RECOMMENDED PRACTICE ANSI/ISA-RP12.06.01-2003 Formerly ANSI/ISA-RP12.06.01-1995 (R2002) Recommended Practice for Wiring Methods for Hazardous (Classified) Locations Instrumentation Part 1: Intrinsic Safety Approved 16 April 2003 TM ISA–The Instrumentation, Systems, and Automation Society This is a preview. Click here to purchase the full publication. Sure! Here are four ways in which a row of barriers can be connected to the I.S. (Intrinsic Safety) ground: Direct Connection to Ground Electrode: Each barrier can be directly connected to a separate grounding electrode. This ensures a high integrity, low-resistance return path for fault currents 1 2. Common Ground Bus: Barriers can be connected to a common ground bus, which is then connected to the grounding electrode. This method helps in maintaining a uniform ground potential 1. Shielded Cable: Using shielded cables to connect barriers to the ground can help in minimizing electromagnetic interference and ensuring a stable ground connection 2. Metal Enclosure Grounding: If the barriers are housed in a metal enclosure, the enclosure itself can be grounded. This provides an additional layer of protection and ensures that the entire system is at the same ground potential 3. Sure! Here are the definitions for the terms used in conjunction with zener safety barriers: End to End Resistance: This is the total resistance measured across the barrier from one end to the other. It includes the resistance of all components within the barrier, such as the zener diodes and series resistors 1. Fuse Rating: The fuse rating indicates the maximum current the fuse can handle before it blows. In zener barriers, the fuse protects the zener diodes from excessive current, ensuring the circuit remains safe 2. Maximum Voltage in the I.S. Circuit: This is the highest voltage that can appear across the intrinsically safe connections of the associated apparatus under fault conditions. It is crucial for ensuring that the voltage does not exceed safe limits 3. Maximum Current in the I.S. Circuit: This refers to the maximum current that can be drawn from the intrinsically safe connections of the associated apparatus under fault conditions. It ensures that the current remains within safe limits to prevent ignition in hazardous areas 4. ANSI/ISA-RP12.06.01-2003 Recommended Practice for Wiring Methods for Hazardous (Classified) Locations Instrumentation Part 1: Intrinsic Safety ISBN: 1-55617-865-4 Copyright © 2003 by ISA —The Instrumentation, Systems, and Automation Society. All rights reserved. Not for resale. Printed in the United States of America. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means (electronic mechanical, photocopying, recording, or otherwise), without the prior written permission of the Publisher. ISA 67 Alexander Drive P.O. Box 12277 Research Triangle Park, North Carolina 27709 This is a preview. Click here to purchase the full publication. —3— ANSI/ISA-RP12.06.01-2003 Preface This preface, as well as all footnotes and annexes, is included for information purposes and is not part of ANSI/ISA-RP12.06.01-2003. This document has been prepared as part of the service of ISAthe Instrumentation, Systems, and Automation Societytoward a goal of uniformity in the field of instrumentation. To be of real value, this document should not be static but should be subject to periodic review. Toward this end, the Society welcomes all comments and criticisms and asks that they be addressed to the Secretary, Standards and Practices Board; ISA; 67 Alexander Drive; P. O. Box 12277; Research Triangle Park, NC 27709; Telephone (919) 549-8411; Fax (919) 549-8288; E-mail: standards@isa.org. The ISA Standards and Practices Department is aware of the growing need for attention to the metric system of units in general, and the International System of Units (SI) in particular, in the preparation of instrumentation standards. The Department is further aware of the benefits to USA users of ISA standards of incorporating suitable references to the SI (and the metric system) in their business and professional dealings with other countries. Toward this end, this Department will endeavor to introduce SI-acceptable metric units in all new and revised standards, recommended practices, and technical reports to the greatest extent possible. Standard for Use of the International System of Units (SI): The Modern Metric System, published by the American Society for Testing & Materials as IEEE/ASTM SI 1097, and future revisions, will be the reference guide for definitions, symbols, abbreviations, and conversion factors. It is the policy of ISA to encourage and welcome the participation of all concerned individuals and interests in the development of ISA standards, recommended practices, and technical reports. Participation in the ISA standards-making process by an individual in no way constitutes endorsement by the employer of that individual, of ISA, or of any of the standards, recommended practices, and technical reports that ISA develops. CAUTION — ISA ADHERES TO THE POLICY OF THE AMERICAN NATIONAL STANDARDS INSTITUTE WITH REGARD TO PATENTS. IF ISA IS INFORMED OF AN EXISTING PATENT THAT IS REQUIRED FOR USE OF THE DOCUMENT, IT WILL REQUIRE THE OWNER OF THE PATENT TO EITHER GRANT A ROYALTY-FREE LICENSE FOR USE OF THE PATENT BY USERS COMPLYING WITH THE DOCUMENT OR A LICENSE ON REASONABLE TERMS AND CONDITIONS THAT ARE FREE FROM UNFAIR DISCRIMINATION. EVEN IF ISA IS UNAWARE OF ANY PATENT COVERING THIS DOCUMENT, THE USER IS CAUTIONED THAT IMPLEMENTATION OF THE DOCUMENT MAY REQUIRE USE OF TECHNIQUES, PROCESSES, OR MATERIALS COVERED BY PATENT RIGHTS. ISA TAKES NO POSITION ON THE EXISTENCE OR VALIDITY OF ANY PATENT RIGHTS THAT MAY BE INVOLVED IN IMPLEMENTING THE DOCUMENT. ISA IS NOT RESPONSIBLE FOR IDENTIFYING ALL PATENTS THAT MAY REQUIRE A LICENSE BEFORE IMPLEMENTATION OF THE DOCUMENT OR FOR INVESTIGATING THE VALIDITY OR SCOPE OF ANY PATENTS BROUGHT TO ITS ATTENTION. THE USER SHOULD CAREFULLY INVESTIGATE RELEVANT PATENTS BEFORE USING THE DOCUMENT FOR THE USER’S INTENDED APPLICATION. HOWEVER, ISA ASKS THAT ANYONE REVIEWING THIS DOCUMENT WHO IS AWARE OF ANY PATENTS THAT MAY IMPACT IMPLEMENTATION OF THE DOCUMENT NOTIFY THE ISA STANDARDS AND PRACTICES DEPARTMENT OF THE PATENT AND ITS OWNER. ADDITIONALLY, THE USE OF THIS DOCUMENT MAY INVOLVE HAZARDOUS MATERIALS, OPERATIONS OR EQUIPMENT. THE DOCUMENT CANNOT ANTICIPATE ALL POSSIBLE APPLICATIONS OR ADDRESS ALL POSSIBLE SAFETY ISSUES ASSOCIATED WITH USE IN HAZARDOUS CONDITIONS. THE USER OF THIS DOCUMENT MUST EXERCISE SOUND PROFESSIONAL JUDGMENT CONCERNING ITS USE AND APPLICABILITY UNDER THE USER’S Copyright 2003 ISA. All rights reserved. This is a preview. Click here to purchase the full publication. ANSI/ISA-RP12.06.01-2003 —4— PARTICULAR CIRCUMSTANCES. THE USER MUST ALSO CONSIDER THE APPLICABILITY OF ANY GOVERNMENTAL REGULATORY LIMITATIONS AND ESTABLISHED SAFETY AND HEALTH PRACTICES BEFORE IMPLEMENTING THIS DOCUMENT. THE USER OF THIS DOCUMENT SHOULD BE AWARE THAT THIS DOCUMENT MAY BE IMPACTED BY ELECTRONIC SECURITY ISSUES. THE COMMITTEE HAS NOT YET ADDRESSED THE POTENTIAL ISSUES IN THIS VERSION. The following people served as voting members of ISA Subcommittee SP12.6: NAME COMPANY D. Bishop, Managing Director R. Masek, Chair N. Abbatiello R. Allen W. Bennett K. Boegli C. Bombria J. Bossert R. Cardinal A. Engler T. Feindel W. Fiske L Goettsche B. Larson J. Miller A. Mobley O. Murphy E. Olson J. Oudar A. Page B. Schaefer P. Schimmoeller T. Schnaare D. Wechsler C. Wellman Consultant CSA International Eastman Kodak Co. Honeywell Inc. Pepperl + Fuchs Inc. Phoenix Contact Inc. Consultant Hazloc Inc. Bently Nevada LLC EGS Electrical Group R. Stahl Inc. Intertek Testing Services Consultant Turck Inc. Detector Electronics Corp. 3M Co. Brooks Instruments Ellis Engineering Co. ExLoc Corp. MSHA Approval & Certification Center Underwriters Laboratories Inc. CSA International Rosemount Inc. Dow Chemical Co. DuPont Engineering The following people served as voting members of ISA Committee SP12: NAME COMPANY T. Schnaare, Chair W. Lawrence, Vice Chair D. Bishop, Managing Director N. Abbatiello D. Ankele B. Apel A. Ballard W. Bennett K. Boegli R. Brodin R. Buschart R. Cardinal C. Casso M. Coppler J. Cospolich Rosemount Inc. FM Approvals Consultant Eastman Kodak Company Underwriters Laboratories Inc. MSA Instrument Crouse Hinds Division of Cooper Industries Pepperl + Fuchs Inc. Phoenix Contact Inc. Fisher Controls Intl. Inc. PC & E Inc. Bently Nevada Corp. Schlumberger Oilfield Services Ametek Inc. Waldemar S. Nelson & Company Inc. Copyright 2003 ISA. All rights reserved. This is a preview. Click here to purchase the full publication. —5— J. Costello S. Czaniecki T. Dubaniewicz U. Dugar A Engler T. Feindel W. Fiske G. Garcha D. Jagger F. Kent J. Kuczka B. Larson E. Magison R. Masek A. Mobley A. Page J. Propst P. Schimmoeller D. Wechsler C. Wellman ANSI/ISA-RP12.06.01-2003 Henkel Corporation Intrinsic Safety Concepts Inc. NIOSH Mobil Chemical Company EGS Electrical Group R. Stahl Inc. Intertek Testing Services GE Power Systems 9 Darnton Gardens Honeywell Inc. Killark Turck Inc. Consultant CSA International 3M Company MSHA Approval & Certification Center Equilon Enterprises CSA International Dow Chemical Company DuPont Engineering This document was approved for publication by the ISA Standards and Practices Board on 22 October 2002. NAME COMPANY M. Zielinski, Chair D. Bishop D. Bouchard M. Cohen M. Coppler B. Dumortier W. Holland E. Icayan A. Iverson R. Jones V. Maggioli T. McAvinew A. McCauley, Jr. G. McFarland R. Reimer J. Rennie H. Sasajima I. Verhappen R. Webb W. Weidman J. Weiss M. Widmeyer C. Williams G. Wood Emerson Process Management David N Bishop, Consultant Paprican Consultant Ametek, Inc. Schneider Electric Southern Company ACES Inc Ivy Optiks Dow Chemical Company Feltronics Corporation ForeRunner Corporation Chagrin Valley Controls, Inc. Westinghouse Process Control Inc. Rockwell Automation Factory Mutual Research Corporation Yamatake Corporation Syncrude Canada Ltd. POWER Engineers Parsons Energy & Chemicals Group KEMA Consulting Stanford Linear Accelerator Center Eastman Kodak Company Graeme Wood Consulting Copyright 2003 ISA. All rights reserved. This is a preview. Click here to purchase the full publication. This page intentionally left blank. This is a preview. Click here to purchase the full publication. —7— ANSI/ISA-RP12.06.01-2003 Table of Contents Preface .......................................................................................................................................................... 3 1 Purpose ................................................................................................................................................ 9 2 Scope ................................................................................................................................................... 9 3 Definitions ............................................................................................................................................. 9 4 Article 504 and 505 of the NEC (ANSI/NFPA 70-2002) with explanation .......................................... 14 5 Guidelines for combinations of apparatus under the entity concept .................................................. 44 6 Maintenance and inspection............................................................................................................... 46 Annex A — Explanatory notes .................................................................................................................... 49 Annex B — Wiring in hazardous (classified) locations ............................................................................... 53 Annex C — Marking for the zone classification system .............................................................................. 55 Annex D — References .............................................................................................................................. 57 Copyright 2003 ISA. 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