since it does
not reference the adjacent property, it has not gained popularity with the real estate
community. The state coordinate system is most often seen in conjunction with other methods
of description or as supplemental reference material.
Using the description of Lot 1 from the rectangular grid system, the previous example could
be amplified as Lot 1, Sec 31, T.4.N., R.3.W., Third Principal Meridian, First Standard Parallel
North. It can be more fully described as beginning at a point in the north line of Section 31,
said point being 52 809.55 m (173,259.2 ft) West and 547 567 m (1,796,474 ft) South and being
the northeast corner of said property.
By using the State Coordinate System in conjunction with the rectangular grid system, the
location of the property has been more accurately described (see Figure 8.6).
Figure 8.6
State coordinate system
North pole
(24 mi)
39 km
39 km
(24 mi)
(24 mi)
Check
39 km
1st standard parallel north
Principal meridian
1st guide meridian west
2nd standard parallel north
Baseline
1st standard parallel south
Longitude lines
(meridians)
Latitude lines
(parallels)
39 km
39 km
39 km
(24 mi)
(24 mi)
(24 mi)
km = Kilometer
mi = Mile
OSP Design Reference Manual, 4th edition
8-18
© 2007 BICSI®
Chapter 8: Right-of-Way
Metes and Bounds
The metes and bounds of property describes the tract with a series of lines, distances, and
bearings. The metes and bounds description begins at a well-established and documented
reference point. This point will not normally be on the tract being described. It becomes a
point of beginning, but not the point of true beginning. From the point of true beginning, the
tract is normally described in a clockwise direction around the complete perimeter of the
property. The bearing or angular direction of each line is written in terms of a compass
direction expressed in degrees, minutes, and seconds. The distances along the bearing are
expressed in terms of feet, tenths, or hundredths of a foot. All bearings are measured from a
north-south reference expressed as N or S preceding the angle. Following the angle is the
letter E or W depending on the direction from the north-south direction line. In this way, an
angle could be expressed as N 15° 12’ 15" E.“
Figure 8.7 shows the compass as it is used with land descriptions.
Figure 8.7
Use of the protractor
º
30
N
North
10
10
N
or
t
20
40
50
40
70
90 80
70
60
60
50
60
70
80
50
10
0
10
South
20
8-19
E
E
as
t
40
20
30
W
es
t
60
º
30
d
S
40
a
© 2007 BICSI®
50
h
ut
So
n
East
60
ºW
0
S7
90 80
70
Point from which
course is run
80
West
h
30
t
es
W
No
rt
h
30
20
0
d
an
an
ºW
E
0
N2
d
t
es
W
h
ut
So
d
an
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Metes and Bounds, continued
NOTE:
The direction North could be expressed in several ways. It could be in reference to
true north, having its origin at the North Pole, or in terms of magnetic North, which
is located some distance from the North Pole and varies by location. In most cases,
the North reference used will be one that has been established and documented
from previous local or regional surveys.
Using the example developed from the rectangular grid and state coordinate systems, the
description could be further amplified as Lot 1, Sec 31, T.4.N., R.3.W., Third Principal
Meridian, First Standard Parallel North. It can be more fully described as beginning at a point
in the north line of Section 31, said point being 52 809.55 m (173,259.2 ft) South and 547 567
m (1,796,474 ft) West and being the northeast corner of said property.
This description could be continued using the metes and bounds description methods to more
accurately describe Lot 1. Since the northeast corner of the tract has been established using
the State Coordinate System, it can also be used as the point of beginning for the metes and
bounds description. Therefore, the metes and bounds description would be Lot 1, Sec 31,
T.4.N., R.3.W., Third Principal Meridian, First Standard Parallel North. It can be more fully
described as beginning at a point in the north line of Section 31, said point being 52 809.55 m
(173,259.2 ft) West and 547 567 m (1,796,474 ft) South, and being the northeast corner of said
property. Thence S 2° 00’ 0" E 792.5 m (2600 ft) to a point on the east line of Sec 31, thence
S 88° 00’ 0" W 816.87 m (2680 ft), thence N 2° 00’ 0" W 792.5 m (2600 ft) to a point in the
north line of Sec 31, thence S 88° 00’ 0" 816.87 m (2680 ft) to the point of beginning and
containing 64.74 ha (159.963 ac) more or less.
OSP Design Reference Manual, 4th edition
8-20
© 2007 BICSI®
Chapter 8: Right-of-Way
Metes and Bounds, continued
At this point, three of the requirements for the description of property (location, shape, and
area) have been completed (see Figures 8.8 and 8.9).
Figure 8.8
Naming conventions for metes and bounds
Naming directions for a
metes and bounds survey
N
S 1
5°
W
S
45
°
(2
8
9
ft
0
)
°
m
R
E
=
m
S 80
° E
8
.5
S 85° W
W
=
N 80
° W
E
°
60
N
° E
N 80
W
1
3
.4
°
=
45
A
N
N 4° E
P
(4
4
.0
ft
)
Mapping a curve
E
Q
S
Moving in a clockwise direction from the
point of beginning, set the center of a
circle compass (see above) on each
corner of the parcel to find the direction
of travel to the next corner
A = Length of the arc. (Some maps
use the letter "L")
R = Radius of the circle necessary to
make the required arc (shown
here by the broken lines)
= Angle necessary to make the arc
(i.e., the angle between the
broken lines)
ft = Foot
m = Meter
© 2007 BICSI®
8-21
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Metes and Bounds, continued
Figure 8.9
Metes and bounds
N
" E
' 00
0° 0
8
N
ft) Monument
152
m (
3
.
46
N 4° 11' 8" E
60.8 m (199 ft)
W
00"
° 0'
S 85
ft)
(151
46 m
ft = Foot
m = Meter
OSP Design Reference Manual, 4th edition
S 15°
0' 00
" W
49 m
(160
ft)
Permanent
reference mark
Point of
beginning
S 80°
0' 00
" E
55 m
(180
ft)
8-22
© 2007 BICSI®
Chapter 8: Right-of-Way
Subdivision Plat and Description
In the case of the subdivision, the description is not in narrative form, but rather in the form of
a drawing or plat where all of the boundaries are identified and tied to the original tract of land
being subdivided. Using the previous example, the narrative description identifies the larger
parcel while a metes and bounds drawing, called a plat, identifies the streets, lots, and
easements within the tract (see Figure 8.10).
Figure 8.10
Subdivision plat and description
N
65.8 m (216 ft)
Court
R 18.3 m (60 ft)
12
(4 m
0.
0
ft
)
73 m
(240 ft)
47.7 m (156.5 ft)
Lot 3
51
.8
m
(1
70
ft
)
Lot 4
Lot 2
123.9 m
(406.5 ft)
S 00° 00' 01" W
70.6 m (231.6 ft)
17 m (57 ft)
55.5 m (182.1 ft)
76 m (250 ft)
R 18.3 m
(60 ft)
Lot 1
33.7 m
(110.5 ft)
45.8 m (150.0 ft)
12 m (40 ft)
49.4 m (162 ft)
R 12 m (40 ft)
41.5 m (136 ft)
Lot 5
Wildflower
53.3 m (1755 ft)
N 00° 00' 01" E
143.7 m
(471.5 ft)
73 m (240 ft)
24 m
(80 ft)
19.8 m
(65 ft)
N 89° 59' 59" E
118.3 m (388 ft)
24 m
(80 ft)
93.9 m (308.1 ft)
229.2 m
(752 ft)
118.4 m (388.4 ft)
S 89° 59' 59" W
SE Corner of section 4
T14N, R2E, 4th principal meridian
Plat of block 31, Painted Hills Tract,
recorded in map book 192
page, at the ABC county records
office, state of XYZ
ft = Foot
m = Meter
© 2007 BICSI®
8-23
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Centerline Description
The centerline description (see Figure 8.11) is one of the primary methods used in the
description of an easement. Rather than describe a rectangle, when the easement is of
uniform width, only the centerline is described by the metes and bounds method. The width of
the easement is stated as being x-number of feet on each side of the line.
Figure 8.11
Centerline description
N
Hidden River Parkway
Lot 1
Lot 3
Lot 2
2.3 m
(7.5 ft)
S 89° 59' 59" W
C
L
137 m (450 ft)
2.3 m
(7.5 ft)
Lot 4
Lot 5
Lot 6
ft = Foot
m = Meter
OSP Design Reference Manual, 4th edition
8-24
© 2007 BICSI®
Chapter 8: Right-of-Way
Point Description
This type of metes and bounds description is also used to describe an easement. In the point
description is a centerline description in which each point of change in alignment along the
perimeter of the tract is referenced to the centerline (see Figure 8.12).
Figure 8.12
Point description
2.3 m
(7.5 ft)
S 80º 0'
00" E
27.4 m (9
" E
' 00
ft)
0º 0
(150
N 8
m
8
.
5
4
0 ft)
S 1
5º
0' 0
0" W
125
ft
C
L
2.3 m
(7.5 ft)
2.3 m
(7.5 ft)
N
2.3 m
(7.5 ft)
C
L
= Center line
C
L
ft = Foot
m = Meter
© 2007 BICSI®
8-25
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Reference Description
The reference description is primarily used in urban areas or rural subdivisions where the tract
has been subdivided and each lot given a number. Once the original plat and description has
been recorded, the description of each individual lot can be referenced to the original plat.
A typical description would be Lot 34, Block 14-B, Woodhaven Country Club Estates, 3-B
filing, an Addition to the City of Fort Worth, Tarrant County, Texas, according to the plat
recorded in Volume 388/97, Page 25, Plat Records, Tarrant County, Texas.
Summary of Property Descriptions
Property descriptions are an important part of R/W acquisition. The requirement of having a
complete and accurate description of the property cannot be overemphasized.
The description identifies a piece of property to the extent that any competent person could
identify it at any time in the future. It also satisfies all of the legal requirements for the transfer
of land. The primary systems in use today are the U.S. rectangular grid system, the State
Coordinate System, and the metes and bounds system of land identification.
With the aid of these systems, three of the five requirements usually considered a part of the
property description are satisfied. The remaining two components concern the intent of the
seller and buyer and the establishment of ownership.
OSP Design Reference Manual, 4th edition
8-26
© 2007 BICSI®
Chapter 8: Right-of-Way
Real Estate Law
To determine who owns a parcel of property, the basic types of ownership associated with
real estate must be understood.
Interests in real estate are called estates. An estate is defined as the nature, quality, degree, or
extent of a person’s interest in real property. Although numerous types of interests exist, the
most common types are:
•
Fee ownership.
•
Leasehold.
•
Easements.
•
License.
•
Life estate.
Fee Ownership
Fee ownership is the highest and most complete type of ownership. Fee ownership is also
termed in fee, in fee simple, or in fee simple absolute. With fee ownership, the person
possesses all rights to the property and has no limitations as to what they could be done with
the property.
© 2007 BICSI®
8-27
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Real Estate Law, continued
Leasehold
A lease is a contract that grants the lessee (i.e., tenant) the right to occupy the property of the
lessor (i.e., landlord) for a specified period of time. As a result of this contract, the lessee
becomes, in fact, the owner of an interest in the land or leasehold interest.
Easement
An easement is defined as the right acquired by one entity (e.g., person or company) to use
the property of another for a special or particular use. In OSP, the purpose of obtaining an
easement is for the placement of information transport systems (ITS.) The term could be as
long as required by the purchaser to support the ITS requirement.
An easement also gives the holder the right:
•
Of ingress/egress (entering/exiting).
•
To place and maintain the facilities being proposed.
A landowner who grants an easement is precluded from building a structure of any kind on the
easement but retains the right to use the land within certain limits to:
•
Plant grass.
•
Farm.
•
Otherwise use the property.
R/W is a type of easement giving one person or company the right to pass over the land of
another. By common usage, the term R/W could refer to the right or the strip of land on which
the right is located.
License
A license is an interest in property for a limited time and purpose. Normally, unauthorized
entry onto someone else’s property would be considered trespassing. When the entry is
authorized, the person entering is said to have a license. For example, when someone buys a
ticket to see a motion picture, that person has, in fact, purchased a license for a seat in the
theater for that date and that motion picture.
Life Estate
This interest in real property could be created by deed or will. The owner of the life estate is
allowed to use the property for the duration of their life. Upon the owner’s death, all rights
revert to the person granting the life estate, their heirs, or assigns. The person who had the life
estate has no further interest in the property.
OSP Design Reference Manual, 4th edition
8-28
© 2007 BICSI®
Chapter 8: Right-of-Way
Real Estate Law, continued
Ownership
In addition to estates in land, there are also types of ownership. The primary types of
ownership are:
•
Single ownership.
•
Joint ownership.
–
Joint tenancy, including tenancy by entirety, community property, dower, and curtesy.
–
Tenancy in common.
Single Ownership
When one person is the sole owner of a parcel of real estate, that person is known as the
owner in severalty. In the majority of cases, ownership is not this restrictive but is shared by
one or more persons.
Joint Ownership
Two types of joint ownership are joint tenancy and tenancy in common. Each type creates a
difference in the property.
Joint Tenancy
A joint tenancy is one in which two or more persons hold an estate. Upon the death of one,
the right to that portion reverts to the remaining person without creating a new document or
deed. It is assumed that the joint tenants individually own the entire property. Some states
have abolished joint tenancy, allowing the property of the deceased to pass to their heirs.
Other types of joint tenancy are created between married persons. They are tenancy by
entirety, community property, dower, and curtesy.
In the case of tenancy by entirety, some states treat a husband and wife as one person.
Therefore, upon the death of one spouse, unless another intent is shown in the deed, the
survivor is entitled to the entire property. This right only exists if the couple is married at the
time of purchase.
Some states have provided for property that a couple acquires during marriage as opposed to
separate property that each person had prior to the union. Separate property could also include
property acquired by one spouse after marriage as a gift, inheritance, or conveyed by one
spouse to the other. In addition, interests, rent, royalty, or profit from the separate property
would remain separate property as long as it is not commingled with community funds.
Dower is the wife’s interest in the estate of her husband, while curtesy is the husband’s
interest in his wife’s estate.
© 2007 BICSI®
8-29
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Real Estate Law, continued
Tenancy in Common
Tenancy in common is another type of multiple ownership in which each owner has an
undivided share in the property, and at any time, action could be brought to divide the property.
Upon the death of one of the owners, a new ownership group is formed consisting of the
original owners and the heirs of the deceased. In a tenancy in common, there is no right of
survivorship as there is in other types of joint tenancy.
Title Transfer
The primary methods and documentation used to transfer title to real estate are:
•
Escrow.
•
Conveyance.
•
Grant or warranty deed.
•
Quitclaim deed.
•
Bargain and sale deed.
•
Patent.
•
Mortgage and deeds of trust.
•
Contract of sale.
Escrow
In today’s market, an escrow company handles the majority of real estate transactions. An
escrow holder is a third party who has been instructed by both the seller and the buyer about
conditions under which the transfer is to be completed. Once the conditions have been fulfilled
by both parties, the escrow holder has the deed delivered and recorded and delivers the funds
to the seller.
Conveyance
An interest in real property is transferred from the seller to the buyer by a written document
called conveyance, more commonly known as deed. The requisites for a valid deed are:
•
A written instrument containing the names of the grantor and grantee, operative words of
conveyance, and sufficient legal description to unmistakably identify the property.
•
Capable parties—The escrow company must be satisfied that the grantors are competent
to grant and that the grantees are capable of receiving title (e.g., the grantee is a living
person or entity that can hold title to real property in its name).
OSP Design Reference Manual, 4th edition
8-30
© 2007 BICSI®
Chapter 8: Right-of-Way
Real Estate Law, continued
•
Legal transfer of property—As a rule of title practice, a title company would decline to
insure an attempted conveyance of the expected interest of an heir apparent.
•
Proper execution of the deed—Although slight defects in the execution of an instrument
will not necessarily impair its validity, high standards of care and thoroughness will prevent
defects. Be certain that the instruments are signed in ink exactly as the names are typed.
•
Delivery and acceptance of the deed—Questions on these points usually arise in situations
where the intent of the parties is not clear. The requisite of delivery is not likely to become
a problem in an escrow transaction. A number of factors could have a bearing on the
conclusion as to delivery, but questions on this point are a rare occurrence.
The two most common types of deeds used in the United States are the grant or warranty
deed and the quitclaim deed.
Grant or Warranty Deed
The grant or warranty deed protects the buyer in that the seller guarantees that the grantor
has not previously transferred the title to another person, and the property is free of any
encumbrance or defect in the title that would affect the validity of the transfer. Grant or
warranty deeds are broken down into two subcategories—general warranty deed and special
warranty deed. In a general warranty deed, the grantor warrants the property in total, while
the special warranty deed only warrants the property against defects after the grantor
acquires the property.
Quitclaim Deed
This type of deed only conveys the property rights that the grantor has at the time of sale.
This deed is commonly seen in a divorce settlement when one of the parties retains the
common real estate.
NOTE:
The granting of a quitclaim deed does not warrant that the person granting the deed
has or had any interest in the property.
Bargain and Sale Deed
The bargain and sale deed is a hybrid between a warranty deed and a quitclaim deed. This
deed specifies a monetary consideration and states the transfer of title to the buyer. It may or
may not offer any type of warranty and could purport to convey to the buyer more interests in
the property than the grantor owns.
Patent
A state or the federal government uses this type of instrument in the conveyance of title to
public land. When researching the ownership of property, the patent is the base document
upon which the chain of title is based.
© 2007 BICSI®
8-31
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Real Estate Law, continued
Mortgage and Deeds of Trust
This type of deed serves primarily as a security interest in the property. The main difference
between a deed of trust and a mortgage is that a deed of trust could provide for the transfer
of the borrower’s interest in the property to a party called a trustee. The lender could call
upon the trustee to sell the secured property should the borrower be unable to repay the loan.
The mortgage creates a security interest in the property, but the effect of the document varies
by location. In many states, the mortgage is considered to give the mortgagee title to the land.
In other states, it is considered a lien or encumbrance in favor of the mortgagee. A mortgage
is an agreement between the mortgagor (i.e., borrower) and the mortgagee (i.e., lender).
Therefore, to assert the right, the mortgagee must initiate a lawsuit for foreclosure.
Contract of Sale
The contract of sale could be one of two types. The first type provides for immediate transfer
of ownership of the property by the buyer. The price is paid in cash or cash with the balance
paid by some type of promissory note. The second type is a land installment contract where
the buyer does not acquire a recordable interest in the property until all payments have been
made and the seller agrees to convey title to the buyer. In addition to the outright purchase of
land, two other methods of land acquisition exist in the United States—accretion and adverse
possession.
The term accretion is normally applied to land that lies adjacent to a navigable body of water
(e.g., the Mississippi River). When the natural action of the water deposits soil on adjacent
lands, the process of accretion forms additional land. If the tract were sold, the accreted land
would be included in the sale, even though it was not a part of the original tract. On the other
hand, if the land is washed away and deposited elsewhere, the owner loses title to that portion
of the land.
Adverse Possession
Adverse possession goes back to the theory that possession is nine-tenths of the law. To
acquire land by adverse possession, the possession must be hostile, actual, notorious,
exclusive, continuous, and under claim of title. To be valid, the person claiming the property
must continually occupy the land for the specified amount of time in such a manner that the
original owner can observe that it is in possession in opposition to the owner’s claim. One
example of adverse possession is when a fence line becomes the property line rather than the
original lot or survey line.
Up to this point the original question remains, how does one establish ownership? Normally,
title to land can be established through public records and developing what is termed a chain
of title.
OSP Design Reference Manual, 4th edition
8-32
© 2007 BICSI®
Chapter 8: Right-of-Way
Real Estate Law, continued
Eminent Domain (Condemnation)
As the ownership of OSP is not limited to private entities, but can be owned by governmental
agencies as well, no discussion of R/W acquisition would be complete without a discussion of
eminent domain. Eminent domain can be defined as the right or power of public and
semipublic agencies to take private property for public purposes without the owner’s consent
on payment of just compensation. The power of eminent domain is commonly referred to as
the right of condemnation. Though rooted in common law, the right of kings, the basis for the
right of eminent domain in the United States is found in the final clause of the Fifth
Amendment to the U.S. Constitution.
No person shall be held to answer for a capital, or otherwise infamous crime,
unless on a presentment or indictment of a Grand Jury, except in cases arising in
the land or naval forces, or in the militia, when in actual service in time of war or
public danger; nor shall any person be subject for the same offence to be twice put
in jeopardy of life or limb; nor shall be compelled in any criminal case to be a
witness against himself, nor be deprived of life, liberty, or property, without due
process of law; nor shall private property be taken for public use, without just
compensation. (Emphasis added.)
While the statement, “…nor shall private property be taken for public use, without just
compensation” applies to the federal government, language similar to this exists in many state
constitutions. In states where it has not been included, eminent domain is based on case law.
In addition to the use of this power by a governmental agency, this power has also been
expended to utility companies, as their availability throughout an area has been deemed for the
public good. This power thus prevents any individual from withholding their permission to
place OSP upon their property. An example of this could be the placement, by a city, of an
optical fiber LAN in support of city emergency services (e.g., 911). Once the route has been
established and verified that the only method available to bridge the gap is through this
property, the designer of such a network would turn the matter over to the proper city agency
to acquire the R/W.
Once the ownership of the parcel of land and the amount of land required for the easement
are determined, the value of the easement needs to be established. The amount that one is
willing to pay and the amount that the owner desires are probably not the same. It is,
therefore, necessary to have an appraisal of the partial acquisition.
NOTE:
© 2007 BICSI®
In June 2005, the U.S. Supreme Court, in a 5-4 majority, ruled that local governments may force property owners to sell out and make way for private economic
development when officials determine that it would benefit the public, even if the
property is not blighted and the new project’s success is not guaranteed.
8-33
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Chain of Title
In most areas, an abstract of title is available from either an attorney or an abstract company.
In this instance, a researcher has verified the public record and traced the history of the
property back to the original grant or patent. The abstract of title is a summary of this
research. Additionally, title insurance companies located throughout the country make it
possible for a person acquiring property to buy an insurance policy that will insure the title to
the property.
Based on this information, and going back to the earlier example, the property description
would be further amplified as Lot 1, Sec 31, T4N, R3W, Third Principal Meridian, First
Standard Parallel North. It can be more fully described as beginning at a point in the north line
of Section 31, said point being 52 809.55 m (173,259.55 ft) South and 547 567 m (1,796,474 ft)
West, and being the northeast corner of said property. Thence S 2° 00’ 0" E 792.5 m (2600 ft)
to a point on the east line of Sec 31, thence S 88° 00" 0' W 816.9 m (2680 ft), thence
N 2° 00’ 0" W 792.5 m (2600 ft) to a point in the north line of Sec 31, thence S 88° 00’ 0"
816.9 m (2680 ft) to the point of beginning and containing 64.74 ha (159.963 acres) more or
less. Being the same premise conveyed to Philip Janeway by deed recorded in Book 1279, at
page 965, Jefferson County, State of Indiana.
At this point, the property description is complete. The intent of the seller and the buyer would
normally be spelled out in the beginning of the deed document. The intent would state the
name of the seller, the buyer, and the consideration given for the parcel.
In addition to the various types of deeds, certain restrictions could be written into the deed that
restricts the use of the land. These are known as restrictions, covenants, and conditions.
OSP Design Reference Manual, 4th edition
8-34
© 2007 BICSI®
Chapter 8: Right-of-Way
Restrictions, Covenants, and Conditions
The use of property can be limited or restricted in one of two ways. In most metropolitan
areas, zoning laws set certain restrictions. Additionally, the developer could have incorporated
additional restrictions at the time the land was subdivided. These restrictions could apply to the
manner in which the utilities are placed. For example, it could require all utilities to be
underground. Due to this restriction, if an aerial telecommunications lead was placed past the
property, it would have to be buried for this portion of the project. Changes to the covenants
would require the approval of all owners of the subdivision. Additional restrictions could also
apply in the form of liens and encumbrances.
© 2007 BICSI®
8-35
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Liens and Encumbrances
An encumbrance can be defined as any lien, claim, or liability attached to the land.
Encumbrances could be in the form of a mortgage, unpaid taxes, a mechanic or vendor’s lien,
a judgment, or even an easement or R/W previously granted on the property. A lien is more
restrictive than an encumbrance in that the debt owed could require the sale of the property
with the proceeds going to the lien holder. The term encumbrance can be defined as anything
that affects or limits the fee simple title to property.
Appraisers
The Appraisal Foundation, subset of IRWA, certifies appraisers and requires that they have
training in:
•
Influences on real estate value.
•
Legal considerations in appraisal.
•
Types of value.
•
Economic principles.
•
Real estate markets and analysis.
•
Valuation process.
•
Property description.
•
Highest and best-use analysis.
•
Appraisal math and statistics.
•
Sales comparison approach.
•
Site value.
•
Cost approach.
•
Income approach.
•
Valuation of partial interests.
•
Appraisal standards and ethics.
•
Narrative report writing.
Once the decision has been made to acquire an easement, the process is broken down into
four phases:
•
Engineering
•
Legal
•
Appraisal
•
Negotiation
OSP Design Reference Manual, 4th edition
8-36
© 2007 BICSI®
Chapter 8: Right-of-Way
Appraisers, continued
Engineering
Where possible, several routes should be considered. They could be prioritized based on the
site survey. Once this is accomplished, the engineering phase can begin. First and foremost is
the requirement to have a complete and accurate description of the property upon which the
easement is located, together with an accurate description of the easement. The description
should be written so it can be clearly recognized by a competent person at any time in the
future. It should also satisfy the legal requirement for the transfer of an interest in real estate.
The description of the property as stated on the deed should fulfill this requirement. The
location of the easement on the property must also meet this same requirement. The licensed
land surveyor can prepare this description. It is also advisable to have both the written
description along with a plat (drawing) of the easement. Once these documents have been
prepared, the next phase of the acquisition process can begin.
Legal
The legal aspect of R/W acquisition can be broken down into two distinct segments:
•
Establishing ownership of the parcel of land upon which the easement is located
•
Preparing the easement document (i.e., deed)
The chain of title can be accomplished by an attorney or through an abstract company. Ensure
that the deed is free from any defects and/or encumbrances.
R/W forms are available and can be prepared by an R/W agent working under the direction of
an attorney with the R/W company. If the form is prepared in house, an attorney should
review and approve the form. See Chapter 2: Legal Considerations for the OSP Designer for
more information.
CAUTION:
When writing the description, the intended use should be stated as generally
as possible. If the original purpose of the easement is placement of a 25-pair,
self-supporting aerial cable and is stated as such, the size could not be
increased or the cable could be replaced with optical fiber without obtaining a
new easement. The purpose is better stated as placement of aerial
telecommunications cables.
Appraisal
The appraisal of easement, also known as appraisal of partial acquisitions, is concerned with
two aspects of land valuation:
© 2007 BICSI®
•
Value of the land before the easement
•
Value of the land after it has been encumbered by the easement
8-37
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Appraisers, continued
Land is a limited resource. The land required to tie together two portions of a complex is even
more limited. The valuation of property is based on several key factors:
•
Supply and demand
•
Change of use
•
Substitution
•
Highest and best use
•
Anticipation
Supply and Demand
A basic rule of physics states that the shortest distance between two points is a straight line.
The rule could also be applied to the route between two properties. However, the land
available for the placement of OSP between the two is a limited resource. The designer
should assume that the best route is along a public road. If space is available on public land,
then an application for a permit from the AHJ is required. However, if this space is occupied
by other utilities, the only recourse is the use of private land or development of an alternate or
longer route.
Change of Use
In many instances, the requirement for OSP is driven by change. The client is expanding their
facility. The same change could take place throughout the area. Land that is used as
agricultural land could change to industrial or commercial. In this case, the value of the land
also increases relative to its supply. For example, if the shortest route is directly across an
agricultural field and is placed at a sufficient depth, OSP will not impact the use of that
segment of the field for agricultural purposes. If the use of that same piece of land were
changed to an industrial use, then the location of the easement may have a definite impact on
the location of a building.
Substitution
Substitution is another approach that an appraiser uses to establish value. In this case, a
similar and equal piece of property is compared to the piece over which OSP will be placed.
In the substitution process, all other factors are assumed to be equal; the one with the lowest
price substitutes all others.
OSP Design Reference Manual, 4th edition
8-38
© 2007 BICSI®
Chapter 8: Right-of-Way
Appraisers, continued
Highest and Best Use
The highest and best use of the property may not be the current use of the land but the use
that will provide the highest return to the owner. For a tract of land 8 km (5 mi) outside the
city limits, the highest and best use could be agricultural. Should the land be incorporated into
the city, the highest and best use could change from agricultural to single-family dwellings.
This change would greatly enhance the value of the property.
Factors that could impact the highest and best use are zoning and private restrictions that may
have been placed on the land. It is, therefore, advisable that these factors be considered when
designing the proposed placement of an easement. As in the earlier example, if the easement
is placed where it would not impact the highest and best use of the land, its impact on the
value of the land is minimal.
Anticipation
To the owner or buyer of real estate, the value of the land may not be what it is capable of
producing today but rather what it will produce in years to come. Because of this, one of the
functions of the marketplace is to derive today’s price for the right to obtain future
satisfaction.
Based on these principles, the appraiser must measure this value in terms of the compensation
required for the property together with any compensable damages that could occur to the
land. One example of a compensable damage would be the requirement to cut a driveway,
which would be replaced. The owner or tenant could require additional damages for the
inconvenience caused during the construction period.
Aesthetics is another aspect that must be considered. In an area where aerial construction is
common, one more pole line may not have an aesthetic impact. However, in an area where all
utilities are underground, an aerial line could be unacceptable. After the value has been
established for each route, a decision can be about the route that will be most cost-effective
for the project. Following this decision, the fourth and final phase, negotiation with the
landowner for acquisition of the easement, can commence.
Negotiation
In the area of easement acquisition, negotiation is the most crucial phase of the project. If the
negotiation with the owner is not completed in a successful manner, all of the actions
completed prior to the negotiation are lost. Therefore, negotiation can be defined as the
process by which property is sought to be acquired through discussion, conference, and final
agreement on the terms of a voluntary transfer of property.
© 2007 BICSI®
8-39
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Appraisers, continued
Most textbooks on the subject of negotiations will list at least three types of negotiation
methods:
•
Bargaining
•
Attitudinal
•
Integrative
Of these three types, the one most people think of when they hear the word negotiation is
bargaining. A good example of bargaining negotiation is the negotiation process between labor
and management. The problem with this concept is that bargaining negotiation is also thought
of as a win-loss situation for one of the parties. Therefore, bargaining negotiation has a very
limited use in R/W acquisition. Remember, for any sale to take place there must be a willing
seller and a willing buyer.
In the case of the easement acquisition, there is a willing buyer, but not necessarily a willing
seller. A better approach could be to use a combination of attitudinal and integrative
negotiations. In the attitudinal approach to negotiation, a set of ground rules is established
between both parties and a sense of trust could develop between the two. Once this trust is
developed, the integrative phase can begin.
Integrative negotiation, sometimes called a win-win situation, is more of a problem-solving
approach between the buyer and the seller. By using this method, the buyer understands the
seller’s problems and vice versa. In most cases, an agreement may be reached that will meet
the needs of the buyer, and, at the same time, minimize any negative effects for the seller.
Due to the preconceived ideas that most people possess, it is incumbent on the buyer to
approach this phase with caution.
Depending on the buyer’s relationship with the landowner, the negotiation could be
accomplished by the buyer or through a third party, such as an R/W agent or an attorney.
After the easements have been acquired, the easement documents must be recorded in the
same fashion as any other real estate transaction. In addition, the overall environmental and
aesthetics impact of the project must be considered.
Private Right-of-Way (R/W)
Private R/Ws are usually obtained by executing with the property owner a R/W acquisition
document, called an easement. Easement documents detail a specifically defined route along,
under, over, or across the property with which OSP facilities are placed.
The primary reasons for obtaining a private R/W easement are to:
•
Decrease the likelihood of having to move the physical plant in the future.
•
Restrict the owner from certain types of construction on the property contained in the
easement that might interfere with the physical plant.
OSP Design Reference Manual, 4th edition
8-40
© 2007 BICSI®
Chapter 8: Right-of-Way
Obtaining and Recording a Private Easement
In the United States, the laws of each state are different regarding the obtaining and recording
of easements; however, there are several key factors that apply to all easements.
It is crucial to determine the correct owner of the private property before obtaining an
easement. Failure to do so can render the easement invalid and cause loss of money paid for
the easement.
The easement must be executed between the actual owner of the physical plant seeking
permission to enter the property and the owner of the property (or the person or company
who holds power of attorney for the owner). A contractor can assist in preparing and
recording the easement, but the plant owner must perform the actual execution.
Private R/W acquisitions are not legal unless the person or company requesting the easement
pays a monetary fee to the owner of the property. The amount can vary depending on:
•
The details of the easement.
•
How much property is being tied up.
•
Terms and conditions of the easement.
Independent parties must witness the execution of the easement, and the executed document
must be recorded at the Clerk of the Court’s office for the county in which the property is
located. Failure to record the document could result in the document being ruled invalid if
conflicts occur.
The executed and recorded easement documents should be included in the records of the
project.
© 2007 BICSI®
8-41
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Contents of the Private Easement Document
Easement Document
The details contained in the easement document are related to the type of physical plant
planned for the project:
•
Direct-buried
•
Underground
•
Aerial
•
Combination of the above
An easement application should contain a minimum of two documents including:
•
The terms and conditions of the easement. Legal counsel should prepare these with the
assistance of the consultant.
•
A detailed engineering sketch indicating prominent features and a legal description of the
property, along with details about any adjacent public R/W such as:
–
Road names and numbers.
–
Shoulder width.
–
Sidewalk, curb, and gutter locations.
–
Significant drainage structures.
–
North arrow.
–
R/W width.
–
Exact location of the proposed utility with respect to property lines.
–
Nearest intersecting road on the public road system, if available.
–
Any unusual issues or arrangements for use of the property.
OSP Design Reference Manual, 4th edition
8-42
© 2007 BICSI®
Chapter 8: Right-of-Way
Permit Information
State Highway Permit
The following information about obtaining an R/W illustrates, in general, the terms and process
involved in obtaining a public R/W permit. Other states’ requirements vary but are essentially
similar.
Application
Normally, the application package is required to include a(n):
•
Permit application (see Example 8.1). This is a formal application signed by the applicant
and, if approved by the DoT, it summarizes information about:
–
Applicant (name, address, and telephone number).
–
Highway involved (county, road/route number, and road name).
–
Type of public service line.
–
Description of the location of the line on the highway.
–
Any special provisions tied to the approval of the permit.
•
Key map (see Figure 8.13). This is a state highway map indicating the general location of
the R/W. The area containing the work must be detailed along or across the public roads
affected by the R/W.
•
Engineering sketch indicating roadway features such as:
–
Pavement width.
–
Shoulder width.
–
Sidewalk, curb, and gutter locations.
–
Significant drainage structures.
–
North arrow.
–
R/W width.
–
Exact location of the proposed utility with respect to the roadway centerline and
nearest intersecting road on the state system.
NOTE:
© 2007 BICSI®
In some cases, submission of a completed set of construction drawings will
suffice for the above requirements.
8-43
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
State Highway Permit, continued
Example 8.1
Typical state permit application
State Department
of Transportation
0199 (02/99)
THIS SPACE FOR STATE USE ONLY
Any Phone Co.
Anyone Installation Co.
123 Telephone St.
456 Dig Dr.
Bell
XX
A.G. Bell
XXX-XXX-XXXX
#72
XXXXX
Cable
XX
B.K. Fill
XXX-XXX-XXXX
36
County Line Rd.
07/15/XX
Backhoe
7 2
782
09/15/XX
4 5
XXXXX
Conduit
X
X
Install 18-strand optical fiber cable from pole #4380 to pole #4405
under state highway #72. Directional bore will be used under the
highway with a minimum depth of 48".
XXXXX
XXXXX
XXXXX
A.G. Bell - Eng. Mgr.
XX/XX/XX
XX-XXXXXXX
STATE USE ONLY — DO NOT WRITE BELOW THIS LINE
APPRROVED FOR STATE DEPARTMENT OF TRANSPORTATION BY
OSP Design Reference Manual, 4th edition
8-44
© 2007 BICSI®
Chapter 8: Right-of-Way
State Highway Permit, continued
Figure 8.13
Associated construction drawing for state permit application
Direct bury 18-strand optical fiber
cable from west side of pole #4380
for 44.2 m (145 ft) in a southwest
direction, then in a southeast direction
across State Highway 72 to pole #4405.
Use directional bore under State
Highway 72 with 51 mm (2 in) plastic
duct. Run optical fiber cable in duct
under highway. Ensure 1.2 m (4 ft) inch
minimum depth under highway.
44.2 m (145 ft)
#4380
B
18-Fiber
4-Fiber
P
ve
w
a
y
Po
o
l
Existing
House
D
ri
in
B
e
P
Gas
G
a
ra
g
e
in
e
3/8 Copper
gas line
(propane)
Propane
R
W
10 m (33 feet)
BLKTP
Centerline
State Highway 72
238.4 m (782 feet)
to County Line Road
GRVL
B
Ditch line
10 m (33 feet)
R
104.5 m
(343 ft)
W
Existing
Existing fiber route
(direct-buried)
N
House
4-Fiber
18-Fiber
#4405
B
B
BLKTP
ft
GRVL
in
m
mm
R/W
=
=
=
=
=
=
=
=
=
Future buried cable
Buried cable
Blacktop
Foot
Gravel
Inch
Meter
Millimeter
Right-of-way
© 2007 BICSI®
8-45
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
State Highway Permit, continued
Approval Process
The permit approval process consists of the:
•
Applicant submitting completed forms to the appropriate city/county/state office or
appropriate AHJ.
•
Resident maintenance engineer and district construction engineer reviewing the forms.
•
Approval and return of the permit to the applicant with the approved signatures, provided
that all details were submitted and consistent with DoT policies.
NOTE: Even if not required, it is a good policy to notify the DoT prior to beginning work.
Enforcing the Permit
The local AHJ or DoT engineer responsible for the job may visit the site during the work to
ensure conformance with the permit. A copy of the permit must be on the job site during
work. If the DoT engineer visits the site and a copy of the permit is not available, the engineer
has the right to shut down the work until a copy is available.
Railroad Right-of-Way (R/W)
Railroad R/Ws are properties owned by rail companies and used for the construction and
maintenance of the companies’ tracks and buildings. Though privately owned, rail companies
are granted much greater power over land use and acquisitions than other private landowners.
In the United States, this power was granted by federal legislation passed during the 1800s
and early 1900s.
Railroad R/Ws are obtained in a manner similar to public R/Ws.
Railroads have predetermined limits onto their properties, and their rules are much more
stringent than for many public agencies. The details required for their permits are also more
specific as discussed below.
Railroad Permit
Each railroad company’s requirements are different. The engineering office at the corporate
headquarters of the railroad company can usually provide the information required for
obtaining permits or determine the specific company location that can provide this information.
OSP Design Reference Manual, 4th edition
8-46
© 2007 BICSI®
Chapter 8: Right-of-Way
Railroad Permit, continued
Application
The applicant must prepare a letter transmitting the permit application to the designated
railroad system superintendent. This letter must indicate the location of the proposed railroad
crossing by milepost number and footage north, south, east, or west of the milepost as
appropriate and any discernible or identifiable crossroads.
The railroad can require a formal agreement between the applicant and railroad. If that
occurs, the applicant should obtain legal counsel to assist in the preparation of this agreement.
Liberal time should be allowed for railroad permit approval.
Permit Approval and Starting Work
Work can begin when the approved permit is received from the railroad. A copy of the
approved permit should be kept on the job site. Failure to do so could result in the railroad
inspector’s halting the job and revoking the permit. In most cases, a railroad inspector is
required on all projects This cost could be invoiced to the permit applicant.
Upon Completion of Work
When the work is completed, the applicant must:
•
Send a letter to the railroad indicating the day, month, and year the work was completed.
•
Advise the railroad of any changes in crossing constructions.
Retention of Records
The applicant must keep a copy of all correspondence relative to the railroad permit on file as
long as the applicant owns the physical plant.
Sale of Physical Plant
If the physical plant is to be sold, the railroad shall be notified in writing. The railroad could:
•
Place additional requirements on the new owner prior to approval of the sale.
•
Require the physical plant be removed from the railroad’s R/W.
•
Require the proposed buyer to execute a new permit.
•
Change the cost of occupancy to the new customer.
Special Requirements for Direct-Buried or Underground Plant
If the physical plant is a direct-buried or underground plant, a casing must be installed under
the tracks to house the plant and its associated structures. The casing must extend beyond:
© 2007 BICSI®
•
Both rails of a single track.
•
The outside rail of the outside tracks, if there are multiple tracks.
8-47
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Railroad Permit, continued
Check with railroad permitting authority for exact distances.
See Figures 8.14 and 8.15 for more information on special requirements for direct-buried or
underground plant:
•
Figure 8.14 shows the required length of casing for various crossing angles.
•
Figure 8.15 shows the layout and relevant dimensions for a railroad crossing.
Address questions regarding railroad crossings to the appropriate railroad system superintendent.
Figure 8.14
Casing lengths for various railroad crossing angles
0.76 m (2.5 ft)
0.76 m (2.5 ft)
4.6 m (15 ft)
4.6 m (15 ft)
40°
Rail
Rail
30°
50°
60°
70°
80°
90°
85°
75°
65°
55°
45°
35°
Angle
Length of Casing
90°
85°
80°
75°
70°
65°
60°
55°
50°
45°
40°
35°
30°
10.7 m (35 ft)
10.8 m (35.5 ft)
11 m (36 ft)
11.1 m (36.5 ft)
11.4 m (37.5 ft)
11.7 m (38.5 ft)
12 m (40 ft)
13.1 m (43 ft)
14 m (46 ft)
15.1 m (49.5 ft)
16.6 m (54.5 ft)
18.6 m (61 ft)
21.3 m (70 ft)
OSP Design Reference Manual, 4th edition
8-48
© 2007 BICSI®
Chapter 8: Right-of-Way
Railroad Permit, continued
Figure 8.15
Layout of a railroad crossing
A
A
R.R. R/W
4.6 m (15 ft)
N
4.6 m (15 ft)
al
der
r fe er
o
e
b
t
Sta e num
t
rou
Minimum
Minimum
Milepost
E
F
D
See Note
W
. R/
Hwy
B
B
R.R. R/W
Variable dimensions:
A = Width of R/W
B = Length of encasement
C = Length of encroachment
D = Distance from milepost
E = Distance from pavement
F = Angle of crossing
G = Depth of casing
C
To (nearest station)
Hwy. surface
Proposed physical plant
and casing on R.R. R/W
Subgrade
Profile
G
Drainage pipe where existing
305 mm (12 in) minimum (must
be 889 mm (35 in) if open ditch)
Type Facility
Cable Size
Proposed Crossing
Gauge
Strand
Maximum Voltage
Tracks of
R.R.
DC
Feet
Maximum Amps
In
Encasement Material
At or Near
Outside Diameter
Wall Thickness
of MP
County
Project Name
Project Number
Prepared By
NOTE:
© 2007 BICSI®
Indicate date of approval for an existing crossing.
8-49
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Sample Letter of Request for Railroad Permit
<Name of Railroad Superintendent>
<Name of Railroad>
<Address>
<City, State Zip>
Dear <Name of Superintendent>:
<Name of client> hereby applies for permission to construct a telephone plant crossing at
<location-distance in meters (feet) to nearest milepost> near <city and state>. The facility
being placed at this location <will or will not> serve a patron of your company exclusively and
<will or will not> be located within the limits of a public road.
The review of this proposed crossing and your prompt approval will be appreciated.
Yours truly,
<Your name and company>
Attachment
OSP Design Reference Manual, 4th edition
8-50
© 2007 BICSI®
Chapter 8: Right-of-Way
Underground Casings under Railroads
The casing pipe and joints shall be uniformly thick steel construction approved by the railroad’s
chief engineer and shall be capable in its entirety of withstanding load of railroad roadbed,
track and traffic; also shall be constructed so as to prevent leakage of any matter from the
casing or conduits contained therein throughout its length under track and railroad R/W. The
casing pipe may contain as few as three 100 mm (4 trade size) conduits or as many as thirtysix 100 mm (4 trade size) conduits. The different arrangements for different casing sizes are
shown in Figure 8.16.
The casing pipe must be installed with even bearing throughout its length, and to prevent
formation of standing liquids shall slope to one end. Wall thickness of the casing must be no
less than that specified in the attached steel casing pipe wall thickness chart (Table 8.1). The
inside diameter of the casing shall be at least 10 percent larger than the outside diameter of
the largest conduit contained in the casing but no less than 51 mm (2 in) greater than largest
outside diameter of conduit, joints or couplings.
The depth from base of railroad rail to top of casing at its closest point shall not be less than
1.4 m (4.5 ft) and on other portions of railroad R/W, and from bottom of ditches to top of
casing, shall not be less than 0.91 m (3 ft). Where it is not possible to secure the above depths,
special construction shall be used as approved by the railroad’s chief engineer.
The casing pipe shall extend at least 13.7 m (45 ft) or 2 (D) plus 6 m (20 ft), (where “D”
equals depth of the bottom of the casing below railroad subgrade), whichever is greater, each
side from (measured at right angles to) centerline of outside track. The casing is to extend
beyond the limit of the railroad R/W as required to obtain the specified length of additional
tracks are constructed in the future, the casing shall be correspondingly extended at the
applicant’s expense.
Casings are installed by the jack and bore method. This involves the excavation of jacking and
receiving pits on opposite sides of the crossing. Jacking/receiving pits shall be a minimum of
9 m (30 ft) from the centerline of track.
Casings can be installed at a 30 degree angle to the track up to a perpendicular angle of
90 degree (Figure 8.14). A typical engineering sketch indicating a proposed crossing is shown
in Figure 8.15. The information shown on this figure is the minimum information required.
Some railroad companies require additional information on the engineering drawings. Consult
with the railroad engineering office for any additional requirement prior to submitting an
application.
Upon completion of the casing installation work, all trash, excess materials, temporary
structure and equipment are to be removed and the railroad’s R/W cleaned and restored to the
satisfaction of the railroad’s chief engineer or authorized representative. Disturbed areas shall
be seeded or otherwise protected to control erosion as specified by the chief engineer of the
railroad.
© 2007 BICSI®
8-51
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Underground Casings under Railroads, continued
Figure 8.16
Arrangements for different casing sizes
Figure 5
508 mm (20 in) OD
490.52 mm (19.312 in) ID
Figure 1
305 mm (12 in) ID
3 Duct
Figure 2
356 mm (14 in) OD
399.75 mm (13.376 in) ID
10 Duct
Figure 6
559 mm (22 in) OD
539.75 mm (21.25 in) ID
4 Duct
Figure 3
406 mm (16 in) OD
390.55 mm (15.376 in) ID
14 Duct
Figure 7
610 mm (24 in) OD
587.35 mm (21.125 in) ID
7 Duct
Figure 4
457 mm (18 in) OD
439.72 mm (17.312 in) ID
16 Duct
Scale: Not to scale (relative scale)
B Duct
OSP Design Reference Manual, 4th edition
8-52
© 2007 BICSI®
Chapter 8: Right-of-Way
Underground Casings under Railroads, continued
Figure 8.16
Arrangements for different casing sizes, continued
Figure 8
660 mm (26 in) OD
3150 mm (124 in) ID
Figure 11
813 mm (32 in) OD
787.35 mm (30.998 in) ID
19 Duct
Figure 9
711 mm (28 in) OD
687.37 mm (27.062 in) ID
29 Duct
Figure 12
864 mm (34 in) OD
836.577 mm (32.94 in) ID
19 Duct
Figure 10
762 mm (30 in) OD
738.17 mm (29.062 in) ID
36 Duct
Scale: Not to scale (relative scale)
26 Duct
ID
in
mm
OD
© 2007 BICSI®
=
=
=
=
Inside Diameter
Inch
Millimeter
Outside Diameter
8-53
OSP Design Reference Manual, 4th edition
Chapter 8: Right-of-Way
Underground Casings under Railroads, continued
Table 8.1
Specifications for steel casing
Wall Thickness
*
**
ID
in
mm
OD
Inside Diameter
Diameter
mm (in)
Protected
in
*305 mm (12 in) ID
0.188
*356 mm (14 in) OD
0.219
*406 mm (16 in) OD
Nonprotected
in
Protected
in
Nonprotected
in
12
12
0.312
13.562
13.376
0.219
0.312
15.562
15.376
*457 mm (18 in) OD
0.250
0.344
17.500
17.312
*508 mm (20 in) OD
0.281
0.344
19.438
19.312
559 mm (22 in) OD
0.312
0.375
21.376
21.250
*610 mm (24 in) OD
0.344
0.438
23.312
23.124
660 mm (26 in) OD
0.375
0.438
25.250
25.124
711 mm (28 in) OD
0.406
0.469
27.188
27.062
*762 mm (30 in) OD
0.406
0.469
29.188
29.062
813 mm (32 in) OD
0.438
0.500
31.124
31.000
864 mm (34 in) OD
0.469
0.500**
33.000
*914 mm (36 in) OD
0.469
0.500**
35.000
965 mm (38 in) OD
0.500
0.500**
37.000
1016 mm (40 in) OD
0.500
0.500**
39.000
*1067 mm (42 in) OD
0.500
0.500**
41.000
*1220 mm (48 in) OD
0.500
0.500**
47.000
Stock sizes of casing. Other sizes available on special order only and will cost more than
larger stocked size.
These sizes require nominal wall thickness and coating.
= Inside diameter
= Inch
= Millimeter
= Outside diameter
OSP Design Reference Manual, 4th edition
8-54
© 2007 BICSI®
Chapter 9
Scope of Work
Chapter 9 defines scope of work and statement of work
and describes their differences and specific elements. It
discusses title, general statement, objective, specific tasks,
reporting requirements, qualification requirements, place
and period of performance, construction management,
restrictions, security clearance requirements, contracting
representatives, and attachments.
Chapter 9: Scope of Work
Table of Contents
Statement of Work ............................................................................. 9-1
Introduction ................................................................................................ 9-1
Title .......................................................................................................... 9-1
General Statement ....................................................................................... 9-1
Objective (Narrative) .................................................................................... 9-1
Specific Tasks ............................................................................................. 9-2
Type of Pathway .................................................................................... 9-2
Type of Cables ....................................................................................... 9-2
Splicing/Termination Requirements ............................................................. 9-2
Associated Hardware and Material Required ................................................. 9-2
Grounding Requirements ........................................................................... 9-3
Permit Requirements ................................................................................ 9-3
Code and Standard Requirements .............................................................. 9-3
Type of Restoration Required .................................................................... 9-3
Testing Requirements .............................................................................. 9-3
Documentation Requirements .................................................................... 9-3
Reporting Requirements ............................................................................ 9-4
Qualification Requirements ........................................................................ 9-4
Place and Period of Performance .................................................................... 9-4
Construction Management ............................................................................. 9-4
Restrictions ................................................................................................. 9-5
Security Clearances ..................................................................................... 9-5
Contracting Representative ........................................................................... 9-5
Attachments ............................................................................................... 9-5
Assumptions ................................................................................................ 9-5
© 2007 BICSI®
9-i
OSP Design Reference Manual, 4th edition
Chapter 9: Scope of Work
OSP Design Reference Manual, 4th edition
9-ii
© 2007 BICSI®
Chapter 9: Scope of Work
Statement of Work
Introduction
A statement of work is a document developed by either a client or a client/designer
collaborative team for defining the project requirements. A well-defined statement of work is
very important for a successful project. The critical elements of a statement of work include:
•
Title.
•
General statement.
•
Objective.
•
Specific tasks.
•
Reporting requirements.
•
Qualification requirements.
•
Place and period of performance.
•
Construction management.
•
Restrictions.
•
Security clearance requirements.
•
Contracting representative.
•
Attachments.
•
Assumptions.
This chapter outlines the major elements of a well-defined statement of work.
Title
The title can be very important if an organization has multiple solicitations each year. Some
procurement agencies choose to assign a number to each solicitation with the year embedded
in the number to help with identification (e.g., 0012007).
General Statement
The general statement is a brief description of the overall project.
Example of a general statement: “Furnish, install, and test a singlemode optical fiber cable
from building 01 to building 02.”
General statements lengthen and become more comprehensive as the size and scope of the
project increases.
Objective (Narrative)
The objective is a description of the overall project.
Example of an objective statement: “The new 12-strand optical fiber cable will provide
connectivity from the lab to the hospital so the doctors can read the x-rays without having
to walk to the lab.”
© 2007 BICSI®
9-1
OSP Design Reference Manual, 4th edition
Chapter 9: Scope of Work
Specific Tasks
The specific tasks identify each task that should be completed under this statement of work.
Some examples of important details that should be captured in the specific tasks section of the
statement of work are discussed below.
Type of Pathway
The designer should identify whether the outside plant (OSP) pathway will be aerial, direct
buried, underground, tunnel, or a combination. Some considerations for OSP pathways include:
•
Type, size, and quantity of poles required.
•
Type, size, and quantity of strand required.
•
Depth and width of trench.
•
Warning tape requirements.
•
Type, size, and quantity of maintenance holes (MHs) required.
•
Tunnel entrance and exit location.
NOTE:
It is recommended to include a schematic of the MH.
Type of Cables
The designer should identify the type and size of cables that need to be installed and specify
the length of the cables, including slack, if known.
Splicing/Termination Requirements
The designer should identify the type of termination methodology to be used for copper, optical
fiber, and coaxial cables. Some examples include:
•
Modular copper splicing.
•
Single-pair copper splicing.
•
Fusion optical fiber splicing.
•
Mechanical optical fiber splicing.
•
Optical fiber termination method.
Associated Hardware and Material Required
Associated hardware includes cabling hardware, closures, pathways, and connecting
hardware. Details for associated hardware should be listed in the material lists. Any special
requirements for these items may be included in the descriptions.
OSP Design Reference Manual, 4th edition
9-2
© 2007 BICSI®
Chapter 9: Scope of Work
Specific Tasks, continued
Grounding Requirements
The designer should identify any special grounding requirements. Some systems have specific
resistance level requirements.
Permit Requirements
The designer should identify any special types of permits that need to be obtained before
starting the project. Depending on the jurisdiction, some permits can take a substantial amount
of time to process.
Code and Standard Requirements
The designer should identify the codes and standards to which the project must conform.
Type of Restoration Required
The designer should identify what type of restoration is required. Some examples of
restoration include:
•
Sod and hydroseeding.
•
Concrete.
•
Asphalt.
•
Landscape.
Testing Requirements
The designer should identify what type of testing will be required. Some examples of testing
are:
•
Fiber test.
•
Copper test.
Documentation Requirements
The designer should identify what types of deliverables are required before, during, and after
project completion. Some examples of deliverables are the:
© 2007 BICSI®
•
Safety plan.
•
Test plan (before project start).
•
Final design (before project start).
•
List of materials (before project start).
•
Proof of concept (during project).
•
Test results (post project).
9-3
OSP Design Reference Manual, 4th edition
Chapter 9: Scope of Work
Specific Tasks, continued
•
Hard and soft copies of test results.
•
Drawings (post project).
•
D-sized computer-aided design (CAD) drawings.
•
Soft copy of CAD drawings.
Reporting Requirements
The designer should identify what deliverables are due to the customer during the course of
the project. Some examples include:
•
Progress reports.
•
Audits.
•
Safety reports.
Qualification Requirements
The designer should identify any special licenses, degrees, registrations, or special certifications that potential bidders must have as a minimum requirement for bidding on a project.
Examples of licenses, degrees, or special certifications include:
•
Master electricians licenses.
•
Professional engineer (PE).
•
Registered Communications Distribution Designer (RCDD®)/OSP Specialist.
•
BICSI Registered Information Transport Systems (ITS) Technician.
•
Senior right-of-way agent (SR/WA).
•
OSP project manager (PM).
Place and Period of Performance
The place of performance indicates the locations where the work will be performed. This also
is indicated on the construction work prints in the form of work location numbers. The period
of performance indicates both the first day and the final day of the contract. Additionally, the
hours of operation during which the work can be completed by the contractor are identified.
This also should be included in the project management documents (e.g., network diagram,
program evaluation review technique [PERT] and critical path method [CPM] charts).
Construction Management
The designer should determine whether an on-site construction manager (CM) is required for
the project. The designer should indicate whether there are any special or minimum
requirements for the CM (e.g., 10 years of experience, managing projects over $5 million,
RCDD/OSP Specialist).
OSP Design Reference Manual, 4th edition
9-4
© 2007 BICSI®
Chapter 9: Scope of Work
Restrictions
The designer should identify any special restrictions that might be relevant to the job. Some
examples include:
•
Schedule.
•
Environmental.
•
Prevailing wages/Davis Bacon wages.
•
Governmental restrictions.
Security Clearances
Some government and commercial work may require a variety of security clearances. The
designer should identify the scope of the security for the project and delineate in the project
plan how the requirements will be handled.
Contracting Representative
The designer should identify who will be the customer’s authorized representative to make
contractual decisions for the project. The name, office or agency, address, telephone and fax
number, and e-mail address of the customer’s representative should be included.
Attachments
The designer should list any attachments that are included in the statement of work. Some
examples are the:
•
Schedule.
•
Wage determinations.
•
Construction drawings for pathways, spaces, media, and termination and splicing
hardware for the buildings,
•
Bonding and grounding drawings for OSP and entrance facilities (EFs).
•
Conceptual drawings.
•
Test procedures for all media installed and terminated/spliced.
•
System requirements documentation.
Assumptions
The designer should include any project-specific assumptions that are required.
© 2007 BICSI®
9-5
OSP Design Reference Manual, 4th edition
Chapter 10
Design Documentation
Chapter 10 explains the task of developing construction
documents by phases—schematic design, construction
documents, work prints, and as-built—and provides
outside plant (OSP) design and specification checklists.
Chapter 10: Design Documentation
Table of Contents
Construction Documents ................................................................... 10-1
Introduction .............................................................................................. 10-1
Schematic Design ...................................................................................... 10-2
Cable Assignment .................................................................................. 10-3
Feeder Sizing ....................................................................................... 10-3
Distribution Sizing ................................................................................. 10-4
Projection Planning ................................................................................ 10-4
Fiber to the X (FTTx) ............................................................................ 10-5
Counts and Assignments ........................................................................ 10-5
Construction Documents ............................................................................. 10-6
Outside Plant (OSP) Design and Construction Checklist .................... 10-9
Introduction .............................................................................................. 10-9
Outside Plant (OSP) Design Checklist ............................................................ 10-9
Title Block (Reference No. 1) ................................................................ 10-11
Required Information (Reference No. 2) .................................................. 10-12
Electronic Telecommunications Equipment (Reference No. 3) ...................... 10-13
Notes (Reference No. 4) ...................................................................... 10-13
Aerial Environment (Reference No. 5) ..................................................... 10-13
Direct-Buried Environment (Reference No. 6) ........................................... 10-14
Conduit Environment (Reference No. 7) .................................................. 10-14
Underground Environment (Reference No. 8) ........................................... 10-14
Miscellaneous (Reference No. 9) ............................................................ 10-15
Outside Plant (OSP) Construction Specifications Checklist .............................. 10-16
General (Reference No. 1) .................................................................... 10-18
Title Block (Reference No. 2) ................................................................ 10-19
Safety Requirements (Reference No. 3) .................................................. 10-19
Notes (Reference No. 4) ...................................................................... 10-20
Cable and Stubs (Reference No. 5) ........................................................ 10-20
Cable Terminals (Reference No. 6) ......................................................... 10-21
Poles (Reference No. 7) ....................................................................... 10-21
Load Coils (Reference No. 8) ................................................................. 10-21
Maintenance Holes (MHs [Reference No. 9]) ............................................ 10-22
Conduit (Reference No. 10) .................................................................. 10-22
Removals (Reference No. 11) ................................................................ 10-22
Work Print Information Examples—Metallic Cables .......................................... 10-23
© 2007 BICSI®
10-i
OSP Design Reference Manual, 4th edition
Chapter 10: Design Documentation
Figures
Figure 10.1
Splicing together two sections of same cable .............................. 10-23
Figure 10.2
Splicing a shorted cable order ................................................... 10-23
Figure 10.3
Splicing two cables of different sizes .......................................... 10-24
Figure 10.4
Splicing a new branch cable to a feed cable ................................ 10-24
Figure 10.5
New cables and a terminal spliced .............................................. 10-25
Figure 10.6
Cross-connect cabinet terminating gel-filled cables ...................... 10-25
Figure 10.7
Removal of NF-16 terminal ........................................................ 10-26
Figure 10.8
Replacing an NF-16 terminal with an NF-25 terminal ...................... 10-26
Figure 10.9
Energizing dead pairs ............................................................... 10-27
Figure 10.10
Remove cross-connect terminal ................................................. 10-27
Figure 10.11
200-Pair cable transfer at splice ................................................ 10-28
Figure 10.12
300-Pair cable transfer to new feeder cable ................................ 10-28
Figure 10.13
Section replacement on 300-pair cable ....................................... 10-29
Figure 10.14
Protector placement ................................................................ 10-29
Figure 10.15
Sample maintenance hole plan and profile drawing ........................ 10-30
Figure 10.16
Butterfly detail worksheet ......................................................... 10-31
Figure 10.17
Butterfly detail ........................................................................ 10-32
Tables
Table 10.1
Construction document specifications process ............................... 10-8
Table 10.2
Outside plant design checklist ................................................... 10-10
Table 10.3
Outside plant construction specifications checklist ....................... 10-17
OSP Design Reference Manual, 4th edition
10-ii
© 2007 BICSI®
Chapter 10: Design Documentation
Construction Documents
Introduction
Design documentation is an important set of deliverables in an outside plant (OSP) project.
These documents are used when building OSP. They should be readable and detailed, using
legends and lists of symbols. Technicians and contractors must follow the documents
produced by the information transport systems (ITS) distribution designer. In cases where the
documents or intent of the work is questionable, the designer must be consulted.
The task of developing design documents begins early in the design process. The final work
prints or construction drawings represent a compilation of all of the data that has been
recorded by the designer of existing OSP conditions as well as all of the proposed facilities.
This data is detailed in drawings under each of the following steps:
© 2007 BICSI®
•
Schematic design—At this stage, the designer uses the notes acquired during the field
survey to design the proposed OSP facilities. The designer may work directly on the field
notes or may choose to have drafting personnel develop preliminary work prints, which
would then be used by the designer to plot the proposed OSP facilities.
•
Construction documents—The final design drawings (work prints) and specifications that
will be issued to the construction forces for the placement of proposed OSP facilities.
•
Work prints—The drawings used by the construction team to install the OSP facilities to
document any changes made during construction. These changes are incorporated into the
computer-aided design (CAD) drawings to complete the set of as-built prints, which are
returned to the designer and customer.
•
As-built—The final set of drawings produced by the construction team to note changes
built in the field and to document major obstructions encountered during the building
process.
10-1
OSP Design Reference Manual, 4th edition
Chapter 10: Design Documentation
Schematic Design
Work prints are developed to determine future cable requirements. They may include the
number of balanced twisted-pairs, optical fiber strands, coaxial, or other cable requirements.
These requirements can only be forecast after considering requirements for existing business
and the anticipated use of vacant property. This information may be obtained through review
of the owner’s long-range plans or campus master plan. Other sources include population
forecasts, interviews with developers and planning departments, and the site survey.
Once this information is collected, the forecast requirements must be analyzed to identify
immediate or future shortages and multiple conditions found with balanced twisted-pair, optical
fiber, or coaxial cabling. This information should also be included on work prints to formulate a
plan for expansion.
Once the work print is marked with this forecasted information, the designer determines:
•
Which distribution cables need immediate and future expansion.
•
Where new distribution cables will be needed.
•
Immediate or future rearrangements necessary for balanced twisted-pair, coaxial, and
optical fiber distribution cables and terminals.
•
Where main feeder cable expansion is needed.
•
How many immediate and future cables will be needed, including balanced twisted-pairs
or optical strands.
•
The most cost-effective technology that will accomplish the job.
When designing feeder and distribution cables in either new or rearranged OSP, the designer
must ensure that the distribution cables provide a sufficient number of cable pairs, optical fiber
strands, and coaxial cabling for the ultimate needs of the business or the area to be served.
Balanced twisted-pair cables should be free from multiple appearances, not bridged, and
should be administered in groups of 25 sequential pairs (e.g., binder groups).
Optical fiber cables should be administered by cable construction.
The success of any design depends on in-depth planning and applying the fundamental
principles of OSP design. Data gathering is the most important aspect of design. The designer
should first obtain copies of the latest cable assignment records. If existing work prints are
available, the designer should determine the number of working balanced twisted-pairs or
optical strands in the cable sections and post the information at locations where the cable
sections taper. This will provide a good depiction of the cabling layout and the number of
working pairs or strands.
OSP Design Reference Manual, 4th edition
10-2
© 2007 BICSI®
Chapter 10: Design Documentation
Schematic Design, continued
Cable Assignment
The basic concept in OSP is similar to exchange area cabling for central offices (COs) and
can be described as two general components:
•
Feeder cables, which come from the campus main cross-connect (MC [campus
distributor (CD)]) and extend to the last branch cable splice or cross-connect point.
Feeder cables are typically spliced to smaller distribution or branch cables that terminate
within a building.
•
Distribution cables, which extend from a cross-connect terminal or optical fiber patch
panel or branch off a feeder cable through splicing.
Feeder cables are planned and installed to provide coverage for a particular area or a specific
route. Distribution cables are designed to provide service to specific discrete areas within that
feeder’s coverage area or route.
Another term that may be applied collectively to both feeder and distribution cables in OSP is
backbone cabling. Such cabling is often called campus backbone or OSP backbone. OSP
cabling in campus environments also has been termed trunk cable, although, in exchange
terminology, a trunk is a circuit or path between two switches, at least one of which is a
telephone CO or switching center. Regular CO circuits or services are called private branch
exchange (PBX) trunks because there is a switch at both ends of the circuit. Proper
terminology for trunk cabling, therefore, is cable placed between two switching centers.
However, the term trunk cable has been applied in campus design to general OSP cabling.
The term trunk also is used in the optical fiber network to link synchronous optical network
(SONET), switched services, voice over Internet protocol (VoIP), data equipment nodes, and
internetworking devices.
Feeder Sizing
The next determination is cable sizing. The first part is the size of the feeder cable. Feeder
pair or strand count is based on the:
© 2007 BICSI®
•
Number of balanced twisted-pairs required for initial use. This includes dry copper
telephone pairs, special service requirements (e.g., data, fire alarm, and security), and any
immediate changes in present services.
•
Feeder balanced twisted-pair cable count. The count is generally increased to provide a
pair-for-pair match with all of the expected distribution cables.
•
Number of optical fiber strands required for initial use. This includes the number of
SONET, Ethernet, VoIP, switched, or point-to-point (PTP) services. SONET, Ethernet,
VoIP, and switched networks typically use two strands, in and out of a CO or a building
being served. A PTP service, such as telephony or Ethernet extensions and video links,
uses two strands. Other video links and networks use a single strand.
10-3
OSP Design Reference Manual, 4th edition
Chapter 10: Design Documentation
Schematic Design, continued
•
Rate of growth of the designated area. This information helps to discern the types and the
quantity of service needed in the foreseeable future. The forecast should be planned for
the longest timeframe possible, perhaps 20 or more years. However, forecasting at least
10 years in the future is recommended.
•
Use of a campus master plan, if one is available.
Distribution Sizing
The next step is planning the distribution portion of the cable plant. In initial cable placement
for a coverage area, the distribution portion of the total cable plant had had more balanced
twisted-pair or optical strand counts than the feeder serving the area. To terminate all of the
distribution cable pairs, the practice of stubbing balanced twisted feeder pairs and/or bridging
feeder pairs had been used. Today, those practices are no longer followed or acceptable when
using today’s technologies.
The evolution of design standards led to the placement of the ultimate size distribution cable in
the area, especially when buried to meet legislative requirements or for esthetic concerns.
Living units were assigned one and one-half to three or more distribution balanced twistedpairs in anticipation of additional line growth for faxes, computers, alarm systems, and
communications.
The recommendation for optical strands to a building for service is typically 6 to 24 strands per
building in anticipation of building into additional buildings for communications, data, or video
networks along the distribution cable. Due to SONET, Ethernet, and other communications
equipment working in a ring configuration, the same strands can be assigned to a number of
buildings for distribution cable sizing. It is important to know the number of allowable nodes a
certain equipment application can have.
Projection Planning
Typically, feeder cable size planning is based on a comparison of the cost of reinforcing a
route and the cost of investing in idle capacity until some future date and also consideration of
technological advances that may emerge during the period. The future date is determined by
the area’s growth rate and the provided facilities’ consumption.
Since the planning is on a multi-year basis, the plans should be periodically reviewed to ensure
that the underlying assumptions are still valid. Some planners establish a specific horizon for
their planning cycle (e.g., a five-year projection or sales projections by the sales staff).
Following are some application-specific examples:
•
In aerial plant, additional cable can be overbuilt onto the support strand of the initial cable
or sufficient clearance can be provided for additional cable placement on the pole line.
This is based on load calculations.
•
In underground plant, additional cable can be placed in spare conduit or innerducts within
the duct bank route.
OSP Design Reference Manual, 4th edition
10-4
© 2007 BICSI®
Chapter 10: Design Documentation
Schematic Design, continued
•
Direct-buried plant requires oversizing the feeder because of the challenges imposed by
revisiting the route and adding additional capacity at a later date. Therefore, for directburied plant, cables should be sized to provide for at least 20 years.
•
When designing for campus area distribution, a prospective growth pattern (e.g., five
years, 10 years, or longer) should be assumed, if such projections are reasonable, and pair
or strand count should be planned accordingly. The designer can use the information
gathered from the site master plan to determine the projections.
Fiber to the X (FTTx)
Planning for an FTTx installation will follow many of the same criteria as for balanced
twisted-pair and fiber installations with additional considerations for the following:
•
Locations and number of optical line terminals (OLTs) serving the fiber plant
•
Locations and number of splitters required
•
Locations and number of optical network terminals (ONTs) being served by the fiber plant
Counts and Assignments
Provide sufficient pair and strand count plus a percentage of growth rounded up to the next
full cable size for the feeder’s service area. The method of providing sufficient pair or strand
count is to factor in one-half pair for every two pair required; then add the growth factor.
Growth factor is typically 15 to 20 percent depending on projections. The less certain the
projection, the higher the growth factor needs to be.
When assigning pair or strand counts from the main feeder cables through to the distribution
or lateral cables, try to avoid leaving pairs or strands unassigned “cut dead” in a splice, unless
the growth factor calculations dictate that additional cables will be installed within the growth
factor projections. Only allow balanced twisted-pair binder or strand bundle groups cut,
cleared, and capped in the splice if there is near-term future building placement and
anticipated service requirements. Otherwise, provide pair-for-pair or strand-for-strand full pair
counts from the feeder cable to the distribution cables.
Typically, the main or feeder cable originating at the campus MC (CD) should be assigned and
spliced out to the distribution cables serving the remote facilities using the following rules:
© 2007 BICSI®
•
Never break up balanced-twisted pair binder or optical bundle groups. Always assign full
binders or bundles to all remote locations.
•
Use the tree concept. Assign the first balanced twisted-pair binders in the center of the
feed cable to the farthest distribution points away from the campus MC (CD). Assign the
next binders out from the center of the sheath back toward the campus main feed point.
Therefore, the pairs in the center of the feed cable are the “tallest” (or longest) and the
pairs outward from the center are progressively shorter, giving the cable plant the image
of a tree.
10-5
OSP Design Reference Manual, 4th edition
Chapter 10: Design Documentation
Schematic Design, continued
•
Place splices and terminations at logical junctures in the overall plant. Ensure that there is
security at the point of connection so that unauthorized individuals cannot cause harm but
also that craftspeople can work on the administration point. This will differ in planning
depending on the cable route construction.
•
The same techniques can be used for optical fiber cable applications. The previous bullets
one and three also apply to optical fiber construction. Assign the bundle groups with the
lowest strand counts to the farthest distribution point back toward the main feed point.
Construction Documents
After the site survey and schematic designs have been completed, the designer has the
necessary proposed information for plotting the final information onto a set of drawings. These
drawings will be issued to the construction crew for the placement of the proposed OSP
facilities. Table 10.1 describes the construction document process.
The size of the work print medium should be large enough to be read and small enough to be
easily handled by construction personnel in the field. Typically, 11 x 17 in drawings are the
easiest to handle in the field. However, it is not uncommon to use a larger document produced
on a plotter when a larger picture of a construction project is required.
Black-and-white documents are also easier to read in the field and are generally preferred.
Some companies use blue colored lines for aerial plant construction and green colored lines for
buried plant construction. Multiple sets are usually distributed for bidding, construction, or
reference purposes. Distribution lists should be compiled to track the routing of initial and
revised issues. A routing cover (i.e., transmittal) sheet should accompany the set of drawings
and specifications. Drawings are dated and the author is identified to track revisions.
Final work prints must follow the OSP design and construction checklists (see Tables 10.2 and
10.3) for all applicable items. Construction document prints should be checked and approved
before issuing. These prints will become a final as-built upon completion. Approved and dated
revisions must be plotted and reissued when required.
Once all work is completed and the job is tested and accepted, the as-built prints become a
final record that must be maintained for reference.
OSP Design Reference Manual, 4th edition
10-6
© 2007 BICSI®
Chapter 10: Design Documentation
Construction Documents, continued
The project specifications should follow the latest Construction Specifications Institute (CSI)
MasterFormat™. Each specification section is broken into three parts:
•
Part 1—General information such as related documents and specification sections,
summary of work, and submittals and references required
•
Part 2—Materials to be used
•
Part 3—Direction on project execution
CSI MasterFormat numbers and titles are suitable for use in project manuals for organizing
cost data, drawing key notes, filing project technical data, and identifying drawing objects.
The latest change in the MasterFormat was adopting a six-digit numbering system. For
example, 27 13 00 is for communications backbone cabling: 27 is the division number or level 1
and 13 and 00 are level 2 and 3 assignments, respectively.
The most common divisions for the designer are:
•
27—Communications.
•
31—Earthwork.
•
33—Utilities.
Some companies do not recognize the CSI MasterFormat. However, these same three parts
must be adhered to when producing a specification or drawings for construction.
© 2007 BICSI®
10-7
OSP Design Reference Manual, 4th edition
Chapter 10: Design Documentation
Construction Documents, continued
Table 10.1
Construction document specifications process
Site Survey
•
•
•
•
•
•
•
•
Obtain property owner and or building management permission.
Verify security requirements.
Identify special permits required.
Determine proposed route infrastructure.
Determine location(s) of signal repeater or regeneration sites, optical line terminals (OLT),
or passive optical network (PON) splitters, if required.
Indicate possible splice locations.
Determine property and public owned facilities.
Determine the entrance required to enter a building.
Field Survey
•
•
•
•
Make video or digital photos of field conditions.
Obtain prints from other agencies for future plans.
Survey existing maps or records.
Survey and document detailed requirements.
Schematic Design
•
•
•
•
•
Future cable and pair or strand requirements are forecasted.
Cable assignments are applied.
Feeder or distribution are sized.
Projection plan is posted.
Cable pair or strand counts are distributed and assigned.
Construction Documents
See specific checklists (Table 10.2 and Table 10.3).
OSP Design Reference Manual, 4th edition
10-8
© 2007 BICSI®
Chapter 10: Design Documentation
Outside Plant (OSP) Design and Construction Checklist
Introduction
In the design and construction of telecommunications facilities, documentation, evaluations,
research, and identification of information are required to successfully build an OSP facility.
An accepted method for organizing this information is with the use of checklists.
Checklists are used to generate a thought process about various questions that need to be
answered regarding any project. Checklist contents (i.e., types of questions and issues) vary
throughout the world and within the many different companies involved in this type of work.
The following is an explanation of the OSP design and construction checklist.
Outside Plant (OSP) Design Checklist
A checklist is an aid to the designer. This checklist assists the designer in considering all of the
information that may be pertinent to the OSP project. A checklist contains multiple categories
with many sublistings of line items that may need to be considered. It also provides additional
information for interdepartmental requirements (e.g., accounting, operations).
Typically, a designer reviews all of the line items on the entire checklist. If a line item is
pertinent to the project or the information has value to other departments or personnel involved
with the project, that particular information is included or considered during the project’s
design phase.
Table 10.2 is a representative example of the quantity or type of information that a designer
has to consider for inclusion with the project. A checklist may be modified to suit the needs of
a particular design office or for local campus environments.
© 2007 BICSI®
10-9
OSP Design Reference Manual, 4th edition
Chapter 10: Design Documentation
Outside Plant (OSP) Design Checklist, continued
Table 10.2
Outside plant design checklist
3
Reference
Number
Title and
Subtitles
Title Block
Reference number
Service date
Geographic location
Exchange/campus site
Issue date
Municipality
County
Township
Section
Location and description
Street names
Initials of drafter
Initials of designer
Designer telephone number
Plant locator record (PLR)
number
North arrow
Accounting data
‰
‰
‰
‰
4.
4.1
4.2
4.3
Notes
Assignment
Construction
Method of procedure
‰
‰
‰
‰
‰
‰
‰
5.
5.1
5.2
5.3
5.4
5.5
5.6
Aerial Environment
Anchor/guy
Lash/strand/self-support
Pole information
Span measurements
Pole load calculations
Expansion loops
‰
‰
‰
6.
6.1
6.2
‰
‰
6.3
6.4
Direct-Buried Environment
Direct-buried/direct-buried jobs
Pedestal or splice vault
information
Station marker/components
Underground (UG) utilities
identified
Required Information
Cable ID and count
Telecommunications equipment
room direction
Streets (at least two)
Loop and count qualification
Facilities lifecycle
Regroup
Splice to splice measurements
Terminals involved
Balanced twisted-pair wiring limits
Permits and right-of-way (R/W)
Fill boxes
Conductor/transmission study
‰
‰
‰
‰
‰
‰
7.
7.1
7.2
7.3
7.4
7.5
Conduit Environment
Conduit description
Conduit configuration
Innerduct description
Tie-in measurements
Wall-to-wall measurements
‰
‰
‰
‰
‰
‰
‰
8.
8.1
8.2
8.3
8.4
8.5
8.6
Underground Environment
Air pressure information
Buffer information
Conduit selection
Cable type information
Optical fiber cable selections
Maintenance hole numbers
‰
‰
9.
9.1
‰
‰
‰
9.2
9.3
9.4
‰
‰
9.5
9.6
Miscellaneous
Grounding (earthing) and bonding
information
Caution information
Transfer splicing
Balanced twisted-pair crossconnect box information
Lightning protection
Optical fiber patch panel
3
Reference
Number
Title and
Subtitles
‰
‰
‰
‰
‰
‰
‰
‰
‰
‰
‰
‰
‰
‰
‰
‰
1.
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
1.10
1.11
1.12
1.13
1.14
1.15
‰
‰
1.16
1.17
‰
‰
‰
2.
2.1
2.2
‰
‰
‰
‰
‰
‰
‰
‰
‰
‰
2.3
2.4
2.5
2.6
2.7
2.8
2.9
2.10
2.11
2.12
‰
3.
‰
‰
‰
3.1
3.2
3.3
Electronic Telecommunications
Equipment
Equipment information
Relay rack/bay
Remote terminal (RT), controlled
environmental vault (CEV)
information
OSP Design Reference Manual, 4th edition
10-10
© 2007 BICSI®
Chapter 10: Design Documentation
Outside Plant (OSP) Design Checklist, continued
Title Block (Reference No. 1)
Following are explanations of title block headings in the OSP design checklist:
© 2007 BICSI®
•
Reference number (1.1)—A means of identifying the current project; in case of projects
that may be designed or constructed sequentially or concurrently, this reference number is
a means of tracking the order of completion. Most reference numbers identify the year
and month of the project.
•
Service date (1.2)—The date that the physical placement of facilities, the splicing
operations, or the job cutover were completed, respectively, or the actual date when the
project will be ready to deliver service to the customer.
•
Geographic location (1.3)—Usually the approximate location of the project’s
telecommunications equipment room (ER) or physical site that is known and used as
reference.
•
Exchange/campus site (1.4)—Term that is used for customers who have multiple
exchange or campus sites; identifying the campus or exchange site reduces the chance of
confusion among multiple projects.
•
Issue date (1.5)—Date the document is issued.
•
Municipality (1.6)—Name of the municipality or other government entity where the
project is taking place, if applicable.
•
County (1.7)—Name of the county where the project is taking place, if applicable.
•
Township (1.8)—The township where the project is taking place, if applicable.
•
Section (1.9)—A section number of the township where the project is taking place, if
applicable.
•
Location and description (1.10).
•
Street names (1.11)—The space for a locator map for the job and a brief description of
what the job accomplishes.
•
Initials of drafter (1.12).
•
Initials of designer (1.13).
•
Designer telephone number (1.14).
•
Plant locator record (PLR) number (1.15)—Reference to the schematics for the work
project; necessary if modifications are required and the designer has to look at the current
plant records.
•
North arrow (1.16)—An important part of the drafting process that must be properly
shown on the field notes.
•
Accounting data (1.17)—Information needed for the owner to maintain records for capital
and expense information associated with the network.
10-11
OSP Design Reference Manual, 4th edition
Chapter 10: Design Documentation
Outside Plant (OSP) Design Checklist, continued
Required Information (Reference No. 2)
Following are explanations of required information headings in the OSP design checklist:
•
Cable identification (IP) number and count (2-11))—Pair/strand count or size of each
cable on the project (e.g., 06 cable, 1-400, .500AL) and sheath type
•
Telecommunications equipment room direction (2.2)—The direction showing the way
back to the MC (CD)
•
Streets (2.3)—At least two street crossings or land marks near the project
•
Loop and count qualification (2.4)—Any terminals, optical fiber patch panels, or looped
cables showing all cable pair or strand counts
•
Facilities lifecycle (2.5)—The current year, date, and month of cable placements for this
project
•
Regroup (2.6)—A regroup activity is defined as customers who are currently using the
cable that will be replaced or removed with the project and need to be regrouped or cut
onto new facilities so they will not lose service.
•
Splice to splice measurements (2.7)—All cable measurements between splices.
•
Terminals involved (2.8)—A list of all terminals or optical fiber panels that will be involved
in a cable throw or cable cut. (This aids the construction personnel in project cutover and
helps to eliminate potential for cutting a customer out of service.)
•
Balanced twisted-pair wiring limits (2.9)—Refers to the assignments of a particular
terminal. Typically, they will only assign a series of addresses within a specified limit
(e.g., 10183 Hawthorne Lane – 10197 Hawthorne Lane) to a specific terminal. (If a new
address falls outside those limits, a designer must go to the field and determine if a new
terminal is needed or if the wiring limits need to be modified.)
•
Permits and right-of-way (R/W) (2.10)—Permits involved with the project; municipalities,
railroad, or other entities.
•
Fill boxes (2.11)—The existing cable fill (number of working lines) on the cables that will
be affected by the project
•
Conductor/transmission study (2.12)—Identifies whether this project requires an
evaluation or transmission study to determine correct signaling and supervision of the
circuits. (In case of optical fiber cables, the cable length loss, splice loss, and termination
loss may require an evaluation.)
OSP Design Reference Manual, 4th edition
10-12
© 2007 BICSI®
Chapter 10: Design Documentation
Outside Plant (OSP) Design Checklist, continued
Electronic Telecommunications Equipment (Reference No. 3)
Following are explanations of electronic telecommunications equipment headings in the OSP
design checklist:
•
Equipment information (3.1)—All pertinent information (e.g., vendor, model number)
regarding the equipment to be installed with this project.
•
Relay rack/bay (3.2)—The exact frame, rack, bay, or plywood backboard in the
telecommunications room (TR) for the electronic equipment.
•
Remote terminal (RT) and controlled environment vault (CEV) information (3.3)—All
pertinent information regarding the placement of RTs or CEVs.
Notes (Reference No. 4)
Following are explanations of notes headings in the OSP design checklist:
•
Assignment (4.1)—Any pertinent notes to assignments that may assist with a smooth and
efficient cutover or activation of the newly installed OSP for the project.
•
Construction (4.2)—Any pertinent notes to construction that may assist with a smooth and
efficient placing and splicing in this project.
•
Method of procedure (4.3)—Specific step-by-step information to ease splicing, cutover, or
equipment node placement work requirements.
Aerial Environment (Reference No. 5)
Following are explanations of aerial environment headings in the OSP design checklist:
© 2007 BICSI®
•
Anchor/guy (5.1)—Information pertinent to the lead/height, angles of pole contact, and
size of anchor and guy.
•
Lash/strand/self-support (5.2)—Identifies whether the cable is to be lashed to the strand,
the size of the strand, or the cable is to be a self-supporting cable.
•
Pole information (5.3)—The class and height of any new poles and whether the existing
poles are sufficient to support the weight of the new facility and are in good condition.
•
Span measurements (5.4)—All span-to-span pole measurements.
•
Pole load calculation (5.5)—The calculated load capacity of the pole.
•
Expansion loops (5.6)—The frequency and size of coaxial cable expansion loops.
10-13
OSP Design Reference Manual, 4th edition
Chapter 10: Design Documentation
Outside Plant (OSP) Design Checklist, continued
Direct-Buried Environment (Reference No. 6)
Following are explanations of direct-buried environment headings in the OSP design checklist:
•
Direct-buried/direct-buried joint (6.1)—Identifies whether cable will be, for example,
direct-buried joint with power or community antenna television (CATV) or by itself.
•
Pedestal or splice vault information (6.2)—The types and sizes of pedestals or vaults used
for distribution/splicing.
•
Station marker/components (6.3)—The types of equipment used at the customer station
and what, if any, additional components will be associated with this installation.
•
Underground (UG) utilities identified 6.4)—Utilities that exist in the area that may affect
the installation (e.g., power, gas, CATV, municipal facilities).
Conduit Environment (Reference No. 7)
Following are explanations of conduit environment headings in the OSP design checklist:
•
Conduit description (7.1)—The size and type of conduit (polyvinyl chloride [PVC]/
Schedule 40/60/80, concrete, steel).
•
Conduit configuration (7.2)—The configuration necessary for this installation (e.g., 2 by 2,
2 by 3, 3 by 4). A profile of the conduit configuration is shown for proper water drainage.
•
Innerduct description (7.3)—The type of innerduct used in the system (e.g., corrugated,
smooth wall, fabric mesh); quantity and size of innerduct installed in each conduit; and
color-coding preferences.
•
Tie-in measurements (7.4)—Shows all tie-in measurements for the conduit run, including
all lateral ducts for both horizontal and vertical distances.
•
Wall-to-wall measurements (7.5)—Shows all wall-to-wall measurements between every
maintenance hole (MH) and wall-building measurements where entrance facilities (EFs)
are required.
Underground Environment (Reference No. 8)
Following are explanations of underground environment headings in the OSP design checklist:
•
Air pressure information (8.1)—Any air pressure systems involved with the project and a
description of how it will affect the work.
•
Buffer information (8.2)—Determines if a facility requires buffering, describes how to
buffer the cable and prevent activating air pressure alarms. (Proper buffering techniques
will also protect the cable from water damage).
OSP Design Reference Manual, 4th edition
10-14
© 2007 BICSI®
Chapter 10: Design Documentation
Outside Plant (OSP) Design Checklist, continued
•
Conduit selection (8.3)—Based on the most feasible and efficient route for placing and
splicing procedures The next placing project should always be considered when selecting
a conduit.
•
Cable type information (8.4)—Determines if gel-filled, gopher-proof, or nondielectric
cable will be required; whether the cable meets code requirements; and the environment
on the inside of the building entrance that the cable may pass through.
•
Optical fiber cable sections (8.5)—The optical fiber cable should have sufficient cable
ends to be spliced out of the MH and coil wrapped back into the hole (approximately
30.5 m [100 ft]) for future arrangements.
•
Maintenance hole numbers (8.6)—Each MH should be numbered in a sequential manner
and identified on the work prints.
Miscellaneous (Reference No. 9)
Following are explanations of miscellaneous headings in the OSP design checklist:
© 2007 BICSI®
•
Grounding (earthing) and bonding information (9.1)—Includes all appropriate grounding
(earthing) and bonding requirements for the project to ensure that the requirements meet
the code requirements.
•
Caution information (9.2)—Lists in bold letters any warnings or cautions that may affect
the safety of personnel on the project or that may damage the facilities.
•
Transfer splicing (9.3)—Any working balanced twisted-pair cable pairs or optical fiber
strands that will be transferred from one cable count to another through a cutover process
and the use of any sequence of work operations.
•
Balanced twisted-pair cross-connect box information (9.4)—Includes the type and style of
cross-box to be used and the lateral feed and distribution cables entering and leaving the
cross-box; the number of working lines and spare facilities in the box upon completion;
and any special placing or splicing configurations that may be necessary because of the
geography. The measurements should always be tied in with the cross-connect box
location and the nearest pole, pedestal, or roadway.
•
Lightning protection (9.5)—Identifies whether the balanced twisted-pair cable entering the
building meets the code requirements and the type of fused protection used (e.g., gas,
carbon, or solid state)
•
Optical fiber patch panel (9.6)—The type and size of optical fiber panel to use and the
cables entering the optical fiber panel and assigns an optical fiber strand count within the
panel. The working strands within the optical fiber panel should be labeled on its
assignment sheet.
10-15
OSP Design Reference Manual, 4th edition
Chapter 10: Design Documentation
Outside Plant (OSP) Construction Specifications Checklist
An OSP construction specifications checklist (see Table 10.3) is similar to the OSP design
checklist. A designer checks off the checklist items that are used to design the project. The
designer then determines with an OSP construction specifications checklist what information
is pertinent to construction personnel. This construction specifications checklist contains
common items with the design checklist but in many cases may not be required to be on the
construction work prints.
The required information placed on the construction work prints:
•
Assists construction in completing the work project in a timely manner.
•
Limits any unnecessary delays.
•
Reduces liabilities.
•
Increases safety.
•
Identifies and documents pertinent information.
OSP Design Reference Manual, 4th edition
10-16
© 2007 BICSI®
Chapter 10: Design Documentation
Outside Plant (OSP) Construction Specifications Checklist, continued
Table 10.3
Outside plant construction specifications checklist
3
Ref No.
Title and Subtitles
3
Ref No.
Title and Subtitles
‰
‰
‰
‰
‰
‰
‰
‰
‰
‰
‰
‰
‰
1.
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
1.10
1.11
1.12
‰
‰
‰
‰
‰
‰
‰
‰
‰
5.5
5.6
5.7
5.8
5.9
5.10
5.11
5.12
5.13
Markers
Obstructions
Conduit or pipe
Reel number
Measurements
Pressurization and buffering material
Fuse link
Final counts
Direct-buried drops
‰
‰
‰
6.
6.1
6.2
‰
1.13
‰
‰
‰
‰
1.14
1.15
1.16
1.17
General
City/county
Permits required
Service date/ship date
Million conductor feet (MCF)
Copies to
Service order information
Transmission information
Billing
North arrow
Joint-use caution note
Street names
Right-of-way (R/W) and easement
information
Distance to telecommunications
equipment room (ER)
Symbols
Existing plant
Joint trench bonding information
Special services
‰
‰
‰
6.3
6.4
6.5
Cable Terminals
Type/size/count
Protection/grounding (earthing )
information
Address/wiring limits
Backboard sketch
Terminal equipment/connecting blocks
‰
‰
‰
‰
‰
‰
2.
2.1
2.2
2.3
2.4
2.5
Title Block
Nature/necessity
Work order number
Voltage
Maintenance
Date and author
‰
‰
‰
‰
‰
‰
‰
‰
‰
7.
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
Poles
Size/class
Staking informaiton
Joint use
Lead/height
Span lengths
Caution notes
CATV/electric company request
Pole removal information
‰
‰
‰
‰
‰
‰
‰
‰
3.
3.1
3.2
3.3
3.4
3.5
3.6
3.7
Safety Requirements
Clearances/separations
Traffic lights
Other utilities
Special notes for work personnel
Pole condition
Direct-buried power
Safety requirements
‰
‰
‰
8.
8.1
8.2
Load Coils
Type case
Pair count
‰
‰
‰
‰
‰
‰
‰
‰
‰
4.
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
Notes
Existing facilities
Shield continuity/conformance
Cable acceptance
Building terminal sketch
Cutover drops
Contact owner
Sequence of splicing operations
Scheduling
‰
‰
‰
‰
‰
‰
‰
9.
9.1
9.2
9.3
9.4
9.5
9.6
Maintenance Holes (MHs)
Length/width/height
Number
Frame and cover/collar
Diagram/detail
Windows entrance
Ventilation
‰
‰
‰
‰
‰
‰
‰
10.
10.1
10.2
10.3
10.4
10.5
10.6
Conduit
Wall-to-wall measurements
Conduit identification
Placement method
Depth
Laterals
Maintenance hole (MH) size
‰
‰
‰
‰
‰
5.
5.1
5.2
5.3
5.4
Cable and Stubs
Reenterable/encapsulate
Type/gauge/size
Cable ID/pair count
Attachment height
‰
‰
‰
‰
‰
11.
11.1
11.2
11.3
11.4
Removals
Facilities lifecycle data
Cable length
Retire in place facilities
Record measurements
© 2007 BICSI®
10-17
OSP Design Reference Manual, 4th edition
Chapter 10: Design Documentation
Outside Plant (OSP) Construction Specifications Checklist, continued
General (Reference No. 1)
•
City/county (1.1)—The city or county where the work is performed.
•
Permits required (1.2)—Any permits that are required for completion of this project
should be attached to the construction drawings. These permits are typically necessary
during actual construction activity and may be required on site.
•
Service date/ship date (1.3)—The service completion of the project should be stated on
the work drawings. The ship date of any material, including vendor and telephone number,
should be on the drawings. This information is necessary to the construction work crew
when trying to understand the logistics of the project.
•
Million conductor feet (MCF [1.4])—Used when calculating the quantity of balanced
twisted-pairs or optical fiber strands placed in the plant. This is used by the accounting
staff to determine the average costs of facilities on a per conductor basis.
•
Copies to (1.5)—Other departments that have been sent or need copies of the
construction work drawing.
•
Service order information (1.6)—Service orders associated with the work project, the
numbers of the service orders, the number of line requests associated with them, and how
they will be integrated and completed.
•
Transmission information (1.7)—Any special transmission requirements for this project
(e.g., loading, capacitor build-out networks, optical attenuators, signal repeater or regeneration sites).
•
Billing (1.8)—Any special billing or invoicing arrangements that construction needs to be
aware of to complete this work project.
•
North arrow (1.9)—The north arrow should be on every work print.
•
Joint-use caution note (1.10)—Any joint-use caution notes for the work project.
•
Street names (1.11)—Street names and addresses should be indicated on the work plans.
•
Right-of-way (R/W) and easement information (1.12)—All R/W measurements and
easements should be noted on the work prints.
•
Distance to telecommunications ER/ultimate distribution point (1.13)—The kilometers
(km) and equivalent in kilofeet (kft) from the start of the project back to the equipment
should be noted. If this is a distribution area, the distance from the project location to the
end of the area should be stated. This point is typically known as the ultimate design point.
•
Symbols (1.14)—All symbols used on the construction work prints should adhere to OSP
design practices.
OSP Design Reference Manual, 4th edition
10-18
© 2007 BICSI®
Chapter 10: Design Documentation
Outside Plant (OSP) Construction Specifications Checklist, continued
•
Existing plant (1.15)—Any existing plant that may affect the successful completion of this
project or may be an integral part of the project; any utility company or third-party plant
that passes through the project work area; the owner of the plant, the telephone number,
and any limitations or cautions associated with their plant.
•
Joint trench bonding information (1.16)—Any grounding (earthing) or bonding information
or configurations appropriate for joint trench operations. Consult the most current edition
of local codes.
•
Special services (1.17)—Any special service circuits or lit strands working in the existing
cable that may require special handling.
Title Block (Reference No. 2)
•
Nature/necessity (2.1)—A brief description of the nature and necessity for this work
project
•
Work order/project number (2.2)
•
Voltage (2.3)—Identifies whether the working personnel will be exposed to the voltage of
power lines associated with this project.
•
Maintenance (2.4)— Any plant maintenance issues associated with this project that need
to be corrected at the time of the work.
•
Date and author (2.5).
Safety Requirements (Reference No. 3)
© 2007 BICSI®
•
Clearances/separations (3.1)—Identifies whether the power clearance and separations
are adequate to undertake this project.
•
Traffic lights (3.2)—Identifies whether traffic lights and vehicular traffic will need to be
managed to complete this project and whether permits are required to work in the streets.
•
Other utilities (3.3)—Other utilities in the general work area of the project (e.g., landscape
sprinklers) and their location. The one-call services typically do not locate privately-owned
utilities. State and country one-call numbers can be found in Chapter 5: Pathways and
Spaces.
•
Special notes for work personnel (3.4)—Any special notes regarding the environment or
construction area that the work personnel need to be aware of.
•
Pole condition (3.5)—Identifies whether the poles have been inspected and if the power
company performed the load calculations and provided permission to use their poles.
•
Direct-buried power (3.6)—Identifies whether there is direct-buried power in the area.
•
Safety requirements (3.7)—Identifies whether the customer has any special safety
requirements when working on their property.
10-19
OSP Design Reference Manual, 4th edition
Chapter 10: Design Documentation
Outside Plant (OSP) Construction Specifications Checklist, continued
Notes (Reference No. 4)
•
Existing facilities (4.1)
•
Shield continuity/conformance (4.2)—Has the cable shield been grounded and bonded
properly and is there conformance testing for the entire project?
•
Cable acceptance (4.3)—Has the cable been tested and accepted both prior to installation
and after construction?
•
Building terminal sketch (4.4)—Is the placing and splicing sketch of the building terminals
adequate?
•
Cutover drops (4.5)—Have the number of drops to be cutover and the terminal locations
on this project been identified?
•
Contact owner (4.6)—Identifies whether any affected customers have special
coordination requirements.
•
Sequence of splicing operations (4.7)—Identifies whether a sequence of splicing
operations have been prepared by the designer and whether a method of procedure
(MOP) should be written. A splicing sequence must be developed to ensure that any pair
or strand transfers or cable throws are done only after connectivity is established so that
customers or equipment nodes do not get disconnected. Technicians must understand their
obligation to follow the sequence as written and to coordinate with the designer if there is
a problem.
•
Scheduling (4.8)—Identifies whether any of the work should be performed after hours
and if customers have been notified.
Cable and Stubs (Reference No. 5)
•
Re-enterable/encapsulate (5.1)—Type of splice case and sealant or insulation.
•
Type/gauge/size (5.2)—Identifies whether the type/gauge and sizes of the balanced
twisted-pair cable match the design specifications.
•
Cable ID/pair/strand count (5.3)—Identifies whether the cable ID and pair or strand
count are correct.
•
Attachment height (5.4)—Identifies whether the strand size and attachment height are
specified on the work drawings.
•
Markers (5.5)—Type of cable markers specified for placement in direct-buried situations.
•
Obstructions (5.6)
•
Conduit or pipe (push or cut hard top surfaces [5.7])—Identifies whether the conduit will
be placed with horizontal directional boring, pushing, jack and boring or the pathway will
be open cut.
•
Reel number (5.8)—Identifies whether the cable reel numbers have been assigned to
project locations for appropriate setup and placing operations.
•
Measurements (5.9)—Identifies all the measurements available to complete the project.
OSP Design Reference Manual, 4th edition
10-20
© 2007 BICSI®
Chapter 10: Design Documentation
Outside Plant (OSP) Construction Specifications Checklist, continued
•
Pressurization and buffering material (5.10)—Identifies whether there is sufficient
pressure and buffering information if the work involves an underground conduit cable
system and if the material is available.
•
Fuse link (5.11)—Identifies whether all of the fuse links have been identified on the work
prints.
•
Final counts (5.12)—Identifies whether the balanced twisted-pair cable or optical fiber
strand counts are complete and correct.
•
Direct-buried drops (5.13)—Identifies whether all direct-buried drops to customers are
identified and routed properly.
Cable Terminals (Reference No. 6)
•
Type/size/count (6.1)—Identifies whether the terminal information is provided on the work
prints.
•
Protection/grounding (earthing) information (6.2)—Identifies whether the terminal
protection information is on the work prints.
•
Address/wiring limits (6.3)—Identifies whether the project requires wiring limits and if
they are provided on the work prints.
•
Backboard sketch (6.4)—Identifies whether there are inside building terminals and an
appropriate detail sketch of them and whether there is a drawing of the room where the
terminal will be located.
•
Terminal equipment/connecting blocks (6.5)
Poles (Reference No. 7)
•
Size/class (7.1)—Identifies whether pole size/class has been noted.
•
Staking information (7.2)—Identifies whether pole staking has been provided.
•
Joint use (7.3)—Identifies if there are any joint-use requirements.
•
Lead/height—Identifies whether the lead and height of guy and the pull on the pole have
been noted.
•
Span lengths (7.5)—Identifies the span lengths.
•
Caution notes (7.6)—Identifies caution notes.
•
CATV/electric company request (7.7)—Identifies whether there are any CATV or
electric company requests and if the electric company performed load calculations.
•
Pole removal (7.8)—Identifies whether pole removal information is shown on the work
prints.
Load Coils (Reference No. 8)
© 2007 BICSI®
•
Type case (8.1)—Identifies whether the correct type of splice case are noted on work
prints.
•
Pair count (8.2)—Identifies whether the balanced twisted-pair count for the load coil is
noted.
10-21
OSP Design Reference Manual, 4th edition
Chapter 10: Design Documentation
Outside Plant (OSP) Construction Specifications Checklist, continued
Maintenance Holes (MHs [Reference No. 9])
•
Length/width/height (9.1)—Identifies length, width, height, and headroom.
•
Number (9.2)—Identifies whether the MH is numbered.
•
Frame and cover/collar (9.3)—Identifies whether the frame and cover/collar are included.
•
Diagram/detail (9.4)—Identifies whether there is a MH diagram/detail layout of the
placing/splicing arrangements.
•
Windows entrance (9.5)—Identifies whether the MH windows entrance is straight,
splayed, or custom.
•
Ventilation (9.6)—Identifies the MH ventilation information.
Conduit (Reference No. 10)
•
Wall-to-wall measurements (10.1)—Identifies whether the wall-to-wall measurements
have been provided.
•
Conduit identification (10.2)—Identifies whether the conduit configuration has been
identified.
•
Placement method (10.3)—Specifies the placement method (e.g., direct-buried, concrete
encasement).
•
Depth (10.4)—Specifies the depth of the conduit placements.
•
Laterals (10.5)—Details the laterals’ measurements, angles, and directional information.
•
Maintenance hole (MH) size (10.6)—Specifies the size of the MH.
Removals (Reference No. 11)
•
Facility lifecycle data (11.1)—Identifies the date of removal date.
•
Cable length (11.2)—Identifies the cable length.
•
Retire in place facilities (11.3)—Notes any retire in place facilities. These facilities will not
be removed.
•
Record measurements (11.4)—Identifies whether all record measurements are available
and actions to ensure that the facilities to be removed are out of service and cannot create
troubles. For example, the splicer must contact the administrative center to verify that all
working pairs or optical fiber strands have been removed.
OSP Design Reference Manual, 4th edition
10-22
© 2007 BICSI®
Chapter 10: Design Documentation
Work Print Information Examples—Metallic Cables
Cables are identified by a four-letter code to simplify their designation for ordering,
manufacturing, and records. Additional information on cable coding may be found in reference
standards (e.g., ICEA P-61-694, Coding Guide for Copper, Outside Plant and Riser
Telecommunications Cables). Also see Chapter 3: Cable Types for detailed descriptions of
codes.
Figures 10.1 through 10.17 provide examples of work print drawings.
Figure 10.1 shows splicing together two sections of BKMA-200 cable, clearing and capping
the cable end.
Figure 10.1
Splicing together two sections of same cable
1
2
BKMA-200
01, 1-200
Figure 10.2 shows splicing in a section of cable where a cable order may have been shorted.
This causes an additional splice, noted in a change order, with the additional splice noted as
3A.
Figure 10.2
Splicing a shorted cable order
3
3A
52'
© 2007 BICSI®
BKMA-200
02, 1-200
10-23
OSP Design Reference Manual, 4th edition
Chapter 10: Design Documentation
Work Print Information Examples—Metallic Cables, continued
Figure 10.3 shows splicing together two cables of different sizes. Following the splicing, the
ends of the remaining pairs in the BKMA-900 are cleared.
Figure 10.3
Splicing two cables of different sizes
4
Future cable
BKMA-900
03, 1-900
BKMA-400
03, 1-400
Figure 10.4 shows splicing a new branch cable to a feed cable. A pressure plug is placed after
the splicing.
Figure 10.4
Splicing a new branch cable to a feed cable
6
7
P
BKMG-900
05, 1-900
BKMG-900
05, 1-500
100 XD
05, 601-900
BKMA-100
05, 501-600
OSP Design Reference Manual, 4th edition
10-24
© 2007 BICSI®
Chapter 10: Design Documentation
Work Print Information Examples—Metallic Cables, continued
Figure 10.5
New cables and a terminal spliced
NF-16P
BKMA-50
08, 1-50
08, 1-16
1
BHMA-50
08, 1-50
Figure 10.6
Cross-connect cabinet terminating gel-filled cables
AFMW-900
10, 901-1800
SA46
10, 901-1800
SA46, 1-1800
4
AFMW-900
SA46, 1-900
AFMW-900
SA46, 901-1800
© 2007 BICSI®
10-25
OSP Design Reference Manual, 4th edition
Chapter 10: Design Documentation
Work Print Information Examples—Metallic Cables, continued
NF-16P
X X
12, 51-66
Figure 10.7
Removal of NF-16 terminal
BKMA-100
12, 1-100
16
Figure 10.8
Replacing an NF-16 terminal with an NF-25 terminal
14
N
12
P
F-
25
X
16
51
P
6
X
,
-6
F-
N
,
5
-7
51
12
BKMA-100
12, 1-100
OSP Design Reference Manual, 4th edition
10-26
© 2007 BICSI®
Chapter 10: Design Documentation
Work Print Information Examples—Metallic Cables, continued
Figure 10.9
Energizing dead pairs
BKMA-100
(50 XD) 14, 51-100
14, 1-50 + 14, 51-100
BKMA-100
14, 1-100
Figure 10.10
Remove cross-connect terminal
1
BKMA-200
15, 1-200
© 2007 BICSI®
X
X
X
X
XXX
XX
BKMA 1-100
(AER2, 1-100) 15, 101-200
(15, 1-100 IN)
(AER2, 1-100 OUT)
10-27
OSP Design Reference Manual, 4th edition
Chapter 10: Design Documentation
Work Print Information Examples—Metallic Cables, continued
Figure 10.11
200-Pair cable transfer at splice
BKMH-600
4, 1-600
3
200
BKMH-400
(4, 1-400)
4, 401-600 + 200 XD
Figure 10.12
300-Pair cable transfer to new feeder cable
1
BKMA-600
12,1-600
BKMA-300
14, 1-300
OSP Design Reference Manual, 4th edition
300
BKMA-300
(14, 1-300) 12, 1-300
10-28
© 2007 BICSI®
Chapter 10: Design Documentation
Work Print Information Examples—Metallic Cables, continued
Figure 10.13
Section replacement on 300-pair cable
3
X X X X
BKMH-3
16, 301-600
BKMA-300
(16, 301-600)
BKMH-300
16, 301-600
4
Figure 10.14
Protector placement
Material
PL 145'
PL 18
35
36
37
5-302B1-100
3-302B1-100
A PL 145' ARMM-18
Building #1 entry wall
34
5-302B1-100
Vertical
5-302B1-100
PL 1800
ARMM-18
302B-100
W/50' STUB
4B1E protector units
4
1
INS.JT
A
ARMM-18
24, 1-1800
© 2007 BICSI®
B
2
3
10-29
See print #2
AFMW-1800
24, 1-1800
OSP Design Reference Manual, 4th edition
Chapter 10: Design Documentation
Work Print Information Examples—Metallic Cables, continued
Pannel Pl.
Rountdree Dr.
Figure 10.15
Sample maintenance hole plan and profile drawing
MH30
03
02
Williamson Rd.
6'
01
6'
50'
04
P 1497
M
H
31
Plan view
Profile
Conduit Summary
Length
Designed
Actual
Total
Conduits
Maintenance Hole Summary
Type
5'
2
Sec.
01
5'
2
02
D
B
85'
2
03
B
435'
6
04
B
MH30 12 by 6 by 7 Type A splay
MH31 12 by 6 by 7 Type A splay
MH = Maintenance hole
OSP Design Reference Manual, 4th edition
10-30
© 2007 BICSI®
Chapter 10: Design Documentation
Work Print Information Examples—Metallic Cables, continued
Figure 10.16
Butterfly detail worksheet
Locator coordinates:
Maintenance hole/Vault number:
Date:
Inspector:
Reinspection?
Y
N
Butterfly detail
1. Mark North point.
2. Identify as either:
• Magnetic North
• True North
• Site plan North
Provide:
Interior dimensions
• Ductbank
identifiers
Height:
• Ductbank
detail per wall:
Width:
Length:
– Number and
size of conduits
– Percentage of
fill per conduit
• Racking detail
• Splice case position(s)
Notes:
© 2007 BICSI®
10-31
OSP Design Reference Manual, 4th edition
Chapter 10: Design Documentation
Work Print Information Examples—Metallic Cables, continued
Figure 10.17
Butterfly detail
To MH E
900 PR, 09
2301-3200
(2) 24M/12S
F8 & F9
48M/224S
to facilities
(1) 400 PR, CA8
3201-3600
4" Conduit
(Typical)
Spare
Cut lead
25 PR
Telco
fiber
(1) 400 PR CA8
3201-3600
8M/4S
Building 5 to
power plant
(4) 45 F10,11,12,&13
900 PR, 09B
3601-4500
(4) 4S
F10, 11, 12, 13
(2) 24M/12S
F8 & F9
900 PR
3601-4500
900 PR
Telco
(1) 100 PR
unknown
50 PR
To power
plant splice
900 PR
Telco splice
(1) 50 PR
unknown
To Building 5
Maintenance
hole G
900 PR, 09B
3601-4500
900 PR, 09
2301-3200
3" Conduit
(Typ 4 places)
(1) 100 PR (Unknown)
900 PR Telco
Telco fiber
(1) 50 PR (Unkown)
Spare
(1) 8M/4S
Building 5 to
power plant
(1) 50 PR
To MH 7
3601-3650
N
09A
Power plant
BICSI
8610 Hidden River Pkwy.
Tampa, FL 33637-1000
800.242.7405
+1 813.979.1991
XYZ
Sheet No.
Drawn XX
Check XX
OSP Design Reference Manual, 4th edition
Date XX
10-32
Scale
Proj. No. XXX
Ref.
Dwg. X-XX
© 2007 BICSI®
Chapter 11
Cost Estimating
Chapter 11 describes the cost estimating procedures
for outside plant (OSP) design, including an example
of estimating cost for a small project, and recommends
suitable responses to change orders.
Chapter 11: Cost Estimating
Table of Contents
Development of Cost Estimating ....................................................... 11-1
Introduction .............................................................................................. 11-1
Scope of Work (SoW) ................................................................................. 11-2
Site Conditions .......................................................................................... 11-3
Outside Plant (OSP) Cost Estimating ................................................ 11-6
Introduction .............................................................................................. 11-6
Labor (Hourly or Unit) ................................................................................. 11-7
Materials (Item Cost Plus Delivery Fees) ........................................................ 11-8
Restoration (Hourly Plus Material or Unit) ....................................................... 11-9
Special Equipment Situations (Hourly Plus Material) ......................................... 11-9
Services, Fees, and Purchases of Licenses/Permits ....................................... 11-10
Estimating the Cost of a Small Project (Example) .......................... 11-11
Services Needed ...................................................................................... 11-12
Given ..................................................................................................... 11-12
Assumptions ............................................................................................ 11-12
Requirement ............................................................................................ 11-12
Labor ..................................................................................................... 11-12
Material .................................................................................................. 11-13
Equipment .............................................................................................. 11-13
Estimating Costs ...................................................................................... 11-13
Requesting and Responding to Change Orders ............................................... 11-15
© 2007 BICSI®
11-i
OSP Design Reference Manual, 4th edition
Chapter 11: Cost Estimating
Figures
Figure 11.1
New construction proposal to ABC corporate office ......................... 11-11
Tables
Table 11.1
Matrix for estimating costs .......................................................... 11-14
OSP Design Reference Manual, 4th edition
11-ii
© 2007 BICSI®
Chapter 11: Cost Estimating
Development of Cost Estimating
Introduction
Cost estimating is one of the keys to success in business life. The difference between survival
and elimination as a businessperson is being successful in business by engaging in one’s
endeavor and having a positive end result. Both the buyer and the seller should estimate the
cost of a project realistically. By doing so the:
•
Buyer receives a product that meets the designated requirements without paying an
excessive amount.
•
Seller makes enough profit after expenses to continue in business.
Because this arrangement is important to both parties, considerable effort should be spent in
developing cost estimates that both are accurate and provide some margin for comfort. Larger
entities could have separate organizations that provide this service, but a one-person
organization (e.g., plumber, electrician) must cover its costs and realize a profit to stay in
business.
Even a personal transaction (e.g., purchasing a car or an appliance) involves cost estimating.
Most people have an idea of what they are willing to spend before they enter the marketplace
to buy something. The figure could be accurate or inaccurate, and the consequences could be
of great or little significance. The more important the transaction, the more time a person will
spend getting the numbers right. The benefits are obvious, but the methodology for developing
the numbers is not.
Comparison shopping, seeking advice, or paying another to make the purchase in your name
are some methods used. Similarly, cost estimating in the industrial or commercial arena is not
done uniformly. Some rely heavily on experience and use historical records from past designs,
while others prefer to approach each new project as a unique entity.
Cost estimating is both an art and a science. It requires:
© 2007 BICSI®
•
An understanding of the work that has to be done.
•
Breakdown and quantification of the work by the labor skills required.
•
Identification and quantification of the material and equipment requirements.
•
Knowledge of the price of labor, material, and equipment.
•
Recognition of any special circumstances that will affect the project.
•
Familiarity with the site conditions.
•
Availability of the resources needed.
•
An understanding of direct management cost.
•
An awareness of unique conditions that will be present.
11-1
OSP Design Reference Manual, 4th edition
Chapter 11: Cost Estimating
Introduction, continued
The estimator gains the knowledge to bid by developing or reviewing a scope of work (SoW)
and by being familiar with the actual site where the work will be accomplished. This will
establish the particulars for a project. The knowledge of prices, availability of resources, and
other factors then can be applied.
The difference between cost and price is significant. The estimator should determine the
cost to the organization for doing the work described in the SoW. The price that is quoted
to a buyer will allow the contractor to recover the costs and other financial requirements
(e.g., overhead, operating expenses, profit). The words cost and price are not interchangeable.
Scope of Work (SoW)
The SoW is usually prepared to provide the basis for the work that is desired. It should
include:
•
A narrative description of the desired product.
•
Drawings.
•
Bills of material.
•
Material specifications.
•
A schedule.
While this is the basis on which most cost estimates are prepared, the document cannot fully
encompass the client’s needs and therefore cannot provide all the information desired by the
bidder. While this is less of a problem when the client issues the document, the work
requirement still needs to be validated so that the work priced is consistent with the client’s
expectation.
See Chapter 9: Scope of Work for a discussion on the contents of an SoW. If the reader is the
client or the contractor, there can be differences both in the expectation and in the content of
an SoW. A contractor will need to have all of the information described in Chapter 9 but can
find that the document is incomplete in several areas. A client can describe what is wanted
without clearly defining the manner in which it is provided or without defining the specific
process that should be followed.
If the SoW is not fully descriptive, the contractor should generate a cost estimate that provides
protection from a poorly worded and incomplete SoW. This incomplete SoW also can deprive
the contractor of presenting an appealing bid, since it could include contingencies that are not
needed or costs that should be avoided. Similarly, if the client is not fully forthcoming in the
description of what is wanted (the SoW could have been prepared by a consultant, who
interpreted the client’s requests), the client could find that the final product is a part of the
investment and could need to fund supplemental work to get the full product.
OSP Design Reference Manual, 4th edition
11-2
© 2007 BICSI®
Chapter 11: Cost Estimating
Scope of Work (SoW), continued
This chapter is written from the viewpoint of what a contractor should do in order to develop a
price proposal in response to a request for quote (RFQ). In a true win-win situation, both
parties benefit from having the project fully understood before entering into a contract or
offering and accepting a price. In many cases, clients have a staff that bid against the client’s
specifications in order to develop a basis for evaluating the bids that are submitted and to
determine the budget in advance.
Site Conditions
Identification of work that has to be completed to comply with the SoW normally will include
an invitation to do a site survey. This will provide availability to examine the site to validate or
understand the SoW prepared by others.
A site survey is a desirable and essential part of preparing a cost estimate for a client, whether
the client is seeking an engineering design only, a construction price only, or a turnkey project
where the bidder will offer a price to design and build. It also can be useful when a change
order or change in plan is requested for either the design or construction, although site
familiarity is normally assumed for these situations. A site visit, whether done alone or with
competitors for the work opportunity, will provide a chance to ask clarifying questions and to
evaluate site conditions that will affect costs.
Situations exist in which a site survey does not occur because of time constraints or the
expense involved with a site visit, but a cost estimate is still requested. In those cases,
the contractor would have to rely on the SoW alone, supplement the SoW with his own
knowledge of the site conditions, or rely on personal judgment and experience in producing
a price. Failure to conduct a site survey puts both parties at risk. A general rule is that site
surveys are necessary for most projects.
If a site survey is not conducted, some problems that could be encountered by the bidding
contractor are:
© 2007 BICSI®
•
Contingencies that can be added for protection that makes the estimate noncompetitive.
•
A costly impediment that is omitted in the pricing, which will obtain the contractor the
award but not the money needed to cover expenses.
11-3
OSP Design Reference Manual, 4th edition
Chapter 11: Cost Estimating
Site Conditions, continued
The site survey should allow the contractor to estimate the costs associated with the:
•
Design (if done for an engineering design survey).
•
Identification of skill sets, special equipment, and time required.
•
Estimation of total time required for the project, including a preliminary work schedule to
meet the client’s specifications.
NOTE: There are time conditions associated with schedules. The client could allow the
contractor to establish a schedule that meets the contractor’s capabilities or
specify the completion date as a requirement. If the client accepts the
contractor’s proposal, the job should be planned to allow effective use of
existing and available contractor assets. However, if the client has a specified
completion date, the contractor must determine the resources that are required
to complete the work within that time frame. In this instance, the contractor’s
cost estimate should include the cost of advertising for acquiring, training, and
employing additional workers or subcontracting a portion of the work. If the
contractor has insufficient resources, the contractor must increase the work or
plan on the use of overtime. If this is the case, the contractor must estimate the
additional payroll costs associated with the overtime required.
•
•
•
Evaluation of site conditions and the effect on cost and time, including labor estimating and
pricing. Labor prices include:
–
Fixed costs (e.g., mobilization, demobilization).
–
Variable costs (e.g., directly related to the amount of units consumed or expended).
–
Nonstandard costs (e.g., related to volume or duration of the activity but are not
linear—some can be stepped or graduated, like volume discounts).
Material takeoff and pricing that include:
–
A list of standards for the material requirements (acceptable substitutions for specified
materials that are not available).
–
Prices available for purchase of the materials required (e.g., cost of delivery, taxes,
storage at a staging point).
Equipment costs, including operation and maintenance.
OSP Design Reference Manual, 4th edition
11-4
© 2007 BICSI®
Chapter 11: Cost Estimating
Site Conditions, continued
•
Special site conditions that include:
–
Licenses, permits, and other approvals—Are these to be applied for or must they be
acquired? If acquired, the cost of acquisition could be more than the cost associated
with completing the forms. The fees could be high, attendance at meetings could be
required with regulatory authorities to justify the request, and there could be time lags.
The contract should reflect clearly what the client will do and what is expected of the
designer and contractor.
–
Hazardous materials and environmental concerns—If hazardous materials or environmental issues (e.g., wetlands) emerge, is the contractor expected to resolve them or
refer to the client for resolution? If the contractor is responsible, is this an item that
will be handled apart from the contract? If the client is responsible, who absorbs the
cost of the downtime?
–
Nonstandard hours (e.g., out-of-hours access, nights and weekends, specific time
frames, nonrush hours, nonworking hours)—If the contractor is obligated to pay the
employees for eight-hour workdays and does not get eight hours of useful employment, the bid price should address this.
–
Personnel restrictions (e.g., security clearances, special identification, citizenship)—
Some clients have restrictions against the employment of foreign nationals on their
premises or the use of employees who have criminal records or histories of substance
abuse.
The topics noted above should be addressed in the development of a cost estimate. The site
visit is intended to establish the conditions under which the work will be done. This site visit
will provide the contractor with information to enable a match of resources that should be
committed to accomplish the requirements of the SoW to the cost of providing those
resources. Once the information is understood, the estimated costs will need to be developed.
© 2007 BICSI®
11-5
OSP Design Reference Manual, 4th edition
Chapter 11: Cost Estimating
Outside Plant (OSP) Cost Estimating
Introduction
There are several ways to develop costs. For example, a craftsman could earn $XX per hour
and could earn this regardless of the actual time worked (e.g., sick time, vacation, training,
holidays). The employer has to cover these costs, plus other business expenses (e.g., Federal
Income Contributions Act [FICA], unemployment insurance).
In addition, employees could need to be provided with tools, uniforms, motor vehicles, and
other items. Some estimators include a factor to determine the price that should be charged
(e.g., loaded labor rate), while others use the raw costs (e.g., labor, material, equipment) and
subsequently factor them up to address overhead (e.g., other direct costs, general and
administrative costs). Others could rely on historical records from prior jobs and apply a price
per unit of property placed (e.g., inclusive of labor, material). In any case, the contractor has
to cover the cost of maintaining a properly equipped employee base while also making a profit.
The development of cost estimates requires the expenditure of time and labor for the bidder.
There is a balance between how thoroughly information is developed at the site visit and how
closely the actual cost of designing and building can be estimated. The extra time and cost
associated with a rigorous breakdown and pricing of work elements cannot be warranted.
Assuming that there are five contractors of equal competence, it would be reasonable to
figure that each will be awarded 20 percent of all opportunities over some period of time.
Therefore, the cost of the site survey and subsequent development of a cost estimate can be
factored five-fold to get the cost of estimating per job won. The profit margin on the job has
to cover these initial costs and still provide a profit.
Consequently, the more effective the cost estimating cycle is, the better the chances of
profitability for the contractor. The purpose of this chapter is to discuss how to effectively
prepare cost estimates that reasonably approximate the cost of doing the work but are not
too expensive to develop.
One approach to estimating costs is to quantify the work requirement by the type of labor
skill or crew required. Because outside plant (OSP) projects have conditions that warrant
specialized crews, cost estimating can be organized under crew assignments. This also
helps to determine scheduling issues associated with material availability and labor hour
assignments. When developing the cost of an OSP project, one of the first things the designer
should do is list all crew responsibilities.
OSP Design Reference Manual, 4th edition
11-6
© 2007 BICSI®
Chapter 11: Cost Estimating
Labor (Hourly or Unit)
An example of crew responsibilities, not necessarily all-inclusive, is shown below.
•
•
•
© 2007 BICSI®
Splice crews:
–
New splices cable and terminations/copper
–
New splices cable and terminations/fiber
–
Existing splices/dead splices/copper
–
Existing splices/dead splices/fiber
–
Throws/copper
–
Throws/fiber
–
Jumper rearrangements/copper
–
Jumper rearrangements/fiber
–
Testing for all circuit provisioning
–
Air pressure control setup
Aerial crews:
–
Locating existing utilities
–
Tree trimming
–
Pole replacement
–
Cable rearrangements
–
New cable placement
–
New pole line
–
Cable replacement
–
Cable removals
–
Pole removals
–
Aerial drop wire
–
Bridge attachments/hardware
Underground crews:
–
Pulling new cable in conduit
–
Maintenance holes (MHs) setup/barricade and purge
–
Air pressure equipment placement
–
Racking cables
–
Rearrangement of racked cables
–
Removal of cable in conduit
–
Innerduct placement
11-7
OSP Design Reference Manual, 4th edition
Chapter 11: Cost Estimating
Labor (Hourly or Unit), continued
•
•
Buried/conduit crews:
–
Locating existing utilities
–
Right-of-way (R/W) clearing
–
Splice pits
–
MH/conduit placement
–
Buried cable placement
–
Innerduct placement
–
Boring
–
Erosion control measures
Drop crews (direct buried):
–
Plowing drop wires
–
Placement of drop pedestals
–
Storage of temporary wire
Materials (Item Cost Plus Delivery Fees)
Similarly, the materials needed to support these crews in their work should include the
following.
•
•
•
Splice crew:
–
Aerial/buried terminals
–
Splice cases
–
Splice connectors
Aerial crew:
–
Strand
–
Cable
–
Anchors/push bracing
–
Poles
–
Miscellaneous hardware
Underground crews:
–
MHs
–
Conduit
–
Miscellaneous hardware
OSP Design Reference Manual, 4th edition
11-8
© 2007 BICSI®
Chapter 11: Cost Estimating
Materials (Item Cost Plus Delivery Fees), continued
•
Buried crew:
–
Pedestals
–
MHs
–
Conduit
–
Warning/locator tape
–
Aboveground markers
Restoration (Hourly Plus Material or Unit)
Further definition of the work breakdown should include the following associated requirements
for restoration of the area to its preconstruction state as a separate item of work:
•
Asphalt
•
Concrete
•
Gravel
•
Grass seed and sod
•
Shrubbery
•
Curb and gutter
•
Backfill
Special Equipment Situations (Hourly Plus Material)
Special equipment beyond that normally associated with a worker, but required for the specific
project, can be identified and included in the pricing module.
This should include the following items.
© 2007 BICSI®
•
Large directional boring equipment and support materials (casings)
•
Cranes for material placements:
–
Bridge accessibility
–
Extra-tall access
•
Sizeable backhoe jobs
•
Special traffic control measures
•
Large clearing jobs
•
Waterway crossing access
•
Submarine cable placement
•
Fiber blown cable equipment
•
Cast-in-place MH construction
11-9
OSP Design Reference Manual, 4th edition
Chapter 11: Cost Estimating
Services, Fees, and Purchases of Licenses/Permits
Specific fees or costs associated with the project should be included in the pricing:
•
Designer’s fees
•
Inspector’s fees
•
R/W consultant’s fees
•
Material costs associated with design (e.g., maps, documents, plotting)
•
Fees for permit applications and land-settlement costs:
–
Railroad permits
–
City, county, or state permits
–
Interstate permits
–
Recording fees for easements or land titles
–
Cost of land purchase settlements
–
Cost of traffic diversion
•
Environmental considerations
•
Fees for makeready work on aerial construction
OSP Design Reference Manual, 4th edition
11-10
© 2007 BICSI®
Chapter 11: Cost Estimating
Estimating the Cost of a Small Project (Example)
Figure 11.1 illustrates one approach to estimating the costs for a small project.
NOTES: This drawing is not a fully detailed engineering document, but rather a basic representation to demonstrate basic components for the purpose of a cost estimate.
Prices quoted in this example are used to show the designer one possible way to
estimate a job and should not be used on actual bids since the cost for labor, material, and equipment varies from state to state and in different countries.
Figure 11.1
New construction proposal to ABC corporate office
1
5
3
Place ANMW-50
3, 501-550
137 m (450 ft)
Place new anchor and guy
Place 9 m (30 ft)
Class 7 Pole
4
Place u-guard on pole
2
B
B
B
Pole 4
30' 7
1
6
B
Building entrance
Place 6.6 M
strand between
poles
50
Office complex
8
x
Remove existing guy and anchor
7
Pole 3
Splice to existing
Place 50 pair terminal
2
Pole 2
BKMA-100
3, 501-600
Pole 1
MH 1
ANMY-6
3, 1-600
ANMY-6
3, 1-500+
100 XD
1
1
= Existing pole
= Splicing operation with sequence number
= Placing operation with sequence number
ft = Foot
= Splice
m = Meter
= Anchor and guy
MH = Maintenance hole
B
= Buried cable
= Protected terminal
© 2007 BICSI®
11-11
OSP Design Reference Manual, 4th edition
Chapter 11: Cost Estimating
Services Needed
ABC Corporation requires 30 pairs for telecommunications.
Given
The existing cable in MH 1 feeds a 100-pair aerial cable that extends from Pole 1 to Pole 3.
New 50-pair cable and strand (shown in bold) will be placed from existing Pole 3 to a new
Pole 4. The cable will extend vertically to the base of the pole and be placed in a 0.6 meter (m
[2 foot (ft)]) deep trench to the building. Cable will be routed up the wall and placed into the
building at a height of 2.4 m (8 ft). A U-guard will serve to protect the cable on the outside of
the building and up the pole.
The cable will terminate on a 50-pair protected terminal that is properly bonded and grounded.
Assumptions
There are no unusual factors that would adversely affect the bid. The design as shown is not
negotiable. The design engineer has completed the site survey.
Requirement
Develop the cost of constructing this project. The information from the site survey should
allow the job to be broken into the following elements:
•
Length and type of cable to be placed
•
Whether the route will be aerial, buried, or in conduit (or some portion of each)
•
Numbers of poles to place or make ready
•
Numbers of splices to design
•
Route followed
•
Any special equipment requirements (e.g., road boring equipment, digger trucks, plows)
This information is further divided into the:
•
Estimated length of each type of cable.
•
Number of pairs to be spliced.
•
Characteristics of the route (e.g., field or roadside pole attachments, rocky or swampy
soil, private property, public R/Ws).
Labor
A crew will be required to remove an anchor and guy at Pole 3, set a new pole (4), and place
a new anchor and guy. The crew will place 66 m (216 ft) of 50 pair cable and 6M strand
between poles 3 and 4. Extend the cable down the pole and trench 137 m (450 ft) into the
building.
A splicing crew will splice 50 pairs on a fixed count protected terminal that will be properly
bonded and grounded. They also will straight splice the new cable into the existing at Pole 3.
Surfaces will be restored to original or better condition upon completion of the work activities.
OSP Design Reference Manual, 4th edition
11-12
© 2007 BICSI®
Chapter 11: Cost Estimating
Material
Major components include:
•
Cable types and lengths.
•
Poles, guys, and anchors.
•
Protected terminals.
These pieces are identified and priced individually. Miscellaneous hardware (e.g., bolts,
clamps, U-guards) usually is not priced separately unless requested by the customer.
Equipment
Heavy equipment will be required to place the pole and anchor and to remove the existing
anchor.
Estimating Costs
Once the job components have been identified, they can be inserted into existing tables that
contain unit prices based on experience or actual compilation of data locally developed.
Table 11.1 is one example that can be used.
NOTE:
© 2007 BICSI®
The unit price data shown is totally illustrative and not representative
of any actual job.
11-13
OSP Design Reference Manual, 4th edition
Chapter 11: Cost Estimating
Estimating Costs, continued
Table 11.1
Matrix for estimating costs
Item
Description
Number Material
of Items Cost per
Estimated
Material Cost
Labor Cost
per Item
Estimated
Labor Cost
Estimated
Total Costs
Item
Install U-guard 51 mm (2 in)
(riser)
Each
2
$32.04
$64.08
$8.24
$16.48
$80.56
Install aerial cable ANMW-50
Foot
220
$0.90
$198.00
$1.50
$330.00
$528.00
Install cse on old cable
Each
1
$139.92
$139.92
$12.00
$12.00
$151.92
Install direct-buried copper
Foot
450
$0.90
$405.00
$5.50 $2,475.00
$2,880.00
Install term 50 pr
Each
1
$210.00
$210.00
$75.00
$75.00
$285.00
Splice copper
Pair
100
$0.50
$50.00
$1.00
$100.00
$150.00
Set 9 m (30 ft) pole
Each
1
$300.00
$300.00
$80.00
$80.00
$380.00
Place anchor
Each
1
$40.00
$40.00
$40.00
$40.00
$80.00
Place down guy
Each
1
$5.00
$5.00
$20.00
$20.00
$25.00
Remove anchor and guy
Each
1
$0.00
$0.00
$20.00
$20.00
$20.00
Restoration of buried route
Lump sum
1
$0.00
$0.00
$300.00
$300.00
$300.00
$3,468.00
$4,880.48
TOTAL PRICE
ft
in
m
mm
=
=
=
=
$1,412.00
Foot
Inch
Meter
Millimeter
OSP Design Reference Manual, 4th edition
11-14
© 2007 BICSI®
Chapter 11: Cost Estimating
Estimating Costs, continued
The estimated cost for this example is $4,880.48—comprised of $528.00 for the aerial section,
$2,920.28 for the buried section, $545.28 for the structural work (poles, anchors, and guys),
$586.92 for the splicing, and $300.00 for restoration.
The table does not include any statement that addresses allowances for weather delays,
equipment failure, or other contingency conditions that could drive the time and cost higher.
Moreover, no clarifying assumptions have been included. Any response should include the
assumptions upon which it was based so that any future discussions will have the same basis.
Note that no schedule is provided. A complicated job will require a schedule to be factored
into the estimating process. One product of a cost estimate is the calculation of the hours
needed to complete the tasks. This allows a schedule to be established. Most SoWs specify
a target completion date. The amount of time available from the award of a contract to the
delivery date sets the parameters in which the required labor hours or equipment hours for
completing the design or construction should be accomplished (or for acquiring the licenses
and permits). This establishes the crew sizes, equipment usage, and material delivery intervals.
If any of these result in an unusual drain on the available resources, it could affect the:
•
Number of crews that are required.
•
Need for extraordinary schedules (e.g., shift work, weekends, overtime).
•
Substitution of materials that cannot be acquired in the time available.
•
Need to modify the design to avoid time-consuming impediments.
These factors could affect the initially developed cost estimate. A final cost estimate can
require several iterations of the estimating process to ensure that all influencing factors have
been considered.
Any tabular system for estimating should be checked for rationality once a number has been
developed. Reliance on a spreadsheet price estimate without doing a sanity check can lead to
considerable discrepancy from the actual cost. For example, although a unit labor cost can be
historically accurate, if unusual conditions are experienced (e.g., night work only, double shifts,
limited access time during the work period, mandatory overtime), the rates will have to be
adjusted or the overall labor price will have to be modified.
Additionally, if a job takes six labor hours to complete, it is unlikely that the employee will
be able to gainfully perform other tasks that day, so it suggests that a full eight-hour cost be
estimated. Similarly, if vendors’ prices fluctuate, a more costly substitute has to be used
because of schedule demands, or the product normally used is unavailable, adjustments should
be made.
The effort in placing a 50-pair cable is not much different than placing a 25-pair. Whether
the estimating template used should address such fine differences is up to the estimator to
determine. Usually, reliance on judgment and experience is used to supplement the basic
number produced from the spreadsheet.
© 2007 BICSI®
11-15
OSP Design Reference Manual, 4th edition
Chapter 11: Cost Estimating
Estimating Costs, continued
In today’s environment of electronic data processing and computer availability, software
programs are available for estimating construction prices. These software programs should
be evaluated for availability and effectiveness. Any cost data needed should be validated
for regional differences, current economic climate, and other factors.
Maintaining an accurate price database can become a time-consuming task. However, a
pricing program created for estimating telecommunications design and construction costs
can be useful, since it will save time or allow more time to focus on the identification and
quantification of the work elements in the project.
Requesting and Responding to Change Orders
Change orders are a serious issue, because the contractor can be expected to work quickly
to address the item in order to maintain the schedule. This urgency brings risks. Occasionally,
the requester is not the authorized client agent, and the cost or the work itself is not consistent
with client requirements. The contractor agent on site (usually a foreman or lead technician),
in an effort to please the requester, can make changes and incur charges that are not
compensable. These changes could impact the design itself and the functionality of the
finished product.
The entire issue of the acceptable procedure for requesting and responding to change orders
is one that should be covered in detail either in the contract (preferably) or with the client
before work begins. The procedure can spell out the time frame for the contractor to respond
with a redesign or a price for the changes, but it should be predicated upon getting a clear
SoW describing the modification. This change order shall come from an authorized agent of
the client and be responded to by an authorized contractor agent.
An example of such a procedure would be the following:
•
The authorized client representative defines the change (e.g., addition, deletion, other
modification) to the work. This change is spelled out in writing. If it is offered verbally,
the contractor also should put the request in writing and get the document signed.
•
The contractor accepts the proposed change order and agrees to respond with a price
for the work within a specific time frame (e.g., two days for a minor [$5,000] change,
one week for a change that could require investigation of available material, equipment,
impact of change on the design).
•
The contractor provides the proposed price to the client representative, along with a
statement of the impact of the change on the timeline of the project.
•
The client representative accepts or declines the price and the associated work.
It is desirable to develop the actual procedure for change orders and include it in the contract
language. If no agreement is reached, some contracts could specify that the contractor be
required to do the work specified, retain records of the costs of doing so, and subsequently
negotiate a price with the client or submit the dispute to binding arbitration.
OSP Design Reference Manual, 4th edition
11-16
© 2007 BICSI®
Chapter 11: Cost Estimating
Requesting and Responding to Change Orders, continued
The client may feel that the time loss associated with amending the issue is potentially more
damaging than the consequences of clashing with the contractor. The contractor should be
aware of the implications of these situations before they arise and have contract provisions to
address them. If this is not done in advance, the contractor and client both should have a clear
understanding of what is being requested and what is being priced, as well as any impact on
the overall project.
The process of estimating the cost of change orders is no different from that of estimating
the cost of a new job and can be done in the same way as described above. The cost to the
contractor usually should be less than that of a new job of equal dimensions since the crew is
already familiar with the environment and the up-front costs of mobilization are not pertinent.
However, since this could be a noncompetitive bid situation, the owner should evaluate the
price offered carefully and seek an independent estimate to be satisfied the price is
reasonable.
There could be an option to defer the work or use some other vendor if the price is
unreasonable. Some contracts contain clauses allowing the owner to demand that work be
done under a change order and negotiate the price later, or the change orders are submitted
to an arbitrator for a decision.
© 2007 BICSI®
11-17
OSP Design Reference Manual, 4th edition
Chapter 12
Maintenance and
Restoration
Chapter 12 addresses the issues of outside plant (OSP)
facility maintenance, describing routine and demand
maintenance and emergency restoration procedures.
Chapter 12: Maintenance and Restoration
Table of Contents
Maintenance of Outside Plant (OSP) Facilities .................................. 12-1
Introduction .............................................................................................. 12-1
Outside Plant (OSP) Infrastructure Characteristics .......................................... 12-1
Maintenance Practices ................................................................................ 12-2
Detailed Maintenance Plan ........................................................................... 12-3
Routine Maintenance .................................................................................. 12-4
Demand Maintenance ................................................................................. 12-7
Emergency Restoration Procedures .................................................. 12-9
Address Critical Elements ............................................................................ 12-9
Restoration Issues ................................................................................... 12-11
Operations Support Centers ....................................................................... 12-12
Operations Support Center Locations ..................................................... 12-14
Summary ................................................................................................ 12-15
Tables
Table 12.1
Routing maintenance checklist ......................................................... 12-4
Table 12.2
Demand maintenance ..................................................................... 12-8
Table 12.3
Emergency restoration issues ........................................................ 12-11
© 2007 BICSI®
12-i
OSP Design Reference Manual, 4th edition
Chapter 12: Maintenance and Restoration
OSP Design Reference Manual, 4th edition
12-ii
© 2007 BICSI®
Chapter 12: Maintenance and Restoration
Maintenance of Outside Plant (OSP) Facilities
Introduction
The establishment of guidelines for managing and maintaining communications systems and
infrastructure is essential to the support of telecommunications infrastructure in any
environment.
There are differences between the maintenance and the restoration of outside plant (OSP)
infrastructure, even though both fall under the general description of maintenance.
Maintenance is associated with ensuring the continued operability of an existing facilities
network within the operating boundaries of the owner. Restoration requires the reestablishment of components following their failure. The information in this chapter applies to balanced
twisted-pair, optical fiber, or any other transmission medium.
Outside Plant (OSP) Infrastructure Characteristics
A quality designed, reliable OSP infrastructure that is easily maintained must be based on the
following criteria:
•
Sound engineering and detailed design practices
•
Quality construction using premium materials while establishing the OSP infrastructure
•
As-built drawings and cable records
•
Spare ducts, optical fiber strands, and balanced twisted-pairs for future growth and
expansion
•
Route diversity preventing service failures (enhance survivability)
•
Complete and detailed as-built documentation
•
Spare equipment capacity to ensure availability for rapid response to service interruptions
•
Adequate equipment spares for mean time between failures (MTBF)
NOTE:
© 2007 BICSI®
Consider using a ring, mesh, or star topology for optical fiber OSP networks.
12-1
OSP Design Reference Manual, 4th edition
Chapter 12: Maintenance and Restoration
Maintenance Practices
Maintenance practices can be divided into several categories. One such basic separation is
the distinction between routine and demand maintenance. Every OSP infrastructure requires
ongoing maintenance. Age, exposure to weather, and other factors may cause the need for
maintenance. The purpose of maintenance is to extend the useful life of the installed plant.
OSP products have varying life expectancies. Items like poles and conduit are expected to last
for many years. Cables have a shorter duration but still can be useful for 30 to 40 years. It is
not uncommon to find creosoted wood duct still carrying lead-sheathed cables, although for
many reasons (e.g., capacity, service, environmental concerns) these are unusual situations.
The initial capital investment is only a fraction of the total cost of maintaining the facility
during its useful life. Consequently, there is a strong need to design the OSP in the above
standard manner from the initial installation minimizing the long-term cost of keeping it in
service. The facility shall be maintained during its life cycle with routine inspection and
maintenance of all spaces, pathways, and splice enclosures to extend and enhance the
network performance capabilities.
Many of today’s OSP products are associated with analog and digital electronic technology.
The development and evolution of these products continue even after they have been put into
service, so each succeeding generation may be smaller, faster, more competent, more robust,
or another combination of desirable features.
The decision of when to replace existing OSP is usually an economic one. It may be better to
remove a component with a remaining life in order to upgrade the capability of the OSP
infrastructure, rather than to extend the life and live with a (comparatively) reduced capability.
The choice to augment the existing plant or to remove and replace it is determined by the age
and the condition of the facility. This decision also is influenced by the available capacity of
the support structure (e.g., joint-use or solely owned pole lines, available conduits, utility
tunnels, right-of-way [R/W] access).
This chapter is concerned with how to obtain the maximum use of installed components.
Determining when to replace OSP that has remaining life is an economic one and will not be
addressed in this chapter. The OSP engineer or information transport systems (ITS)
distribution designer must be prepared to provide cost justification documentation for the
expenditure of funds to augment the network.
OSP Design Reference Manual, 4th edition
12-2
© 2007 BICSI®
Chapter 12: Maintenance and Restoration
Detailed Maintenance Plan
System maintenance starts with a complete and thorough understanding of the network and its
associated documentation. A detailed maintenance plan must be established and in place to
ensure smooth system maintenance.
At a minimum, the system maintenance plan must address the following items:
© 2007 BICSI®
•
Personnel availability and skill set requirements.
•
Product training that includes hands-on familiarization with new products.
•
Codes, standards, and safety training to maintain skill levels to minimize substandard work
habits.
•
Current documentation with detailed records of circuits, optical fibers, and cables.
•
Cable records maintained for the OSP staff to identify potential issues that affect service.
•
Up-to-date pathway segment records with mandrel and rodding history.
•
Current maintenance hole (MH [butterfly]) detail drawings with callout notes on the
master record maps.
•
Installed equipment baseline—This includes the current version of installed equipment,
documented option settings, port configurations, and other items of information needed for
the repair or restoration of individual circuits.
•
Storage and availability of repair materials—Included with this item are the procedures
and process necessary for the replenishment of materials as they are used. Some quantity
of materials must be available to the restoration teams on a 24/7 basis. The maintenance
plan must address how this material is to be obtained by the restoration team outside the
normal working hours of the support center.
•
Initial and sustaining training—The maintenance plan must establish guidelines for training
of the initial skill sets necessary for normal operations as well as provide a method for
ensuring continued development of the workforce needed. Backup personnel must be
available for long-term support and operations.
•
Restoration procedures—The maintenance plan must establish policies and practices for
the routine maintenance and support of the system, demand maintenance, response to
requirements driven by public demand (e.g., road moves, customer demands), or natural
events (e.g., floods, lightning hits, structural failures). In the event of unplanned system
outages, along with the policies and practices for routine and demand maintenance, special
procedures and policies must be established for emergency or quick system recovery.
•
Maintenance schedule for all OSP equipment, including periodic testing and calibration.
•
Management escalation procedures with contact information for emergency callout of all
of the workforce.
•
Warning tapes installed with all new buried and underground construction.
12-3
OSP Design Reference Manual, 4th edition
Chapter 12: Maintenance and Restoration
Routine Maintenance
Routine maintenance is the periodic and continued examination of the facilities for abnormal
conditions (see Table 12.1). This may be done by physical inspection or by using sophisticated
network monitoring and surveillance systems that can detect abnormalities in the facilities
(e.g., changes in resistivity, indications of loss of sheath integrity, moisture intrusion, similar
indications of degradation).
Table 12.1
Routine maintenance checklist
Description
Frequency of
Maintenance
Note:
Inspect all ground locations and
connections.
Ongoing
Report any defective conditions for
immediate corrective action.
Inspect building entry points for
possible seepage.
Ongoing
Inspect after any work is performed in
building entry room.
Inspect all conduit duct systems.
Ongoing
After any and all work in MHs and EFs
seal all ducts.
Inspect and pump MHs, vaults,
and PBs.
Ongoing
After all heavy rains and in areas prone to
freezing during and after all thaws.
Cleaning of MHs, vaults, and PBs.
Ongoing
Work activity shall dictate. Prepare report
if required.
Seal all ducts vacant and occupied.
Ongoing
Work activity shall dictate. Prepare report
if required.
Outside splice enclosure inspection.
Ongoing
Work activity shall dictate. Prepare report
if required.
Route inspection of buried routes for
potential damage.
Ongoing
To determine if any activity has impacted
the route, prepare report and
take corrective action.
Routine inspection of utility tunnels in
large campus sites.
Ongoing
To determine if any activity has impacted
the route, prepare report and
take corrective action.
EF = Entrance facility
MH = Maintenance hole
P B = Pull box
OSP Design Reference Manual, 4th edition
12-4
© 2007 BICSI®
Chapter 12: Maintenance and Restoration
Routine Maintenance, continued
These monitoring systems are designed to be preventive and do not affect service. They are
proactive and designed to detect that a failure may be imminent. The network monitoring and
surveillance systems enable the targeted dispatch of a technician without routinely spending
time covering cable routes that are not in a pre-failure mode.
Routine maintenance frequently gets less support because it is difficult to place a value on
trouble reports not received and repaired as opposed to the cost of the routine maintenance
program. Routine maintenance involves more than looking for potential problems. It ensures
that the OSP infrastructure is safe and that employees and the public are not exposed to
dangerous conditions.
As a result, maintenance includes ensuring cabling/optical fiber integrity, as well as verifying
that:
•
Poles, guys, and anchors are sound.
•
Route markers are in place to protect buried and underground routes of the OSP network.
•
No dangerous electrical conditions have developed from unauthorized attachments,
defective grounds, or missing grounds. Verification also includes compliance with safety
regulations of the authority having jurisdiction (AHJ).
Some specific programs that would fall under routine maintenance include:
© 2007 BICSI®
•
“T” zone inspections for aerial plant—The area includes the cable attached to a pole and
extending 0.91 meters (m [3 feet (ft)]) to either side (effectively forming a “T” when
viewed as a segment), which can be a major area of trouble. This zone normally includes
the terminal, service wire attachments, and splices. It is a location for high technician
activity. Owners will focus their routine maintenance efforts here, checking that splices
and splice cases have integrity, terminals are clean (e.g., no dead service drops, no wasp
nests or rodent intrusion, no open covers), poles are structurally sound, clearances are up
to standard, and any attachments by foreign companies are authorized and compliant.
•
Tree trimming—Periodic tree trimming is necessary to prevent problems of sheath
abrasion or damage that degrades transmission capabilities. Routine tree trimming and
vegetation management is required in pathways that are off-premises and cross-country
or along R/Ws with overhanging tree branches. Annual work is usually required for this
process. Chemical foliage management may be utilized, providing the AHJ allows for its
use and it adheres to environmental regulations.
•
Pole inspections—Poles are periodically checked for pole deterioration, sufficient pole
height to carry the facilities, unauthorized attachments (this is similar to “T” zone
inspections but does not involve climbing the pole to check for grounding, bonding
(earthing), and terminal face plate conditions), or any other abnormalities (e.g., defective
guys and anchors or ground wires). Pole inspections ensure employee and public safety
and that clearance infractions are reported and cleared.
12-5
OSP Design Reference Manual, 4th edition
Chapter 12: Maintenance and Restoration
Routine Maintenance, continued
•
Buried cable terminal maintenance—Similar to aerial terminals, the conditions of the
terminal and surrounding environment are checked for items like housekeeping (e.g., dead
jumpers, stenciling, pea gravel, corrosion, rodent damage) and vandalism. This program
includes large cross-connect interfaces and smaller distribution terminals, while other
programs focus only on serving area interfaces because of normal high activity.
•
Maintenance of underground facilities (including underground terminals in MHs)— Debris
and contamination can enter MHs and utility tunnels through conduits, cracks in the walls
caused by earth movement, and covers not properly sealed. Moisture seepage will enter
through joints of prefabricated units (MHs) not properly installed. These can damage
cables, splices, and MH hardware if ignored and can create an unsafe environment for
workers.
•
Maintenance of OSP identification methods—OSP is labeled or stenciled for easy
identification. Over time, labels become damaged, fall off or fade, and become illegible.
The owner of OSP should maintain proper labeling. Labels are required for identification
and to contact the owner in case of emergency, damages, or relocation needs. The system
should be standardized and clear to anyone who needs to know the owner of the plant.
•
R/W inspections—Routes designed through R/W may become impaired due to tree
growth, the facilities of others, or encroachments. R/Ws may be managed by surveillance
and routine inspections. Personnel assigned to this task may have to request the removal
or relocation of these encroachments on OSP R/Ws. An R/W grant occasionally must be
defended.
•
Air pressure maintenance—The text in Chapter 13: Special Design Considerations
explains the need to maintain existing air core cable facilities protected by air pressure.
Various air pressure monitoring systems are commercially available to identify the location
of air leakage above target levels and to effectively direct labor to locate and fix leaks
before cables become wet. Pressure and cable maintenance activities should be
consolidated where practical for efficiency and to avoid duplication of efforts.
•
Defective cable pair recovery program—Depending on the demand for spare pairs, it may
be useful to identify locations where a cluster of defects exists and attempt to recover
these pairs. Defects usually occur at splice and termination points, as opposed to within
the sheath. At such locations, minimal effort can recover a number of cable pairs or
prevent a potential future failure. Entering splices where a substantial number of bad pairs
have been traced may be counterproductive and should be identified not to be entered
•
OSP pathway structures (e.g., MHs, tunnels, substructures) are required to be inspected
periodically to ensure their integrity from potential damages from earth movement, ground
thaw, earthquakes, or construction activity by others.
OSP Design Reference Manual, 4th edition
12-6
© 2007 BICSI®
Chapter 12: Maintenance and Restoration
Demand Maintenance
Demand maintenance may be caused by requirements, such as:
© 2007 BICSI®
•
Responding to facility location requests from underground location services or one-call
centers. This is a mandated requirement in many jurisdictions and usually has a finite time
frame for the response. It is a significant factor in reducing the amount of service
interruptions caused by earth removal.
•
Responding to customer service demands.
•
Relocation of OSP due to road improvements—OSP located within a public R/W may
require relocation at the owner’s expense because of road rebuild or relocation. This
requirement varies by jurisdiction. With a secured easement, the cost for relocations may
allow for billing back to the agency doing the improvements, but the relocation will still be
required at the agency’s schedule. The property owner has the right to improve or widen
within their area.
•
Site improvements (e.g., drainage problems).
•
Property additions that conflict with existing OSP (e.g., new buildings, driveways),
whether aerial, underground, or buried.
•
Changes in clearance, separation, and general pole spacing.
•
Obligations under joint-use agreements—One advantage of joint-use agreements is that
the cost of occupancy for the parties is reduced. An obligation exists to rearrange the
OSP to accommodate the other user, replace the pole for additional height and clearance,
or conduct periodic inspections to ensure compliance with joint-use regulations.
Recordkeeping is an administrative requirement since both the user and the owner want to
be sure that the costs are properly allocated. Joint-use administration is generally
processed and the records updated through a third-party organization (e.g., joint pole
authority). The administrative costs are shared by the member parties, and the obligations
under each of these situations are understood when the agreement is negotiated. These
obligations may include:
–
Rearrangement—Whenever the OSP is located on joint-use pole lines, the requirements of other authorized tenants or the pole owner may necessitate rearrangements
of the cables. This may be as simple as transfering and raising the facilities or as
complex as relocating to newly located poles. An OSP engineer or designer should be
assigned to address these requests and to handle design, negotiation, and administrative requirements.
–
Pole replacement—Poles may need to be replaced because of damage, clearances, or
other reasons. Depending on the agreement, the pole owner may do the replacement
and plant transfers for all parties (this is rarely done due to safety issues handling the
facilities of others) or may require each tenant to do its own. This requirement should
be understood in advance (joint-use documentation spells out what is to be done by
the occupants of the pole in question). If the owner of the pole does the work, this
cost will be billed back to the OSP owner. If the OSP owner performs the work, an
appropriate contractor workforce should be available on demand to provide this
service.
12-7
OSP Design Reference Manual, 4th edition
Chapter 12: Maintenance and Restoration
Demand Maintenance, continued
•
Response to network monitoring and surveillance systems that indicates imminent trouble
to a pressurized cable. Pressure monitoring equipment will provide valuable information
for locating potential damages before an outage occurs.
•
Changes in road elevation (e.g., repaving, rerouting) that require changes in the thickness
(depth) of the MH collar.
Demand maintenance also can be caused by damage to the facilities through weather, motor
vehicle collisions, road washouts, floods, and physical degradation (see Table 12.2). The
damage may or may not create an out-of-service condition. Hazards to the public or the risk
of losing the facility will require an immediate response. These conditions are addressed in
detail later in this chapter.
Table 12.2
Demand maintenance
Description
Frequency of
Maintenance
Note:
Network monitoring and surveillance
systems.
Ongoing
All detection reports reviewed and
dispatched if required.
All reports logged and disposition.
Ongoing
All incident reports cleared and
recorded.
Inspect and pump MHs, vaults, and PBs.
Monthly
After all heavy rains and in areas prone
to freezing during/after all thaws.
Cleaning of MHs, vaults, and PBs.
Ongoing
If the MH/PB is entered, it should be
left clean. An incident report is to be
written and logged for follow-up work.
Seal all ducts vacant and occupied.
Ongoing
Incident report to be written and logged
for follow-up work.
Outside splice enclosure inspection.
Seasonally
Visual inspection only unless cause for
breaking the seal.
Route inspection of buried routes for
potential damage.
Ongoing
Inspection of utility tunnels in large
campus sites.
Ongoing
Work activity shall dictate. Prepare a
report if necessary to involve other
utilities.
Inspect and tighten all grounding (earthing)
and bonding connections.
Ongoing
Work activity shall dictate. Prepare a
report if necessary to involve other
utilities.
Pole inspections.
On-demand
Tagging unsafe conditions.
MH =
PB =
Maintenance hole
Pull box
OSP Design Reference Manual, 4th edition
12-8
© 2007 BICSI®
Chapter 12: Maintenance and Restoration
Emergency Restoration Procedures
Address Critical Elements
One of the more important parts of the maintenance plan is the section dealing with out-ofservice emergency recovery procedures.
Critical elements that an emergency recovery plan must address include:
© 2007 BICSI®
•
Identification and contact of essential personnel—During system outages, there must be
no delay in contacting key personnel who, in turn, must respond quickly and possess the
proper skill sets to repair the outages. These personnel must have predefined duties and
roles that are both understood and well practiced.
•
Accessing and obtaining materials—Materials set aside for emergency restoration should
be easily accessible and readily available to restoration teams. Sufficient quantities and
types of material required during an emergency must be stored and available for ready
access.
•
Troubleshooting procedures—Basic emergency troubleshooting procedures must be
documented in a clear and concise manner. Restoration teams must be familiar with the
necessary tasks and duties expected of them. A step-by-step format is recommended for
documenting these procedures.
•
Restoration tools—Emergency restoration tools and equipment should be set aside and
readily available for access by the restoration teams. Reserved equipment should be
checked on a regular basis to guarantee its readiness and proper functionality. Do not use
worn or obsolete equipment for emergencies. Do not use emergency equipment as a
substitute for routine use equipment. Even short-term use of emergency reserves for
normal operations with planned replacement in the near future must not be tolerated.
•
Circuits—Critical circuits that must be restored promptly must be documented as part of
the emergency restoration plan. Priority circuits should be clearly marked and identified.
These circuits are the first to be restored. The first goal is to return the OSP infrastructure
to operations in a staggered but prioritized manner. The secondary goal is to return the
system to normal operations and restore it as closely as possible to the original or
improved operational parameters when the outage or emergency occurred.
•
Test equipment—Emergency restoration test equipment should be set aside and readily
available for access by the restoration teams. Reserved equipment should be checked on
a regular basis to guarantee its readiness and verify current calibration as required.
•
Connections—Temporary grounding (earthing) and bonding connections are required
during emergency work operations to minimize service interruptions and ensure employee
safety.
12-9
OSP Design Reference Manual, 4th edition
Chapter 12: Maintenance and Restoration
Address Critical Elements, continued
The emergency restoration plan must identify and include procedures for permanent
restoration and repair. These procedures must provide detailed information showing and
explaining the steps necessary for restoring the system to normal operational parameters after
an emergency restoration operation has been completed. This may involve creating a plan for
systematically cutting over a cable section to a new replacement section. It is insufficient to
revert to the normal routine once the service has been restored—the system itself must be
returned to normal.
Temporary repairs cannot be left in a provisional status—they must be made permanent. One
problem with establishing priorities for the assignment of maintenance resources is that
service-affecting conditions normally take precedence over non-service-affecting conditions.
Once an out-of-service condition is fixed, it drops in priority even though the OSP condition is
not returned to its pre-trouble condition. The entire event must be treated as one, and the
permanent repair must be made before it is considered fixed.
While expensive to do, a trial run of the emergency restoration plan should be conducted
periodically to ensure it operates properly. Finding flaws in the plan during its execution under
abnormal conditions is not acceptable. The trial run should ensure that:
•
All parties know what they are expected to do.
•
Records are available and complete.
•
Materials, tools, and equipment are ready.
The emergency restoration plan must provide procedures and guidelines for documenting the
restoration that occurred, circuit reassignments that may have occurred, and long-term system
configuration after all permanent repairs have been completed.
Update the emergency restoration plan following the completion of the after-action report
(explaining in detail what caused the outage or emergency condition) and the
long- and short-term actions taken to repair the OSP infrastructure. The after-action report
must identify any OSP infrastructure documentation that must be revised and replaced. Most
importantly, the report must provide an analysis of the occurrence with recommended actions
and plans for preventing similar incidents in the future.
These reports must remain in an OSP infrastructure historical file for trend analysis, and
copies provided to other support regions to help prevent similar occurrences in other regions.
If similar incidents occur, the OSP infrastructure must be evaluated and possibly redesigned to
prevent future outages or problems.
Finally, any material or equipment resources that were expended in the restoration must be
replaced so the organization is ready to deal with any future system failures.
OSP Design Reference Manual, 4th edition
12-10
© 2007 BICSI®
Chapter 12: Maintenance and Restoration
Restoration Issues
Maintenance will keep OSP in service, but there are occasions when a system or facility
failure occurs. Customers expect that outages will be infrequent and of short duration. A plan
for addressing any outage must exist and must be understood and implemented by the
responsible parties (see Table 12.3).
Table 12.3
Emergency restoration issues
Description
Requirement
Note:
Infrastructure records
Ongoing, keep current information Maintain CAD files and send updates
to the field forces. Access provided to
the restoration forces on demand.
Work order activity marked
on the records
Current ongoing, keep current
information
All activity posted to the master. Access
provided to the restoration forces on
demand.
Facility records
Current ongoing, keep current
information
MACs updated daily. Access provided to
the restoration forces on demand.
On call information
Current ongoing, keep current
information
On call responsible party has the
necessary contact information at all
times.
All emergency agencies, police, Current ongoing, keep current
fire, medical information
information
MACs updated daily. Access provided
to the restoration forces on demand.
Contractor on call person
Current ongoing, keep current
information
Outside supply source list
Current ongoing, keep current
information
Visual inspection only unless cause for
braking seal.
Notification of critical users
in case of outage
As soon as possible
Estimated time of restoral to be provided
as soon as possible.
Placement of temporary air
supplies if required
As soon as possible
To protect the remainder of the plant
from further damage during the outage.
C A D = Computer-aided design
M A C = Move, add, or change
© 2007 BICSI®
12-11
OSP Design Reference Manual, 4th edition
Chapter 12: Maintenance and Restoration
Operations Support Centers
Operations support centers may be established within the operating territory of the coverage
area. Personnel and equipment are required to be available to respond in a quick and timely
manner to any type of maintenance request.
Maintaining a fully staffed operations support center for smaller operations (e.g., campuses) is
not financially feasible, and the necessary equipment and materials required to be kept in
inventory is not practical. An agreement with a qualified contract provider who has the
technical resources at their disposal is required. A qualified contractor who has ongoing
agreements with material suppliers who have the required inventory is a much more costeffective approach for rapid response requirements for any outages—either small or large.
Develop criteria for restoration requirements and practices and submit requests for
information (RFIs) to qualified providers to prepare bids to meet the service needs of the
owner. Smaller exchange operations (e.g., large campuses) can utilize the campus police or
other 24-hour entity having responsibility to provide the on call requirements for notification of
the on call management and the technicians.
A repair support site or operations support center requires a staff with necessary operational
skills. The staff must be trained and competent in the normal daily operations along with
having necessary skills for restoration of the system. Each staff member may not necessarily
have the same skill sets or capabilities, but the combined team must be capable of all aspects
of the restoration, maintenance, and operation of the system. The same individual skill
capabilities must exist in multiple personnel. As time permits, individuals should be trained in
the duties and responsibilities of other team members. Through cross-training, team members
are assured of having equal skill sets.
OSP Design Reference Manual, 4th edition
12-12
© 2007 BICSI®
Chapter 12: Maintenance and Restoration
Operations Support Centers, continued
Major repair support sites or operations support centers must have:
© 2007 BICSI®
•
Complete end-to-end and up-to-date documentation—The development and retention of
accurate records should be the first priority. Each support site must have a thorough and
complete documentation for the area for which it is responsible. In addition to documentation for its own area, each support site must have ready access to information for adjacent
service areas. At a minimum, documentation must include drawings, practices, and
procedures for all balanced twisted-pair and coaxial cabling, optical fiber strands, circuits,
and service requirements. Electronic copies of the network data are essential. Multiple
copies of documentation need to be maintained in updated versions at multiple locations
(e.g., engineering offices, operations center locations) to prevent the loss or destruction of
a single set from jeopardizing operations. The documentation must exist both on the
records and in the field. Stenciling, tagging, and other marking is mandatory when trying to
identify the particular facility that is in trouble. Offsite updated documentation back-up
files should be available for immediate access.
•
Basic troubleshooting capability—The staff must be able to resolve basic troubles by
employing simple troubleshooting techniques. These should include, but are not limited to,
optical fiber cuts, earth removal, circuit disruptions, equipment outages, and vandalism.
The operations center staff must be able to test, troubleshoot, and oversee the repair and
return of the system to service quickly and efficiently.
•
Easy access to next-level support—The staff involved in a given occurrence must be able
to reach the next level of problem support and trouble resolution quickly and easily. To
ensure a high reliability OSP infrastructure, personnel must be available on a 24/7 basis.
An on call plan must exist for the next tier. In addition to having an established and
approved plan, the maintenance staff must be well rehearsed in the procedures to the
point that it is second nature for them. Contact telephone numbers of key personnel must
be posted at all key locations.
•
Emergency restoration materials—Maintenance and repair equipment, test equipment,
repair materials, and other items routinely needed must be stored and available at strategic
locations. Included among these items are lengths of balanced twisted-pair, coaxial, and
optical fiber cable for emergency restoration in case of an earth removal, along with
necessary splice material. These can be maintained by a responsible party who is
contracted to provide the services and materials.
12-13
OSP Design Reference Manual, 4th edition
Chapter 12: Maintenance and Restoration
Operations Support Centers, continued
Operations Support Center Locations
The operations support center should be housed in a location that provides an effective
environment for coordinating the emergency restoration of the OSP infrastructure in case of
network outage or system emergency. The on call support centers should be established in
areas most likely to not sustain damage or failure.
A contingency plan should be available in case the OSP operations support center location is
damaged or rendered inoperable. These locations should have priority telephone lines available
both internally and for customer access. These sites must have tools, test equipment, and
restoration materials readily available, along with experienced emergency restoration crews.
Emergency restoration procedures must be documented, practiced, and well understood by all.
Some items that must be included in emergency plans are:
•
Notification procedures for crucial personnel, including contact telephone numbers.
•
Troubleshooting practices and procedures in the event of an incident. Key personnel must
have predetermined duties and responsibilities.
•
Detailed procedures for easy access of restoration materials that include where and how
these materials are stored and how to obtain them.
•
Details for ensuring that restoration equipment and test gear are always available and
operational and the teams are proficient in the use of the equipment. A system must exist
for the replenishment and replacement of any materials used for emergency purposes.
•
Information identifying critical balanced twisted-pairs, optical fibers, and priority circuits
for restoration. Restoration plans must be updated and maintained when circuit
assignments and changes occur. If the documentation available to restoration crews is not
updated, it is possible that actions taken by the team based on obsolete information may
compound the problems.
•
Methods and documented procedures to be used for OSP infrastructure restoration.
•
Plans and procedures for permanent repairs after the emergency situation has passed.
•
Plans for documenting the incident and preparing a report that analyzes the cause of the
incident, procedures followed to resolve the incident, and a vehicle for making recommendations for preventing similar events in the future.
•
Authority to authorize material and labor purchases for necessary repairs.
OSP Design Reference Manual, 4th edition
12-14
© 2007 BICSI®
Chapter 12: Maintenance and Restoration
Summary
In order for the client to consistently implement cable systems, including the supporting
infrastructure, standards must be developed and consistently adhered to as network
implementation goes forward. The quality of the planning, design, and construction of the OSP
network will become very apparent through the OSP maintenance and restoration records and
is essential for the survivability and reliability of the facilities. Establishing a routine
maintenance schedule for the network is necessary to support the network and the customers.
Unforeseen events cannot be forecast, but proper procedures and training can minimize the
impact on the organization’s network. It is imperative to budget for possible outages. With
good planning and procedures, the funding will be sufficient to service the network. As
discussed in previous chapters, these items will affect the performance and longevity and
reduce the maintenance costs for the life of the OSP infrastructure.
© 2007 BICSI®
12-15
OSP Design Reference Manual, 4th edition
Chapter 13
Special Design
Considerations
Chapter 13 describes air pressure system parts, including
air pipe, air dryer, manifold assembly, automatic shutoff
valve, pressure transducer unit, and cable pressure
monitoring system. It also explains the design
considerations, the concept of overbuild and makeready
design, and the process of extending a cable vault.
Chapter 13: Special Design Considerations
Table of Contents
Air Pressure Systems ....................................................................... 13-1
Introduction .............................................................................................. 13-1
Air Feeder Pipe .......................................................................................... 13-2
Air Dryers ................................................................................................. 13-3
Manifold Assembly ...................................................................................... 13-4
Automatic Shutoff Valve ............................................................................. 13-4
Pressure Transducer Unit ............................................................................ 13-5
Cable Pressure Monitoring Systems ............................................................... 13-7
Standard Operating Environment .................................................................. 13-8
Design Considerations ............................................................................... 13-10
Air Pipe Manifold Spacing ...................................................................... 13-10
Optimum Air Usage (OAU) Calculations ................................................... 13-10
Design Stick Maps ............................................................................... 13-11
Buried Design ..................................................................................... 13-12
Aerial Design ...................................................................................... 13-13
Device Logs ....................................................................................... 13-14
Buffering Information ........................................................................... 13-14
Overbuild on Existing Aerial Facilities .............................................. 13-15
Introduction ............................................................................................ 13-15
Design Considerations ............................................................................... 13-15
Pole Ownership ........................................................................................ 13-16
Makeready Design .................................................................................... 13-16
Makeready Forms and Procedures .......................................................... 13-18
Makeready Overview for Underground Plant ............................................. 13-20
Overbuild on Existing Underground Pathways ................................. 13-22
Introduction ............................................................................................ 13-22
Design Considerations ............................................................................... 13-22
Extending a Cable Vault .................................................................. 13-24
Introduction ............................................................................................ 13-24
Design Considerations ............................................................................... 13-24
References ..................................................................................... 13-25
© 2007 BICSI®
13-i
OSP Design Reference Manual, 4th edition
Chapter 13: Special Design Considerations
Figures
Figure 13.1
Air dryer ................................................................................... 13-3
Figure 13.2
Manifold assembly and shutoff valve .............................................. 13-4
Figure 13.3
Transducer housing mounted on framing channels ............................ 13-5
Figure 13.4
Example of pressure transducer installation ..................................... 13-6
Figure 13.5
Flow transducer ......................................................................... 13-7
Figure 13.6
Typical air pressure schematic design ............................................ 13-9
Figure 13.7
Typical schematic of air pressure system. .................................... 13-11
Figure 13.8
Example of buried cable leaving underground ................................. 13-12
Figure 13.9
Underground to aerial interface ................................................... 13-13
Figure 13.10
Buffering arrangement at a splice ................................................ 13-14
Figure 13.11
Typical pole space allocations .................................................... 13-17
Tables
Table 13.1
Typical minimum pressure ............................................................ 13-8
OSP Design Reference Manual, 4th edition
13-ii
© 2007 BICSI®
Chapter 13: Special Design Considerations
Air Pressure Systems
Introduction
Air pressure systems are used to protect air core cables from water and other liquid
contaminants that could be introduced through cable sheath cracks, breaks, or leaky splice
closures. They subject the inner core of the cable under the outer sheath to a dry, or low
water content, constant pressure air source and may extend the life of a cable plant. Although
generally used in underground conduit systems, air pressure systems also may be used in
direct-buried and aerial plants.
Air pressure systems shall be maintained to ensure service integrity. Extensions on existing
systems may appear to be cost-efficient; however, new (initial) outside plant (OSP) designs
that require the use of air pressure systems should be avoided because they require substantial
maintenance. In addition, alternate and more reliable plant designs are available.
The evolution of technology has provided for more effective cable construction. The sheath
has higher integrity, and the core of the cable contains materials that are resistant to water
penetration. Consequently, many owners of air core cable that is protected by air pressure
systems are removing that type of cable as they provide route relief or facility upgrades. The
references section of this chapter provides a list of industry standards that offer suggestions
and information for customers maintaining existing air pressure systems. These standards
typically require that all air core cables placed in subsurface pathways be pressurized. A
recommendation for venting of aerial cables is included.
Generally, new OSP cabling systems are designed to eliminate the need for air pressure
systems. The number and extent of legacy air systems are diminishing. The cost of continually
investing in monitoring systems and air pressure equipment and deploying technicians to
maintain target pressure levels makes the expansion of networks that use air pressure
unattractive. Still, the amount of air core cable that is in service—whether aerial, underground,
or buried—represents a sizable capital investment. An effective program that uses air
pressure to minimize troubles and to protect an investment still can return value during the
remaining useful life of the cabling system.
Air pressure systems are still commonly used for radio frequency (RF) waveguide in
connecting antennas to radio transmitters. For more information, see the BICSI Wireless
Design Reference Manual (WDRM).
A method using a pipe system for cable pressurization is essentially a configuration that
applies air pressure through an air pipe to cables. Air pressure also is supplied at selected
maintenance holes (MHs) or handholes (HHs) along an underground cable route. This is
accomplished by connecting individual cables to a parallel air feeder pipe that carries
pressurized dry air from an air source. The flow resistance of the pipe is low with typical
pressure drops of 14 to 21 kilopascals (kPa [2 to 3 pound-force per square inch (psi)]) over
several kilometers (km [miles (mi)]) (e.g., 5 km [3.1 mi]) from the sources.
© 2007 BICSI®
13-1
OSP Design Reference Manual, 4th edition
Chapter 13: Special Design Considerations
Introduction, continued
The components of a complete air pressure system vary with configuration and design
requirements. The assembly units for a typical system are:
•
Air pipe (i.e., feeder, distribution).
•
Air dryer (i.e., compressor, dehydrator).
•
Manifold assembly.
•
Automatic shutoff valve.
•
Pressure transducer unit.
•
Cable pressure monitoring system.
Air Feeder Pipe
An air feeder pipe is used as the basic dry air artery in pipe systems. Typically, the pipe:
•
Is aluminum lined.
•
Is constructed of black polyethylene.
•
Has an approximate inside diameter (ID) of 15.2 millimeters (mm [0.6 inches (in)]).
•
Has an approximate outside diameter (OD) of 19 mm (0.75 in).
•
Weighs approximately 3.6 kilograms (kg [8 pounds (lb)]) per 30.5 meters (m [100 feet
(ft)]). Shipped from the factory under pressure, air feeder pipe is typically available in reel
lengths of 600 to 1070 m (2000 to 3510 ft). It can be hand formed to a 127 mm (5 in)
radius for installation. The maximum allowable pulling stress for the pipe is 68 kg (150 lb).
IMPORTANT:
Overstressing can shear the bond between the aluminum
and the polyethylene.
Additionally, an air feeder pipe with mechanical protection for additional strength is available in
the same internal dimensions as the earlier mentioned pipe. This pipe is used in underground or
direct-buried applications for added protection against rodents.
OSP Design Reference Manual, 4th edition
13-2
© 2007 BICSI®
Chapter 13: Special Design Considerations
Air Dryers
Air dryers are the initial dry air source (see Figure 13.1). They generate the required air
pressure that is fed through the manifold system and into the cables. Air dryers also can be
placed in remote field locations. These remote dryers are designed to extend air pressure to
the points in the system where the main unit cannot sustain pressure requirements.
A dual dryer system at the main cross-connect (MC [campus distributor (CD)]) ensures air
pressure to the cables. An automatic transfer switch ensures that the idle dryer activates if the
on-line dryer fails.
Figure 13.1
Air dryer
Master
stop-start
switch
Lifting lug
Refrigeration
thermostat
Heat exchanger
temperature gauge
High-pressure
gauge
Output pressure
regulator
Gel-fill plug
Humidity-sensing
element
Main gel tower
Reserve
gel tower
Gel drain plug
Air compressor
Refrigeration
compressor
Fan guard
Condensate tank
drain valve
Damper
(in stored position)
Heater guard
NOTE:
© 2007 BICSI®
The air dryer shown is representative of units that could be in the field. Check with
manufacturers for the latest products.
13-3
OSP Design Reference Manual, 4th edition
Chapter 13: Special Design Considerations
Manifold Assembly
A manifold assembly is a unit that facilitates the connection between the air dryer and OSP
cables. A manifold is usually equipped with an automatic shutoff valve and could have a
number of ports for attaching air pipes to cables. One of the more commonly used units has
five ports, threaded pipe connections, and individual valves to measure pressure to each cable.
Automatic Shutoff Valve
An automatic shutoff valve is connected in the dry air line between the air feeder pipe and the
manifold assembly at each manifold location. If there is a pipe failure, the shutoff valve
protects underground cables from abnormal air loss by closing the air connection to the
manifold. The valve closes if there is a condition causing reverse airflow. When the pipe
pressure builds up to 2 kPa (0.29 psi) above the manifold or cable pressure, the valve reopens.
If the air pressure system and manifold assembly are in an MH, it is necessary to bond all
manifold assembly units to a permanent MH ground (earth).
All aerial assembly units shall be grounded (earthed). All aerial feeder pipes shall be bonded at
the first, the last, and every fifth pole (see Figure 13.2).
Figure 13.2
Manifold assembly and shutoff valve
Valve for testing
pipe pressure
Manifold assembly
Valve for testing
manifold pressure
Valve for
testing
individual
cable
pressure
Connection
for tubing from
pipe line
Automatic
shutoff valve
9.5 mm (3/8 in)
Threaded pipe
plastic tubing to
individual cable
in =
mm =
Inch
Millimeter
OSP Design Reference Manual, 4th edition
13-4
© 2007 BICSI®
Chapter 13: Special Design Considerations
Pressure Transducer Unit
Activated by air pressure, a pressure transducer unit is a stepped switch instrument that
converts cable pressure to electrical resistance. The transducer measures pressure from
0 to 65 kPa (0 to 9.4 psi) in 3.4 kPa (0.5 psi) increments, with corresponding resistance values
from 100 000 to 3.82 million ohms ( Ω ).
The unit connects from the electrical side of the housing via cable pairs and is spliced into one
of the cables feeding back to the monitoring station. It transmits all data regarding airflow
logistics at that point back to a monitoring panel.
A cable pressure monitoring system can be accessed from an administration monitoring
location (see Figures 13.3 and 13.4).
Figure 13.3
Transducer housing mounted on framing channels
© 2007 BICSI®
13-5
OSP Design Reference Manual, 4th edition
Chapter 13: Special Design Considerations
Pressure Transducer Unit, continued
Figure 13.4
Example of pressure transducer installation
Pressure
transducer
housings
Plastic tubing to
cable or pipe
Framing channel
Underground
pressure
transducer
Transducer
housing
stub cables
Junction box
Pressure
testing
valve
Junction
box stub
cable
Framing channel
Stub cable fitting
Splice closure
OSP Design Reference Manual, 4th edition
13-6
© 2007 BICSI®
Chapter 13: Special Design Considerations
Cable Pressure Monitoring Systems
Cable pressure monitoring systems have evolved significantly over the years. Early versions
used on/off contacts that could be set to alarm once a certain pressure threshold was reached.
A triggered alarm indicated failure to hold the specified pressure. The alarm provided only an
on/off indicator and did not report about the dynamics of the system (i.e., whether there was a
slow leak or an imminent failure).
Current models offer a microprocessor-based device that continuously monitors the airflow at
meter panels and pipe alarms at the monitoring station. They provide surveillance of total
airflow from the panels or manifolds to the pressurized cable network, including air pipes.
Measuring airflow is the best indicator of a pressurization system’s condition. Properly
analyzing changes in air consumption aids in identifying the most damaging system leaks and
provides the basis for prioritizing both cable and pressure system maintenance.
Airflow can be monitored for multiple pipe alarms as a stand-alone system. This can be
reported to a remote monitoring location using signal wires within the cable sheath.
A flow transducer (see Figure 13.5) provides precise flow measurements in both standard
cubic meters per hour (SCMH [m3/h (standard cubic feet per hour [SCFH (ft3/h)])]) and
standard cubic meters per day (SCMD [m3/d (standard cubic feet per day [SCFD (ft3/d)])]).
Figure 13.5
Flow transducer
Channel
Channel
Flow
transducer
Serial
port
Flow card number
Flow card number
© 2007 BICSI®
13-7
OSP Design Reference Manual, 4th edition
Chapter 13: Special Design Considerations
Standard Operating Environment
Although every company adopts their own standards for designing, supporting, and maintaining
air pressure systems, a company or a designer may want to review what larger companies
use as a standard operating environment for their air pressure systems. The values in
Table 13.1 represent typical minimum pressure.
Table 13.1
Typical minimum pressure
The typical minimum pressure for…
Is…
Air pipes
52 kPa (7.5 psi)
Underground cable
34 kPa (5 psi)
Direct-buried cable
21 kPa (3 psi)
Aerial cable
14 kPa (2 psi)
kPa = Kilopascal
psi = Pound-force per square inch
The typical flow per sheath kilometer is 0.025 m3/h or 0.60 m3/d (0.88 ft3/h or 21.19 ft3/d).
(Flow per sheath is 0.035 m3/h [1.24 ft3 /h] or 0.85 m3/h [30.02 ft3/d].)
In addition to the above standards, all:
•
Main entrance facility (EF) airflows (e.g., pipe panels, distribution panels) should be
monitored with a properly sized flow transducer.
•
Air dryers should be monitored remotely 24 hours a day, 7 days a week, for proper
operation.
•
Main EFs with dual air dryers must have an alternator installed, and both dryers must be
properly alarmed.
•
Underground air core cables should be monitored at properly spaced intervals the entire
length of the cable run.
•
Air pipes should be monitored for pressure at all end points.
OSP Design Reference Manual, 4th edition
13-8
© 2007 BICSI®
Chapter 13: Special Design Considerations
Standard Operating Environment, continued
Figure 13.6 provides a typical air pressure schematic design.
Figure 13.6
Typical air pressure schematic design
Entrance facility
01 CA
02 CA
03 CA
04 CA
05 CA
CA
© 2007 BICSI®
Manifold
Flow transducer
Pressure transducer
Cables
End cables
End pipe pressure transducer
13-9
OSP Design Reference Manual, 4th edition
Chapter 13: Special Design Considerations
Design Considerations
Air Pipe Manifold Spacing
Air pipe manifolds are installed in the field as a means of splitting the air source from the air
pipe to serve multiple cables. The distance for separating manifolds has increased from 600 m
to 1830 m (2000 ft to 6000 ft). When designing a new air pressure system, consider a
common distance for all current and future spacing requirements. Evaluate this process when
considering MH locations and spacing.
Manifolds and monitoring devices should not be placed in MHs containing load apparatus or
repeater housings or in congested MHs. These locations experience frequent splicing activity
and often lack space required for installation and future maintenance activity.
Optimum Air Usage (OAU) Calculations
Optimum air usage (OAU) calculations are used to determine air pipe and air dryer
requirements and the degree of protection an existing pressure system is providing. The
calculations are based on the standard allowable consumption of a sheath kilometer of cabling
that is 0.025 m3/h (0.88 ft3/hr). Multiply the number of sheath kilometers by 0.025 m3/h (0.88
ft3/h).
NOTE:
A sheath mile of cabling is 1.25 ft3/h and the optimum air usage is obtained by
multiplying the total number of sheath miles by 1.25 ft3/h.
OSP Design Reference Manual, 4th edition
13-10
© 2007 BICSI®
Chapter 13: Special Design Considerations
Design Considerations, continued
Design Stick Maps
Stick maps show the complete layout of a pressure system in a simple stick format and
include OAU target levels and device locations (see Figure 13.7).
Figure 13.7
Typical schematic of air pressure system
Telecommunications equipment room
Cables
Air
dryer
Low
pressure
Cables
Meter
panel
MF
MF
Monitoring points
Pipe route B
UG
cables
V
Approx.
Approx.
900 m
900 m
(3000 ft) (3000 ft)
V
Approx.
Approx.
900 m
900 m
(3000 ft) (3000 ft)
PP B
PP A
Approximately
1830 m (6000 ft)
ft
m
MF
PP
UG
V
=
=
=
=
=
=
MF
MF
Approximately
1830 m (6000 ft)
MF
Approximately
1830 m (6000 ft)
Foot
Meter
Pipe manifold. Connected to each designated cable in maintenance hole.
Air feeder pipe. The letter following the symbol PP is the pipe route designation.
Underground.
High valve. Pressure testing valves located in neck of maintenance hole and
connected with plastic tubing to each designated cable.
Air pressure design drawings should show the pipe routes, assigned conduits, locations of
manifold, and both flow and pressure transducers.
© 2007 BICSI®
13-11
OSP Design Reference Manual, 4th edition
Chapter 13: Special Design Considerations
Design Considerations, continued
Buried Design
When a buried cable leaves the underground system (see Figure 13.8) within 450 m (1476 ft)
of an underground manifold, the next transducer should be installed on the buried cable at the
normal spacing interval, or approximately 900 m (3000 ft) from the underground manifold. It is
desirable to place a bypass at the point where the cable leaves the underground system to
install a pressure controller (adjusted to maintain a minimum of 21 kPa [3 psi] at the cable
end).
Figure 13.8
Example of buried cable leaving underground
Field
Buried cable
Air pipe
MH
MC
(CD)
Field
Bypass tube and
pressure controller
MC
(CD)
Field
Pressure plug
MC (CD) = Main cross-connect (campus distributor)
MH = Maintenance hole
OSP Design Reference Manual, 4th edition
13-12
© 2007 BICSI®
Chapter 13: Special Design Considerations
Design Considerations, continued
Aerial Design
When an air core cable transitions from underground to aerial cable, the pressure transducer
spacing should be treated as a continuation of the underground system. At the point the cable
leaves the underground, a bypass arrangement with a pressure controller set from 14 kPa
(2 psi) to 28 kPa (4 psi) is installed. The objective is to maintain a pressure of 14 kPa (2 psi) at
the end of the aerial cable (see Figure 13.9).
Figure 13.9
Underground to aerial interface
Pressure plug, bypass
tube, and pressure
controller placed
under U-guard
MC
(CD)
Field
Cable
MC (CD) = Main cross-connect (campus distributor)
© 2007 BICSI®
13-13
OSP Design Reference Manual, 4th edition
Chapter 13: Special Design Considerations
Design Considerations, continued
Device Logs
A device log is a recordkeeping tool that cross-identifies the air pressure system or device to
the cable and the cable count it feeds.
Buffering Information
Cable buffering is a means of supporting the air pressure at cable sheath openings during
splicing activities. This is achieved by introducing supplemental air sources (e.g., nitrogen
cylinders, truck-mounted compressors). By adding this supplemental source to the cable
sheath, the open splice does not act as a zero leak or endanger the pressure network and its
surrounding cables. Multiple methods and configurations can be used to buffer a cable sheath
break adequately. The key is to ensure that cable pressure is maintained during splicing or
repair operations.
Figure 13.10 shows an example of cable buffering. A supplemental air source is introduced to
the field side of the cable opening and, in combination with the air supplied from the MC (CD)
side, positive air pressure is maintained.
IMPORTANT:
Nitrogen gas is used to buffer the pressure system because nitrogen is a
noncombustible gas.
Figure 13.10
Buffering arrangement at a splice
Air pipe
Manifold
Open splice
Plug
60 m
(197 ft)
ft = Foot
m = Meter
OSP Design Reference Manual, 4th edition
13-14
© 2007 BICSI®
Chapter 13: Special Design Considerations
Overbuild on Existing Aerial Facilities
Introduction
An overbuild design generally is utilized when a company intends to build new aerial plant on
strand and cable they already own. Typically, an OSP design engineer designs a plant for 10 or
more years of service growth. When the aerial cable facility is about to exhaust the copper
cable pairs or optical strands, an additional aerial cable may be the choice for supplementing
the plant.
An overbuild also can be used when:
•
The aerial route is attractive as a route to another area
•
Optical fiber or coaxial cable is placed on the existing aerial route to upgrade the type of
service or technology that the original cable plant cannot support.
•
An aerial plant is added to a pole that has other communications vendors already
attached.
When these overbuilds are identified, the OSP engineer has several design issues to consider
before the additional cabling is added to the pole line.
Design Considerations
The OSP aerial design engineer has to know who owns the poles to which the existing aerial
plant is attached. If the pole line is owned by others, attachment contracts, attachment fees,
and fees to upgrade the poles may be required. A contract with the pole owner has to be
reviewed so that everyone’s responsibilities are understood.
Poles are identified by their owners with a tag that lists the owner and the pole and route
number. When manufactured, the pole has a class identification system and length embedded
in the pole so that the engineer knows the amount of weight the pole will support. All of this
information, including the length between pole spans, is used by the engineer and the pole
owner’s engineer to determine whether an overbuild is possible with the existing poles.
An overbuild will increase the weight on the poles, support strand, and hardware. Considerations for the weight can include ice loading in areas where winter weather can create this
hazard. The design engineer must know the weight of the cable being placed, the lashing wire,
and the existing strand and cable. The weight of the hardware, cross-connect boxes, and
splice closures also must be considered.
When the OSP design engineer has created an engineering drawing with all of the information,
this is included with a pole attachment request to the pole owner. The pole owner’s engineer
will meet with the OSP design engineer at the overbuild route to ensure the accuracy of the
information provided. The pole owner’s design engineer then will perform calculations to
ensure that the overbuild meets the codes and regulations for the type of pole line that is
currently built.
© 2007 BICSI®
13-15
OSP Design Reference Manual, 4th edition
Chapter 13: Special Design Considerations
Pole Ownership
An overbuild request to the pole owner should be submitted months in advance of the required
overbuild. The design engineer’s request can be among several for the pole owner to consider
throughout the whole plant. If the pole owner determines that a pole or several poles will have
to be replaced, it could take months before the work can be completed by the pole owner.
In some instances, the aerial plant may be sharing the pole with multiple communication
vendors. It is not uncommon for a pole line within a city to have three or more vendors
attached to the poles. The pole owner also must consider the weight factors of those facilities.
Typically, the vendor who places the pole line in jeopardy with the codes and regulations is the
responsible party for paying the pole owner to replace the poles. This is an expensive
undertaking by the pole owner, who will pass those costs to the offending vendor. This process
sometimes is referred to as makeready. In some cases, it may be less expensive to consider
making a transition to underground for short distances and then back to aerial.
The pole owner will notify all of the vendors attached to the pole when a pole has to be
replaced. Some cities have a color-coded cable tagging system so that everyone can easily
identify ownership of the plant facilities. It is up to the individual plant owners to transfer their
strand, hardware, and cable facilities to the new poles after construction.
An overbuild design is not difficult, but performing the weight load calculations takes a lot of
time. The OSP design engineer and the pole owner’s engineer always must consider safety
when an overbuild is considered. Electrical shock, pole breaking, and strand and cable
dropping between the poles are some of the dangerous hazards that a properly designed
overbuild avoids.
Makeready Design
The design work required to specify the attachments of new aerial plant onto existing poles
sometimes may be done as a separate project. In such case, a utility owns the pole and the
designer determines sufficient space and specifies construction work for attachments.
Whenever sufficient space is not available, the designer would produce specified drawings to
propose rearrangements, replacements, or additional poles. The generic term for this process
is makeready design.
Calculations will be provided to verify and secure separations and clearances required in
attaching to existing pole lines. These calculations require company-by-company comparisons
and do not reflect the only space allocations provided by pole owners.
OSP Design Reference Manual, 4th edition
13-16
© 2007 BICSI®
Chapter 13: Special Design Considerations
Makeready Design, continued
Ownership must be determined first for pole lines and various utilities attached so that their
agreement to the attachment is secured. Sometimes the ownership will be marked clearly on
the poles, and other times it may require a joint field survey with the utility companies. Once
the ownership is determined, the next step is to determine adequate space to attach.
Communications cables should be adequately separated based on applicable local codes and
the utility owner’s needs. The pole owners also may provide typical space allocations.
Figure 13.11 is an overview of one method of provisioning space for multiple users for
different power company space requirements on a single pole at minimum required heights.
Figure 13.11
Typical pole space allocations
Power
based on remaining
space left on pole
Negotiated
space
Communications
generally
1.2 m (4 ft)
0.91 m
(3 ft)
5.5 m
(18 ft)
Clearance
Generally
5.5 m (18 ft)
Depth
generally
1.98 m
(6.5 ft)
Pole depth
based on
size of pole
1.83 m
(6 ft)
10.7 m (35 ft)
Pole
12 m (40 ft)
Pole
16.8 m (55 ft)
Pole
15 m (50 ft)
Pole
13.7 m (45 ft)
Pole
ft = Foot
m = Meter
NOTE:
Generally, negotiated requirements are adjusted with the power company’s space.
It is important to keep in mind that each joint-use agreement is different and will be based on
what the pole owners and other concerned parties have included in the agreements. When
additional attachment heights or separations are required, the designer and the pole owner will
determine where appropriated space allows them to attach and what dictates their
responsibilities of costs for rearrangements, replacements, or increases in pole sizes.
The designer generally can determine how much makeready work will be required if a presurvey with the pole owners is conducted first to determine agreements, costs, and flexibility
of the owners. When considering utilizing a pole line owned by others, the owners are entitled
to determine how, how much, and when anyone else will be allowed to attach.
The other consideration is a project timeline. If the project is required by a certain schedule, it
will be important to determine whether the schedule can be accomplished within the pole
owner’s workloads.
© 2007 BICSI®
13-17
OSP Design Reference Manual, 4th edition
Chapter 13: Special Design Considerations
Makeready Design, continued
Makeready should go through the following process:
•
Completing a field survey and identifying the pole owners and proposed locations for
attachments
•
Identifying the owners of all attached plant
•
Scheduling a pre-survey with the owners and other attached utilities
•
Conducting the pre-survey and identifying the costs, requirements, scheduling, and rightof-way (R/W) needs
•
Creating construction drawings with all proposals
•
Filling out all joint-use requests and billing forms and noting any special arrangements
required
•
Sending out copies to all associated parties for final review
•
Obtaining authorizations and approvals to commence work
•
Issuing the drawings to construction and schedule
Makeready Forms and Procedures
Forms and procedures vary from owner to owner. The designer must ascertain all forms and
agreements before beginning the field survey to ensure that the design takes all of the
requirements into consideration.
Scenarios included in agreements can be helpful to decide what work or billing is to be
assigned. A sample agreement based on U.S. standards between a power company and a
telephone company with scenarios as described below. In this example, the standard pole is
12 m (40 ft) class 5:
•
The standard space on a joint-use pole is reserved space for the exclusive use of each
company.
•
Attachments of each company’s facilities shall be confined to their reserved space.
Certain power company attachments may be permitted within the reserved space
(e.g., grounded light bracket, vertical power risers).
•
All apparatuses (e.g., transformers, capacitor banks), cable sags, and drip loops shall be
confined with the reserved space.
•
Before any physical attachments are made by third-party licensees (e.g., community
antenna television [CATV], governmental agencies) within the reserved space of either
company, approval must be obtained from the company owning the reserved space.
OSP Design Reference Manual, 4th edition
13-18
© 2007 BICSI®
Chapter 13: Special Design Considerations
Makeready Design, continued
In this scenario, the joint-use pole space apportionments on 12 m (40 ft) poles will be 1.98 m
(6.5 ft) in the ground. Any deviations in pole setting depth will have a direct impact on the
following location dimensions:
•
The company standard space allocation is the uppermost 1.83 m (6 ft) of the pole located
from 8.4 m to 10.2 m (27.5 ft to 33.5 ft) above the ground.
•
The company standard space allocation is a 1.2 m (4 ft) space located from 5.5 m to
6.7 m (18 ft to 22 ft) above the ground.
•
Of the unallocated space (1.7 m [5.5 ft]) between 6.7 m and 8.4 m (22 ft and 27.5 ft)
above the ground, 1016 mm (40 in) is required for clearances between the lowest power
attachment and attachments of communications facilities. This leaves approximately 0.6 m
(2 ft) for further allocation between the power company and others. If not required by
either company, this space may be used for third-party licensee attachments (e.g., CATV,
governmental agencies).
•
To establish a fair allocation of this remaining space in circumstances where either or both
the power company and telephone company may need more than their standard space, it
is agreed that half of the aforementioned 0.6 m (2 ft) is available to the power company
and half is available to the telephone company for current or future reserved use. This
establishes a space entitlement of 2.1 m (7 ft) for the power company (8.1 m and 10.2 m
[26.5 ft to 33.5 ft]) and 1.52 m (5 ft) for the telephone company (5.5 m to 7 m [18 ft to
23 ft]).
The preceding space appointments are the basis for the following guidelines:
© 2007 BICSI®
•
If the telephone company needs to attach as high as 7 m (23 ft) and the power company
requires more than 2.1 m (7 ft) of space from the top of the pole, the power company
shall bear the entire cost of providing the extra pole height, including the telephone
company’s transfer costs.
•
If the power company needs the full 2.1 m (7 ft) of the pole (attachment height of 8.1 m
[26.5 ft]) and the power company needs to attach above 7 m (23 ft), the telephone
company shall bear the entire cost of providing the extra pole height, including the power
company’s transfer costs.
•
If the power company needs more than 2.1 m (7 ft) of the pole and the telephone
company needs to attach higher than 7 m (23 ft), all costs associated with providing the
extra pole height shall be shared equally. All rearrangement costs shall be the responsibility of the company owning the attachment.
•
If the power company needs to attach higher than 2.1 m (7 ft) and the telephone company
can attach below 7 m (23 ft), the power company may use the additional space without
changing out the pole.
•
If the power company needs to attach higher than 7 m (23 ft) and the power company
can stay within their normal 1.83 m (6 ft [8.4 m (27.5 ft) above grade]), the telephone
company may use the additional space without changing out the pole.
13-19
OSP Design Reference Manual, 4th edition
Chapter 13: Special Design Considerations
Makeready Design, continued
•
Any time the power company anticipates using more than 2.1 m (7 ft) of the pole or any
time the telephone company anticipates attaching above 7 m (23 ft), the engineer
anticipating such use must advise the engineer of the other company and obtain that
engineer’s written approval for such use. This written approval should be retained by the
company requesting the additional space to avoid future disputes.
•
Once an attachment is made by either company in their own unallocated space
entitlement (0.3 m [1 ft]), that attachment will be considered permanent.
•
Once an approved attachment is made by either company in the unallocated space
entitlement (0.3 m [1 ft]) of the other company, that additional space shall be considered
part of the standard space of the company making the attachment.
•
Any attachments made by either company in such a manner that, when combined, the
code clearance requirements prevent the other company’s full utilization of their standard
space (power company 1.83 m [6 ft], telephone company 1.2 m [4 ft]) will be considered
temporary. Such attachments must be relocated at the attachment owner’s expense if the
company owning the standard space requires full use of their space.
•
When third-party licensees must be accommodated on a joint-use pole, they will be
responsible for paying all makeready costs. This includes pole change outs and transfer
costs of both joint users if either or both need but cannot use all of their space entitlement
because of present or future licensee attachment requirements.
•
If either the telephone company or the power company declines joint use or does not
reserve space when a pole is established but later requests joint use, all of the pole
owner’s costs necessary to accommodate the joint user will be borne by the latter.
All makeready projects are unique, and a process is necessary to help the designer determine
whether costs associated with attachments are feasible compared with alternative methods.
Makeready Overview for Underground Plant
Makeready work in underground plants is very different from aerial plants. Only employees of
the controlling utility are allowed to enter the underground MHs. Visits must be coordinated
with the owner and arrangements must be made to secure a craftsman and equipment
necessary for the visit.
Underground plants can be very dangerous environments due to explosive and displacement
gases. Persons have been seriously injured or killed because they did not observe established
safety precautions and procedures.
OSP Design Reference Manual, 4th edition
13-20
© 2007 BICSI®
Chapter 13: Special Design Considerations
Makeready Design, continued
MH field visit requirements include the following minimum procedures before entering:
•
A test for explosive gas must be performed before opening the lid.
•
Water must be pumped out.
•
Ventilation must be performed for a minimum time based on volume to remove
displacement gases. Explosive gas detection will result in no visit and immediate special
treatment by the utility. Oxygen displacement gases (e.g., nitrogen) are a silent killer and
can be treated only by proper ventilation methods.
•
Special nonexplosive lighting must be used in an MH.
•
The utility probably will not provide drawings of their MH, so the requesting inspector
should prepare drawings suitable for placing operations and as-built prints. Cameras and
flashlights are not allowed because of possible spark or arcing.
•
At a minimum, overboots should be worn because of mud, silt, and water that may be
present.
The use of a utility’s underground plant can be very expensive in both the short and long term.
MHs must be preinspected for duct and racking space. The utility field engineer or
representative will prepare billing estimates for yearly leasing of duct space as well as billing
for the makeready inspection and any other makeready rearrangements necessary to
accommodate the additional cable. The owner also has the right to require that placement
operations be performed by one of their approved contractors who have the safety training
and equipment for working in underground environments without damaging the existing plant.
The utility will bill for any damage to their underground infrastructure, plant, or supporting
apparatus (e.g., air pressure pipes and devices).
When inspecting and using underground plant, extreme caution is advised. Generally, these
types of facilities do not have adequately equipped and trained maintenance crews to properly
test and vent MHs. In addition, this type of plant may contain electrical hazards from cables
that are not properly prepared or have been improperly installed. In some cases, these
facilities also may contain gas pipes that make them especially hazardous. MHs tend to act as
collection points for all types of gases, including minor leaks in gas pipes. In many cases,
underground plant also includes insect and other wildlife hazards.
© 2007 BICSI®
13-21
OSP Design Reference Manual, 4th edition
Chapter 13: Special Design Considerations
Overbuild on Existing Underground Pathways
Introduction
The term overbuilding as it relates to this section is defined as the addition of conduit to an
existing underground MH and duct system.
Existing underground pathways (e.g., cables installed in a conduit system) may need
overbuilding for several reasons:
•
The existing underground pathway is full of in-use or abandoned cables that cannot be
removed or overidden.
•
One or more ducts are collapsed between MHs.
•
New cable installation requirements call for additional duct space.
Design Considerations
The designer should consider overbuild actions if any of the conditions discussed previously
apply.
Installing a complete underground system can be very costly, which is why many designers
choose to overbuild an existing underground pathway rather than replace the entire system.
Some of the key questions that must be considered when designing an underground pathway
that will be overbuilt include:
•
Is there enough room in the existing MH to support additional conduit and cables?
•
Are there any obstructions or utilities along the current pathway?
•
Are there any special security considerations for the pathway?
•
Has enough labor been estimated for hand digging around existing MHs and utilities?
•
Will an MH need to be upgraded with racks and termination hardware to support
additional cables?
•
Will the underground pathway cross any roads or parking lots? If so, concrete casing is
recommended at those locations.
•
Can adequate placement depths be achieved to protect the new ducts from damage?
OSP Design Reference Manual, 4th edition
13-22
© 2007 BICSI®
Chapter 13: Special Design Considerations
Design Considerations, continued
Following are some best practice recommendations for designing an underground pathway
that is an overbuild:
© 2007 BICSI®
•
Whenever possible, design the route a minimum of 1.2 m (4 ft) away from existing
systems. This will allow machine excavation for the most of the route.
•
Terminate conduit at the lowest available point in the window in the MH. This will allow
for future growth.
•
When possible, place a spare duct for future requirements.
•
If the MH does not have a center rack, terminate conduit on either side rather than in the
middle for easier racking of cables.
•
Use proper separation and barriers as required where crossing existing utilities.
•
Place warning tape 152 mm to 305 mm (6 in to 12 in) below finished grade.
•
Install conduit with a tracer wire or wire manufactured into conduit when installing an alldielectric optical fiber cable in an underground pathway.
13-23
OSP Design Reference Manual, 4th edition
Chapter 13: Special Design Considerations
Extending a Cable Vault
Introduction
A cable vault is a telecommunications space, typically subterranean, located within or between
buildings and used for distributing, splicing, and terminating cables.
The expansion of a telecommunications cabling plant can create space limitation problems at
the cable vaults and telephone switching central office location. It is very costly to build a new
telephone switching central office and cable vault system to support new infrastructure
requirements.
Design Considerations
It is very expensive to relocate a telephone switch and cable plant to a new location. To save
time and money, many engineers and customers choose to extend the length and sometimes
width of an existing cable vault to support the new cable plant requirements.
Some key questions that must be considered when designing a cable vault extension include:
•
Will any utilities obstruct the extension of the new cable vault?
•
Will the cable vault extension be precast or poured construction?
•
Has a licensed structural engineer or civil engineer approved the modification to the
building and cable vault?
•
Will the cable vault extension enter into a roadway?
•
Will the building be extended over the top of the cable vault?
•
Will there be an exterior entrance to the cable vault?
•
Can the existing submersible pump, if applicable, support the extended area, or will an
additional pump be needed?
•
Will electricity be added for lighting or submersible pumps in the extended area?
•
Has long-term growth been considered in designing the cable vault?
•
Has the proper amount of labor for hand trenching been included?
•
Have the proper number of temporary forms been calculated to support the existing
conduits and cables during construction?
•
Will the cables be racked in the center of the cable vault, on the walls, or both?
•
Will additional core drills be required to route conduits or cables?
•
Are the appropriate pulling eyes in the proper locations for installing large balanced
twisted-pair cables?
•
Will there be adequate ventilation in the cable vault once it is extended?
•
Will downtime be required to reconfigure existing cables and equipment to facilitate this
overbuild?
•
Will the overbuild areas allow the proper cable bend radius and cable and splice support in
its final configuration?
OSP Design Reference Manual, 4th edition
13-24
© 2007 BICSI®
Chapter 13: Special Design Considerations
References
American National Standards Institute. ANSI J-STD-607-A. Commercial Building
Grounding (Earthing) and Bonding Requirements for Telecommunications. Arlington, VA:
Telecommunications Industry Association, 2002.
American National Standards Institute/Telecommunications Industry Association/Electronic
Industries Alliance. ANSI/TIA/EIA-568-B.1. Commercial Building Telecommunications
Cabling Standard, Part 1: General Requirements. Arlington, VA: Telecommunications
Industry Association, 2001.
———. ANSI/TIA/EIA-568-B.2. Commercial Building Telecommunications Cabling
Standard, Part 2: Balanced Twisted-Pair Cabling Components. Arlington, VA:
Telecommunications Industry Association, 2001.
———. ANSI/TIA/EIA-568-B.3. Optical Fiber Cabling Components Standard. Arlington,
VA: Telecommunications Industry Association, 2000.
———. ANSI/TIA/EIA-569-B. Commercial Building Standard for Telecommunications
Pathways and Spaces. Arlington, VA: Telecommunications Industry Association, 2004.
———. ANSI/TIA/EIA-570-B. Residential Telecommunications Infrastructure Standard.
Arlington, VA: Telecommunications Industry Association, 2004.
———. ANSI/TIA/EIA-606-A. Administration Standard for Commercial
Telecommunications Infrastructure. Arlington, VA: Telecommunications Industry
Association, 2002.
———. ANSI/TIA/EIA-758-A. Customer-Owned Outside Plant Telecommunications
Infrastructure Standard. Arlington, VA: Telecommunications Industry Association, 2004.
AT&T Network Systems. Customer Education and Training. Outside Plant Engineering
Handbook. Edminster, NJ: AT&T, 1994.
Bell Atlantic Network Services. Outside Plant Engineering Reference Manual. South
Plainfield, NJ: Bell, 1987.
BICSI®. OSP 100. Introduction to Outside Plant. Tampa, FL: BICSI, 2007.
———. OSP 110. Outside Plant Cable Design. Tampa, FL: BICSI, 2007
Common Ground Alliance. One-Call Systems International. Alexandria, VA: Common
Ground Alliance, 2003.
GTE. OSP Engineering. Volumes I and II. Dallas, TX: GTE Technical Documentation, 1991.
Institute of Electrical and Electronics Engineers, Inc.® National Electrical Safety Code®.
Piscataway, NJ: Institute of Electrical and Electronics Engineers, Inc., 2006.
Insulated Cable Engineers Association. ICEA S-83-596. Fiber Optic Premises Distribution
Cable. Carrollton, GA: Insulated Cable Engineers Association, 2001.
© 2007 BICSI®
13-25
OSP Design Reference Manual, 4th edition
Chapter 13: Special Design Considerations
References, continued
———. ANSI/ICEA S-84-608. Telecommunications Cable, Filled Polyolefin Insulated
Copper Conductor. Carrollton, GA: Insulated Cable Engineers Association, 2002.
———. ANSI/ICEA S-85-625. Aircore, Polyolefin Insulated, Copper Conductor
Telecommunications Cable. Carrollton, GA: Insulated Cable Engineers Association, 2002.
———. ANSI/ICEA S-90-661. Category 3, 5, & 5e Individually Unshielded Twisted-Pair
Indoor Cable for Use In General Purpose and LAN Communication Wiring Systems.
Carrollton, GA: Insulated Cable Engineers Association, 2000.
———. ANSI/ICEA S-98-688. Broadband Twisted-Pair Telecommunications Cable,
Aircore, Polyolefin Insulated Copper Conductors. Carrollton, GA: Insulated Cable
Engineers Association, 1997.
———. ANSI/ICEA S-99-689. Broadband Twisted-Pair Telecommunications Cable Filled
Polyolefin Insulated Copper Conductors. Carrollton, GA: Insulated Cable Engineers
Association, 1997.
———. ICEA S104-696. Standard for Indoor-Outdoor Optical Cable. Carrollton, GA:
Insulated Cable Engineers Association, 2003.
National Fire Protection Association, Inc. NFPA 70. National Electrical Code®, 2005 edition.
Quincy, MA: National Fire Protection Association, Inc., 2005.
———. NFPA 72®. National Fire Alarm Code®, 2007 edition. Quincy, MA: National Fire
Protection Association, Inc., 2007.
———. NFPA 75®. Standard for the Protection of Electronic Computer/Data Processing
Equipment. Quincy, MA: National Fire Protection Association, Inc., 2003.
———. NFPA 101®. Life Safety Code®. Quincy, MA: National Fire Protection Association,
Inc., 2006.
Underwriters Laboratories Inc.® UL 94. Test for Flammability of Plastic Materials for
Parts in Devices and Appliances. Northbrook, IL: Underwriters Laboratories, Inc., 2000.
———. UL 497. Standard for Protectors for Paired-Conductor Communications
Circuits. Northbrook, IL: Underwriters Laboratories, Inc., 2001.
———. UL 497A. Secondary Protectors for Communications Circuits. Northbrook, IL:
Underwriters Laborato