TR41.7-14-11-005-L (TIA-571-C-final draft).
Project Number
ANSI/TIA-PN-571-C
Document Title
Electrical, Thermal and Mechanical Environmental Performance Requirements
Source
TR41.7 (via the chairman Randy Ivans)
Name:
Contact
Distribution
Intended
Purpose of
Document
(Select one)
Complete
Address:
Randy Ivans
1285 Walt Whitman
Rd; Melville, NY
11747
Phone:
631-546-2269
Fax:
Email:
randy.ivans@ul.com
TR-41.7
X
For Incorporation Into TIA Publication
For Information
Other (describe) -
“The document to which this cover statement is attached is submitted to a TIA Engineering
Committee, Formulating Group, or sub-element thereof in accordance with the provisions of
TIA procedures including but not limited to Section 3.3.2 of the TIA Engineering Committee
Operating Procedures, all of which provisions are hereby incorporated by reference.”
Abstract
This document is the latest draft of the proposed TIA-571-C (revision to TIA-571-B). The base
document for this draft was TR41.7-14-02-005-MR3 (TIA-571-C-revision, TR41.7-May 2014 mtg).
TR41.7 discussed the contributions TR41.7-14-05-005-MR1 (TIA-571-C-revision-EMI-Ivans),
TR41.7-14-02-006-L (TIA-571-C-revision-RandomVib-Ivans) and TR41.7-14-08-005-TIA571-LBasicFunctionality at the May and August 2014 meetings. Some additional changes were agreed upon
at the August meeting (see TR41.7-14-11-003-R1-Arlington-MtgRpt-Ivans). This draft incorporates
all of the agreed upon revisions.
ANSI/TIA-PN-571-C
(To be published as ANSI/TIA-571-C)
Communications
User Premises Equipment
Electrical, Thermal and Mechanical Environmental
Performance Requirements
Formulated under the cognizance of TIA Subcommittee TR-41.7, Environmental and Safety
Considerations
With the approval of TIA Engineering Committee TR-41, Performance and Accessibility for
Communications Products
ANSI/TIA-PN-571-C
TABLE OF CONTENTS
FOREWORD______________________________________________________________6
1. SCOPE ______________________________________________________________7
2. REFERENCES ________________________________________________________8
3. ABBREVIATIONS, ACRONYMS, AND DEFINITIONS ____________________9
3.1.
Abbreviations and Acronyms ..................................................................................9
3.2.
Definitions................................................................................................................9
4. TECHNICAL REQUIREMENTS _______________________________________10
4.1.
General ...................................................................................................................10
Ambient Test Conditions.............................................................................10
Test Signals .................................................................................................10
Operating Temperature and Humidity Conditions ......................................10
4.2.
Physical Environment ............................................................................................11
Drop - Packaged ..........................................................................................11
Drop - Unpackaged .....................................................................................11
Vibration ......................................................................................................13
4.3.
Temperature and Humidity Environment ..............................................................14
Storage Thermal Soak (Long Term) ...........................................................14
Storage Thermal Shock ...............................................................................14
Storage Cycling ...........................................................................................15
Operating Conditions ..................................................................................15
4.4.
Electrical Environment ..........................................................................................16
Nominal Operating Voltage for EUT ..........................................................16
AC Voltage Sags and Transient Interruptions Requirements .....................16
Long Term AC Voltage Interruptions Requirements ..................................16
Lightning Surges .........................................................................................18
Electrostatic Discharge (ESD).....................................................................24
Annex A (Informative) – Power Line Faults__________________________________29
A.1.1 Overvoltage Conditions ...............................................................................29
A.1.2 Short Term Power Induction .......................................................................29
Annex B (Informative) – Bibliography ______________________________________30
Annex C (Informative) – Additional Considerations ___________________________31
C.1
Electromagnetic Interference .................................................................................31
C.1.1 Radio Frequency Immunity (RFI) ............... Error! Bookmark not defined.
C.1.2 Emissions.....................................................................................................31
C.2
Grounding Practices ...............................................................................................31
C.3
Telephone Line Voltages And Currents ................................................................31
C.4
Steady State Power Induction ................................................................................31
C.5
Short Term Power Induction ..................................................................................32
3
ANSI/TIA-PN-571-C
C.5.1
Method of Test ............................................................................................ 32
Annex D (Informative) Rationale for Telephone Line Overvoltage Tests _________ 33
D.1
Sources of Overvoltage ......................................................................................... 33
D.2
Analysis of Limiting Overvoltage Conditions ...................................................... 33
D.3
Performance of Telecommunications User Premises Equipment ......................... 34
D.4
2-Line and 4-Wire Circuits.................................................................................... 34
D.5
Multiple Sets.......................................................................................................... 34
D.6
Wiring Simulation ................................................................................................. 35
D.7
Primary Protector Coordination ............................................................................ 35
D.8
Test Points ............................................................................................................. 35
D.9
Test Conditions...................................................................................................... 35
D.10 Failure Conditions ................................................................................................. 36
Annex E (Informative) Rationale For Surges ________________________________ 37
E.1
Sources of Surges .................................................................................................. 37
E.2
Traditional Telecom Surge Specification .............................................................. 37
E.3
Surge Types ........................................................................................................... 38
E.3.1 L-type (Longitudinal) ................................................................................. 38
E.3.2 M-type (Metallic) ........................................................................................ 38
E.3.3 P-type (Power) ............................................................................................ 38
E.3.4 T-type (Transverse)..................................................................................... 38
E.3.5 I-type (Intra-building) ................................................................................. 38
E.4
Open Circuit Voltage and Voltage Waveshape ..................................................... 38
E.5
Short Circuit Current and Current Waveshape...................................................... 39
E.6
Surge Studies and Data.......................................................................................... 39
E.6.1 Telephone line monitoring .......................................................................... 39
E.6.2 Survey data ................................................................................................. 39
E.7
Standards on Surges .............................................................................................. 40
E.7.1 TIA-968-B .................................................................................................. 40
E.7.2 ANSI/IEEE C62.45 ..................................................................................... 40
E.7.3 IEC 61000-4-5 ............................................................................................ 40
E.8
Surge Likelihood ................................................................................................... 40
E.8.1 Level A and level B .................................................................................... 40
E.8.2 Level C ........................................................................................................ 40
E.9
Surges for Telecommunications Equipment ......................................................... 41
E.9.1 Metallic ....................................................................................................... 41
E.9.2 Longitudinal ................................................................................................ 41
E.9.3 Power .......................................................................................................... 41
E.9.4 Transverse ................................................................................................... 41
E.9.5 Ground ........................................................................................................ 41
4
ANSI/TIA-PN-571-C
Table of Figures
Figure 1 – Power Line and Telephone Line Surge Generators ............................................................22
Figure 2 – Application of Surge Generators...........................................................................................23
Table of Tables
Table 1 – Range of Temperature & Relative Humidity .........................................................................10
Table 2 – Temperature & Relative Humidity Test Points ......................................................................15
Table 3 – AC Voltage Sag and Short Duration Interruption Test Points ...............................................17
Table 4 – Long Term AC Voltage Interruptions Test Points .................................................................18
Table 5 – Lightning type abbreviations ..................................................................................................19
Table 6 – High Voltage Surges Parameters ............................................................................................21
Table 7 – ESD Response Mode Distribution..........................................................................................25
Table 8 – ESD Discharge voltages and methods....................................................................................25
Table 9 – Test Voltage vs. Altitude Multipliers .....................................................................................27
5
ANSI/TIA-PN-571-C
FOREWORD
(This foreword is not part of this Standard.)
This document is a TIA Telecommunications standard produced by Subcommittee TR-41.7 of
Committee TR-41. This standard was developed in accordance with TIA procedural guidelines, and
represents the consensus position of the Subcommittee, which served as the formulating group.
This standard describes environmental conditions that could be detrimental to such equipment. The
conditions are based on characteristics at the Customer Interface.
Some of the tests prescribed in this standard may involve the presence of hazardous voltages and
currents or other potential dangers to test personnel. Some of these hazards have been identified, and
appropriate warnings have been included in the text prescribing such tests. However, appropriate
safety precautions are always recommended when performing any laboratory test.
There are five annexes in this Standard, all of which are informative and are not considered part of this
Standard.
The leadership of the TR-41.7 Environmental and Safety Considerations Subcommittee (Chair: Randy
Ivans, UL LLC) acknowledges the written contributions provided by the following individuals in the
development of this standard.
Organization
Representative
UL LLC
Randy Ivans
AST Technology Labs Inc.
Don McKinnon
AST Technology Labs Inc.
James Bress
Embarq
Amar Ray

TE Connectivity
Al Martin
Chrysanthos
Chrysanthou

Thermo Keytek
Mike Hopkins

Thomson Inc.
Roger Hunt

Uniden
Al Baum

VTech
Steve Whitesell

Whitesell Consulting
Steve Whitesell
Telcordia Technologies
Previous Versions
TIA-571-C
Editor
Editor





Suggestions for improvement of this standard are welcome. They should be sent to:
Telecommunications Industry Association
Technology and Standards Department
1320 North Courthouse Rd.
Suite 200
Arlington, VA 22201
( http://www.tiaonline.org )
6
ANSI/TIA-PN-571-C
Communications - User Premises Equipment - Electrical, Thermal and Mechanical
Environmental Performance Requirements
1. SCOPE
This document establishes environmental performance criteria for communications equipment located
at the customer premises (on the subscriber’s side of the network interface or demarcation point) such
as telephones, modems, multi-line systems, wired and wireless routers, set top boxes, multi-media
equipment, alarm systems, etc. It defines the physical and electrical conditions that equipment may be
subjected to during its life-cycle and establishes test criteria that demonstrate the ability of the
equipment to operate as expected after being subjected to these conditions.
In some cases, environmental criteria and the related tests are categorized as either “normal” or
“severe”. Normal conditions are expected for all equipment while severe conditions may only apply to
certain types of equipment or equipment installed in more exposed environments.
This document may cover some topics addressed in regulatory or safety documents. Compliance to
this document is not intended to infer regulatory or safety compliance.
The scope of this document does not include network equipment such as central office switches,
digital subscriber line access multiplexers (DSLAMs), or similar equipment under the exclusive
control of a communications utility.
7
ANSI/TIA-PN-571-C
2. REFERENCES
The following standards contain provisions, which, through reference in this text, constitute provisions
of this Standard. At the time of publication, the editions indicated were valid. All standards are subject
to revision, and parties to agreements based on this Standard are encouraged to investigate the
possibility of applying the most recent editions of the standards indicated below. ANSI and TIA
maintain registers of currently valid national standards published by them.
1. ANSI/TIA-968-B, Telecommunications Telephone Terminal Equipment Technical Requirements
for Connection of Terminal Equipment to the Telephone Network
2. ANSI/TIA-1194-2011, Telecommunications - User Premises Equipment - Surge Resistibility of
Smart Grid Equipment Connected to either DC or 120/240 V Single Phase AC and Metallic
Communication Lines
3. ATIS-0600010-2.2012, Equipment Handling, Transportation Vibration, and Rail Car Shock
Requirements for Network Telecommunications Equipment.
4. International
Electrotechnical
Commission
(IEC)
Publication
61000-4-5-2005:
Electromagnetic Compatibility (EMC) - Part 4-5: Testing And Measurement Techniques - Surge
Immunity Test
5. International
Electrotechnical
Commission
(IEC)
Publication
61000-4-2-2008:
Electromagnetic Compatibility (EMC) - Part 4-2: Testing And Measurement Techniques Electrostatic Discharge Immunity Test
6. ITU-T Recommendation K.43 (07-2009): Immunity requirements for telecommunication
network equipment
7. UL 60950-1-2007, Information Technology Equipment - Safety - Part 1: General Requirements
8. UL 62368-1-2012, Audio/video, information and communication technology equipment – Part 1:
Safety requirements
8
ANSI/TIA-PN-571-C
3. ABBREVIATIONS, ACRONYMS, AND DEFINITIONS
3.1.
ABBREVIATIONS AND ACRONYMS
For the purposes of this Standard, the following abbreviations and acronyms apply.
1. DSLAM
Digital Subscriber Line Access Multiplexer
2. ESD
Electrostatic Discharge
3. EUT
Equipment Under Test
(Note: In other standards EUT is sometimes referred to as device under test (DUT))
4. FCC
Federal Communications Commission
5. Vnom
Nominal Voltage
3.2.
DEFINITIONS
For the purposes of this Standard, the following abbreviations and acronyms apply.
Basic Functionality
The EUT’s ability to perform its basic operational and interface
functions without loss of performance when the EUT is used as
intended.
If the performance criteria are not specified by the
manufacturer, these may be derived from the product description and
documentation and what the user may reasonably expect from the
apparatus if used as intended.
Earth (Ground)
A remote location considered to be at zero potential. Used
interchangeably with “ground.”
Grounding Conductor
The conductor connecting the equipment’s frame or grounding
terminal to a building’s ground system.
Network Interface or Demarcation Point
The point of interconnection between telephone company
communications facilities and terminal equipment, protective
apparatus or wiring at a subscriber's premises. The network interface
or demarcation point is located on the subscriber’s side of the
telephone company's protector, or the equivalent thereof in cases
where a protector is not employed, as provided under the local
telephone company’s reasonable and nondiscriminatory standard
operating practices.
Nominal Voltage
Commercial AC voltage of 120 Vrms.
Non-Condensing Rate
Temperature Stabilization
Rate of temperature change from a cold state to warm state that
avoids condensation on the EUT.
A steady state condition that is considered to exist if the temperature
change does not exceed 3°C (5.4°F) in 30 min.
9
ANSI/TIA-PN-571-C
4. TECHNICAL REQUIREMENTS
4.1.
GENERAL
Ambient Test Conditions
Unless otherwise stated, the Ambient conditions (room temperature and humidity) are defined as
+22°C ± 3°C (+68 to 77°F) and 40% ± 20% relative humidity. Ambient temperature is measured at a
distance of 15 inches (38 cm) in front of the equipment, at half the height of the equipment, after the
air temperature has stabilized.
Test Signals
All test signals shall be within ± 1% of the specified nominal value unless otherwise indicated.
Operating Temperature and Humidity Conditions
The applicable range of temperature and humidity that the EUT is expected to encounter is specified in
Table 1.
Table 1 – Range of Temperature & Relative Humidity
Temperature Limits
Humidity
Limits
Controlled Environment
Normal (continuous)
Exceptional (short-term)
5°C (41°F) to 40°C (104°F)
-5°C (23°F) to 49°C (120°F)
5% to 85%
5% to 90%
Partially Controlled Environment
-20°C (23°F) to 55°C (131°F)
5% to 95%
-40°C (-40°F) to 65°C (149°F)
(Includes the effects of solar loading)
5% to 95%
Condition
Uncontrolled Environment
Notes:
1.
2.
3.
4.
Examples of a controlled environment include the inside of most residential and business building locations.
Examples of a partially controlled environment include spaces inside of buildings such as attics, warehouses or
garages that are not environmentally controlled and where the thermal environment is more severe than a controlled
environment.
Examples of an uncontrolled environment include outside locations that are exposed to the elements such as
uncontrolled temperature and, humidity,
The full range of temperatures and humidity are not necessarily expected to occur concurrently, e.g. -20°C (23°F)
and 5% relative humidity.
Criteria for Basic Functionality
The criteria used for basic functionality for the EUT shall be included in the test report.
10
ANSI/TIA-PN-571-C
4.2.
PHYSICAL ENVIRONMENT
Drop - Packaged
4.2.1.1. Requirement
The EUT shall not exhibit the following failure conditions after packaged drop testing onto a concrete
surface:
1. Cabinet separation
2. Loose objects inside cabinet(s)
3. Loss of basic functionality
Separation of parts intended for removal such as battery door or memo covers shall not be considered a
failure if such parts can be re-installed as intended. If they cannot be installed as intended, then it shall
be considered a failure.
4.2.1.2. Method of Test
The referenced drop types are as follows:
A. Face Drop: The packaged EUT is dropped such that each face struck is approximately parallel
to the impact surface
B. Corner Drop: The packaged EUT is dropped such that, upon impact, a line from the struck
corner to the center of gravity of the packaged EUT is approximately perpendicular to the
impact surface.
4. The impact surface is to be perpendicular to the direction of motion of the EUT at the time of
impact
A. Packaged weight of 0-9 kg (0-20 lb.): One 76 cm (30-inch) Face drop on each face and one
76 cm (30-inch) Corner drop on each corner.
B. Packaged weight of 9-23 kg (20-50 lb.): One 61 cm (24-inch) Face drop on each face and
one 61 cm (24-inch) Corner drop on each corner.
C. Packaged weight of 23-45 kg (50-100 lb.): One 53 cm (21-inch) Face drop on each face and
one 53 cm (21-inch) Corner drop on each corner.
5. If after six or more successive drops a package has sustained visible damage, the EUT may be
repackaged before the packaged drop tests are resumed.
6. After all drops are performed, remove the EUT from the packaging and verify if the any of the
three conditions are exhibited.
Drop - Unpackaged
4.2.2.1. Requirement
The EUT shall not exhibit the following failure conditions after unpackaged impact testing onto
concrete covered with 3 mm (0.125-inch) asphalt tile or similar surface:
1. Cabinet separation
2. Loose objects inside cabinet(s)
3. Loss of basic functionality
Separation of parts intended for removal such as battery door or memo covers shall not be considered a
failure if such parts can be re-installed as intended. If they cannot be installed as intended, then it shall
be considered a failure.
4.2.2.2. Method of Test
The referenced drop types are as follows:
A. Random Drop: The EUT is positioned prior to release to ensure as nearly as possible that for
every six drops there is one impact on each of the six major surfaces and that the surface to be
struck is approximately parallel to the impact surface.
11
ANSI/TIA-PN-571-C
B. Face Drop: The unpackaged EUT is dropped such that each face struck is approximately
parallel to the impact surface
C. Corner Drop: The unpackaged EUT is dropped such that, upon impact, a line from the struck
corner to the center of gravity of the unpackaged EUT is approximately perpendicular to the
impact surface.
D. Edgewise Drop: The EUT is positioned on a flat surface. One edge of the rest face is
supported by a block so that the rest face makes an angle of 20° with the horizontal. The
opposite edge is lifted the designated height above the test surface and dropped.
E. Cornerwise Drop: The EUT is positioned on a flat test surface. One corner of the rest face is
supported by a block so that the rest face makes an angle of 20° with the horizontal. The
opposite corner is lifted the designated height above the test surface and dropped.
4. The impact surface is to be perpendicular to the direction of motion of the EUT at the time of
impact.
A. Hand-Held Equipment: Normally used at head height: Perform six Random drops of the
EUT from a height of 152 cm (60 inches)
B. Table (Desk) Top Equipment or Equipment capable of connecting to other Table Top
Equipment, 0-5 kilograms (0-11 lb.): Perform six Random drops of the EUT from a height of
76 cm (30-inch).
C. Other Equipment: The EUT is dropped as follows:
 EUT weight of 0-9 kg (0-20 lb.): Perform one 152 mm (6-inch) Face drop on each
designated rest face, one 76 mm (3-inch) face drop on all other faces and one 76 mm (3inch) Corner drop on each corner.
 EUT weight of 9-23 kg (20-50 lb.): Perform one 102 mm (4-inch) Face drop on each
designated rest face, one 51 mm (2-inch) face drop on all other faces and one 51 mm (2inch) Corner drop on each corner.
 EUT weight of 23-45 kg (50-100 lb.): Perform one 51 mm (2-inch) Face drop on each
designated rest face, one Edgewise drop and one Cornerwise drop from a height of 51 mm
(2-inch) on each edge and corner adjacent to the rest face.
5. After each individual drop, verify if the any of the three failure conditions in 4.2.2.1 are exhibited
12
ANSI/TIA-PN-571-C
Vibration
4.2.3.1. Requirement
The packaged EUT shall not exhibit the following failure conditions after the vibration tests described
in 4.2.3.2 or 4.2.3.3:
1. Cabinet separation
2. Loose objects inside cabinet(s)
3. Loss of basic functionality
Note: Conformance to this requirement is demonstrated by using method I or method II.
4.2.3.2. Test Method I (Sine Sweep)
The following sinusoidal simulation of transportation vibration is to be applied to the EUT once in
each of three orthogonal directions, X, Y and Z:
1. Place the EUT in the X orthogonal direction.
2. Apply a frequency sweep from 5 Hz to 100 Hz at an acceleration level of 5 m/s2 peak conducted at
a sweep rate of 0.1 octave per minute (approximately 45 minutes).
3. Apply frequency sweep from 100 Hz to 500 Hz at an acceleration level of 15 m/s2 peak conducted
at a rate of 0.25 octave per minute (approximately 10 minutes).
4. After both vibration test sweeps are performed, remove the EUT from the packaging and verify if
the any of the three failure conditions are exhibited.
5. Repeat for the Y orthogonal direction.
6. Repeat for the Z orthogonal direction.
4.2.3.3. Test Method II (Random)
Test the EUT in accordance with ATIS-0600010-2, section 6, Transportation Vibration Test Methods.
13
ANSI/TIA-PN-571-C
4.3.
TEMPERATURE AND HUMIDITY ENVIRONMENT
Environmental chambers shall be capable of controlling temperature within a tolerance of +/- 3oC, and
humidity within a tolerance of +/- 5% RH.
For temperature and humidity testing there are several factors to consider that may affect testing. This
document does not address the specifics related to these factors. These include but are not limited to:
1. Rate of change capability of the test chamber used.
2. Air flow rate of the test chamber.
3. Rate of change to prevent unintentional thermal shock to the EUT.
NOTE: To prevent unintentional thermal shock a rate of change <3°C per minute is
recommended.
4. Rate of change from a cold condition to warm condition to prevent condensation.
Storage Thermal Soak (Long Term)
4.3.1.1. Requirement
After being subjected to each of the following Thermal Soak conditions for at least 24 hours, the
unpackaged non-operational EUT shall provide basic functionality 2 hours after returning to ambient
conditions.
1. -40°C (-40°F) and any convenient humidity (the low temperature point).
2. +66°C (+150°F) at 15% RH (the high temperature point).
3. +32°C (+90°F) at 90% RH (the high relative humidity point).
4.3.1.2. Method of Test
1. Subject the unpackaged EUT in its non-operational state to the -40°C (-40°F) and any convenient
humidity storage condition for at least 24 hours.
2. Return the EUT to the ambient conditions (see clause 4.1.1) without causing condensation.
3. After 2 hours verify the basic functionality.
4. Repeat for the +66°C (+150°F) at 15% RH storage condition.
5. Repeat for the +32°C (+90°F) at 90% RH storage condition.
NOTE:
It is desirable to soak EUT at the high humidity point for 96 hours.
Storage Thermal Shock
4.3.2.1. Requirement
After being subjected to three of each the following thermal shocks (six total), the unpackaged nonoperational EUT shall provide basic functionality 2 hours after returning to ambient conditions.
1. +66°C (+150°F) and a relative humidity of 15% to ambient conditions (High Temperature to
Room Temperature)
2. -40°C (-40°F) and any convenient humidity to ambient conditions (Low Temperature to Room
Temperature)
4.3.2.2. Method of Test
1. Subject the unpackaged EUT in its non-operational state to the +66°C (+150°F) at 15% RH.
2. After the EUT reaches temperature stabilization, the EUT is then subjected to a sudden change to
ambient conditions (see clause 4.1.1).
3. After 2 hours verify the basic functionality.
4. Repeat the +66°C (+150°F) at 15% RH thermal shock condition two addition times.
5. Repeat for the -40°C (-40°F) and any convenient humidity thermal shock condition three times.
14
ANSI/TIA-PN-571-C
Storage Cycling
4.3.3.1. Requirement
After being subjected to the three temperature conditions in the test method for three cycles, the
packaged EUT shall provide basic functionality 2 hours after returning to ambient conditions.
4.3.3.2. Method of Test
1. Subject the packaged EUT in its non-operational state to each of the following three 30 minute
temperature conditions for three cycles:
A. 30 minutes at +66°C (+150°F) and 15 percent RH, followed by
B. 30 minutes at +32°C (+90°F) and 90 percent RH, followed by
C. 30 minutes at -40°C (-40°F) and any convenient humidity (Avoid condensing when changing
to higher temperatures).
2. After the three cycles are completed, the EUT is returned to the ambient conditions (see clause
4.1.1) at a non-condensing rate.
3. After 2 hours verify the basic functionality.
Operating Conditions
4.3.4.1. Requirement
1. The EUT shall be tested to the applicable intended use environmental conditions: Uncontrolled,
Partially Controlled, or Controlled.
2. For each of the applicable operating environmental condition, the EUT shall provide basic
functionality after being subjected to each environmental state test point for at least 6 hours.
4.3.4.2. Method of Test
The temperature and humidity test points that cover the environmental conditions identified in Table 2.
1. Subject the EUT in its operational state to the “Dry” environmental state for at least 6 hours then
verify the basic functionality.
2. Repeat for the “Hot” environmental state.
3. Repeat for the “Damp” environmental state.
4. Repeat for the “Cold” environmental state.
5. Returned the EUT to the ambient condition (see clause 4.1.1) without causing condensation.
NOTE:
Changes from one test condition to another should be done in a manner that avoids thermal shock to the
EUT.
Table 2 – Temperature & Relative Humidity Test Points
Environmental Condition
Uncontrolled
Environmental
State
(Includes the effects of solar
loading)
Partially Controlled
Controlled
Cold
–40°C (–40 °F) 50% RH
32°C (90°F) 90% RH
–20°C (–4°F) 50% RH
32°C (90°F) 90% RH
5°C (41°F) ~50% RH
27°C (81°F) 90% RH
60°C (140°F) 19% RH
65°C (149°F) 10% RH
46°C (115°F) 39% RH
46°C (115°F) 10% RH
40°C (104°F) 43% RH
40°C (104°F) 10% RH
Damp
Hot
Dry
15
ANSI/TIA-PN-571-C
4.4.
ELECTRICAL ENVIRONMENT
Commercial ac power may experience transient voltage interruptions lasting for up to one cycle and
short duration voltage sags lasting for up to several hundred cycles. Commercial ac power may also
experience longer duration interruptions and voltage sags. A system Nominal Voltage (Vnom) of 120
Vrms is assumed.
NOTE:
Nominal system voltage is defined in ANSI C84.1
Nominal Operating Voltage for EUT
4.4.1.1. Requirement
The EUT shall maintain basic functionality with utilization power line voltage range from 110 Vrms to
126 Vrms.
NOTE:
AC utilization voltage range is defined in ANSI C84.1, range A.
4.4.1.2. Method of Test
1. Subject the EUT with 110 Vrms power line voltage and verify the basic operation.
2. Repeat with 126 Vrms power line voltage
AC Voltage Sags and Transient Interruptions Requirements
4.4.2.1. Requirement
The EUT in any normal operating state shall not change state or lose any stored information for any
single voltage sag, dual voltage sag separated by an interval of 5 seconds, or transient voltage
interruptions.
NOTES:
1. Typical usage conditions, not worse case power consumption scenarios, should be used when testing for compliance
2. Two or possibly three voltage sags could occur in succession. Such sags would normally be separated by an interval of 2
to 5 seconds or longer.
4.4.2.2. Method of Test
1. Subject the EUT to the single transient interruptions and voltage sags in column 1 of Error!
Reference source not found. and verify the operation after each test condition.
2. Repeat the transient interruptions and voltage sags in column 1 of Error! Reference source not
found. twice with an interval of 5 seconds between the dual transient interruptions and voltage
sags.
3. Repeat steps 1 and 2 for columns 2 through 8.
4. Repeat steps 1 and 3 for the EUT in other applicable operating states.
Long Term AC Voltage Interruptions Requirements
4.4.3.1. Requirement
The EUT in any normal operating is permitted to change state (e.g. drop the call, reset, etc.) but shall
resume functionality, without user intervention, after any single voltage interruption or dual voltage
interruption separated by an interval of 5 seconds.
4.4.3.2. Method of Test
1. Subject the EUT to the single voltage interruption in column 1 of Table 4 and verify the operation
after each test condition.
2. Repeat the voltage interruptions in column 1 of Table 4 twice with an interval of 5 seconds
between the dual voltage interruptions.
3. Repeat steps 1 and 2 for columns 2 through 5.
16
ANSI/TIA-PN-571-C
4. Repeat step 1 for column 6.
5. Repeat steps 1 and 4 for the EUT in other applicable operating states.
Table 3 – AC Voltage Sag and Short Duration Interruption Test Points
Column 1
1 and
1.2
Cycles
16 to
20ms
Test
Points
(%V)
80%
(96V)
50%
(60V)
20%
(24V)
0%
(0V)
Column 2
Column 3
Column 4
Column 5
Column 6
Column 7
Column 8
>1.2 to
7.5 cycles
>20 to
125 ms
>7.5 to
30 cycles
>125 to
500 ms
>1.2 to
7.5 cycles
>20 to
125 ms
>7.5 to
60 cycles
>125 to
1000 ms
>30 to
120 cycles
>300 to
2000ms
>60 to
120 cycles
>1000 to
2000ms
>120 to
300 cycles
>2000 to
5000ms
At 40%
Vnom
At 50%
Vnom
At 60%
Vnom
At 70%
Vnom
At 80%
Vnom
At 90%
Vnom
At 90%
Vnom
Test
Points
Test
Points
Test
Points
Test
Points
Test
Points
Test
Points
Test
Points
Cycles ms Cycles
ms
Cycles
ms
Cycles
ms
Cycles
ms
Cycles
ms
Cycles
ms
1.5
25.0
8.0
133.3
1.5
25.0
8.0
133.3
32.0
533.3
64.0
1066.7 124.0 2066.7
3.0
50.0
13.5
225.0
3.0
50.0
13.5
225.0
39.0
650.0
78.0
1300.0 168.0 2800.0
4.5
75.0
19.0
316.7
4.5
75.0
19.0
316.7
46.0
766.7
92.0
1533.3 212.0 3533.3
6.0
100.0 24.5
408.3
6.0
100.0
24.5
408.3
53.0
883.3
106.0 1766.7 256.0 4266.7
7.5
125.0 30.0
500.0
7.5
125.0
30.0
32.0
39.0
46.0
500.0
533.3
650.0
766.7
60.0
64.0
1000.0 120.0 2000.0 300.0 5000.0
1066.7
53.0
60.0
17
78.0
92.0
883.3 106.0
1000.0 120.0
1300.0
1533.3
1766.7
2000.0
ANSI/TIA-PN-571-C
Table 4 – Long Term AC Voltage Interruptions Test Points
Column 1
Column 2
Column 3
Column 4
Column 5
Column 6
>1.2 to
7.5 cycles
>20-125 ms
>7.5 to
30 cycles
>125-500 ms
>30 to
60 cycles
>500-1000ms
>60 to
120 cycles
>1000-2000ms
>120 to
300 cycles
>2000-5000ms
> = 1 minute
At 0% Vnom
At 0% Vnom
At 0% Vnom
At 0% Vnom
At 0% Vnom
At 0% Vnom
Test Points
Test Points
Test Points
Test Points
Test Points
Test Points
Cycles
ms
Cycles
ms
Cycles
ms
Cycles
ms
Cycles
ms
Minutes
1.5
25.0
8.0
133.3
32.0
533.3
64.0
1066.7
124.0
2066.7
1
4.5
75.0
19.0
316.7
46.0
766.7
82.7
1377.8
168.0
2800.0
10
7.5
125.0
30.0
500.0
60.0
1000.0
101.3
1688.3
212
3533.3
60
-
-
-
-
120.0
2000.0
256
4266.7
-
-
-
-
-
-
300
5000.0
Lightning Surges
Lightning can cause high-voltage surges on communications leads connected to exposed outside plant
facilities (e.g. Tip and Ring, xDSL, etc.), on power conductors and on grounding conductors. The
surges can be a result of a direct strike to the conductors, induction due to a strike near the conductors,
or ground potential rise (GPR).
Typical connections for applying the surges are shown in Figure 2. The EUT shall be powered and the
normal operating interfaces shall be applied to the telephony leads, including the leads being surged,
unless stated otherwise.
NOTE:
Appropriate care should be taken to ensure that powering circuits and loop feed circuits used to power the EUT and
interfaces do not significantly affect the surge presented to the EUT.
The surges are applicable in all operating states of the EUT under test including connections to
EUT and grounding options. For the purposes of this Standard, two surge generators are used
tests, as shown in
18
ANSI/TIA-PN-571-C
Figure 1. One generator is used for telephone line surges and the other for the power line and ground
path surges. See Annex E for a general description of surge generators.
Premises equipment that is connected to one or more metallic conductive communication line(s) and
either a DC power source, or a 120/240 V single phase AC power service with the neutral grounded at
the service entrance shall comply with ANSI/TIA-1194, “Surge Resistibility of Smart Grid Equipment
Connected to either DC or 120/240 V Single Phase AC and Metallic Communication Lines.”
NOTE:
This standard specifies the test procedures and resistibility requirements under which the communications ports of
the equipment shall continue to demonstrate basic functionality when subjected to overvoltages and overcurrents on
either the power lines or the communications line(s). It covers the case where two or more services connected to the
equipment have ground connections that may be separated by significant impedance.
19
ANSI/TIA-PN-571-C
The types of surges to apply are defined as follows:
1. Type P surges are applied to branch circuit power connections of the EUT with the EUT powered.
Surges are applied between:
 the phase conductor and neutral conductor,
 the phase conductor and grounding conductor, and
 the phase/neutral conductors and grounding conductor (common mode).
2. Type M surges are applied to all outside plant tip-ring leads of the EUT. For each pair of tip-ring
connection points, surges are applied between Tip and Ring or, for EUT that has a grounding
conductor, surges are applied between Tip and Ring with Ring grounded, and then applied
between Tip and Ring with Tip grounded.
3. Type L surges are applied to all outside plant tip-ring leads of EUT that has a grounding
conductor. For each pair of tip-ring connection points, surges are applied between tip-ring
simultaneously and the grounding conductor.
4. Type T surges are applied to branch circuit power connections and all outside plant tip-ring leads
of the EUT with the EUT powered. Surges are applied between the phase/neutral conductors and
simplexed tip-ring leads. The grounding conductor (if one exists) is connected to simplexed tipring.
5. Type I surges are applied to all tip-ring leads of EUT that has a grounding conductor and is subject
only to intra-building surges. For each pair of tip-ring connection points, surges are applied
between tip-ring simultaneously and the grounding conductor.
Table 5 – Lightning type abbreviations
Conductor abbreviations
Surge type abbreviations
L = Line (“hot” or phase) conductor of power line
Type P = Power
N = Neutral conductor of power line
Type M = Metallic
G = Grounding conductor
Type L = Longitudinal
T = Tip
Type T = Transverse
R = Ring
Type I = Intrabuilding
solidus (/) means both conductors simultaneously
(longitudinal or common mode)
4.4.4.1. Requirement
1. After being subjected to surges in each operating state, the EUT shall have basic functionality after
all the following applicable surges per Table 6: P1, P3, L2, T2, I1.
NOTE:
Achieving operating states may require artificial conditions of the EUT not normally achievable. For example, a
battery may be used to close a switch hook relay for application of the surge stresses in the off-hook mode when it
is not practical for the equipment to be normally powered. This philosophy can be extended to the use of special
EUT software or other appropriate means.
When artificial means, or companion equipment, or both, are used to condition the EUT for testing the effect on the
test should be evaluated and care should be taken to ensure accurate test results. Document this in the test report.
20
ANSI/TIA-PN-571-C
2. After being subjected to surges in each operating state, the EUT shall have basic functionality after
application of each polarity in 100V increments from 100V up to the maximum voltage for the M2
and L2 surges in Table 6.
NOTE:
As the voltage is stepped up no components of the surge generator shall be changed.
3. After being subjected to surges in each operating state the EUT shall not be a fire or fragmentation
hazard after application of the following surges from Table 6: M3, L3.
4.4.4.2. Method of Test
1. The surges are applicable in all operating states of the EUT under test including connections to
other EUT and grounding options.
2. If the EUT uses a detachable line cord for its tip-ring connections, a test line cord having no more
than one-half ohm per conductor (approximately 3 meters of 26 gauge wire) is to be used to
connect the EUT to the surge generator.
3. All operating states of EUT that may affect compliance are to be tested using whatever means
necessary to obtain the various operating states.
NOTE: For example mechanically forcing a relay closed to obtain a different operating state.
4. For EUT that has voltage limiting circuitry a stepped increase of voltage up to the peak level
specified is to be used.
5. Sufficient time is to be allowed between surges to prevent cumulative heating of components.
6. All tests are to be conducted in accordance with the IEC 61000-4-5 and the specific requirements
of this standard.
7. The surge generator parameters, test set-up, and procedure for surging EUT given in IEC 61000-45 are to be used to the extent practicable.
21
ANSI/TIA-PN-571-C
Table 6 – High Voltage Surges Parameters
Type
P-1
Peak Voltage1
(volts)
Peak Current2
(amperes)
See TIA-968-B (Power line
surge)
P-2
6,000
3,000
P-3
6,000
3,000
M-2
M-3
L-2
L-3
See TIA-968-B (Telephone line
surge - Type A)
1,000
100
See TIA-968-B (Telephone line
surge - Type A)
1,000
100/lead
Application3
Error!
Reference
source not
found.2 a)
Error!
Reference
source not
found. 2b)
Error!
Reference
source not
found. 2a)
Error!
Reference
source not
found. 2d)
10x560 s
Error!
Reference
source not
found. 2d)
10x1000 s
Error!
Reference
source not
found. 2e)
10x560 s
Error!
Reference
source not
found. 2e)
10x1000 s
T-2
5,000
1,000
Error!
Reference
source not
found. 2c)
I-1
1,500
100
Error!
Reference
22
Between
Number of
Surges, each
polarity
L-to-N
8
L-to-G,
L/N-to-G
4
L-to-N
4
T-to-R
4
1
T/R-to-G
4
1
4
T/R-to-G
1
ANSI/TIA-PN-571-C
source not
found. 2e)
2x10 s
NOTES:
1. Peak voltage is measured at the output terminals of the surge generator with the output terminated in at least 10,000 ohms.
2. Peak current is measured at the output terminals of the surge generator with the output terminated in a short circuit.
3. The waveshape (where specified) applies to both open circuit voltage and short circuit current, and gives the maximum
rise time to peak and the minimum decay time to half-peak. The current waveshape decay to half peak should range between
the minimum requirement and two times the minimum requirement for all load values from 0 ohms to 10,000.
Figure 1 – Power Line Generator
23
ANSI/TIA-PN-571-C
1
Power
+/–
Line Surge
Generator
L
CPE
N
G
G
disconnect CPE
ground if present
1 +/–
Telephone
Line Surge
Generator
P-1 Testing (TIA-968-A)
a)a) P-1
Testing (TIA-968-B)
G
Power
Line Surge
Generator
G
1
+/–
L
N
T
CPE
R
G
d)d)
M-1M-2
& M-2
(TIA-968-A)
and
M-3Testing
Testing
(TIA
968-B) and
M-3
CPE
2*
+/–
ground
switch
G
* disconnect terminal 2
for L-to-G surge
1
Telephone +/–
Line Surge
Generator 2
+/–
P-2 Testing
c) P-2b)Testing
(CombinationWave
WaveGenerator)
Generator)
(Combination
T
CPE
R
G
G
1
+/–
Power
Line Surge
Generator 2
+/–
G
e)
& L-2
(TIA-968-A),
L-3,
and
Testing
e) L-1L-2
(TIA-968-B),
L-3
and
I-1I-1
Testing
(L-3
uses
10
x
1000
µs
generator)
(L-3 uses 10 X 1000s generator)
(I-1 uses 2 x 10 µs generator)
(I-1 uses 2 X 10 s generator))
3
L
T
CPE
N
G
3
R
*
* connect to EUT ground if present
T-1Testing
and T-2 Testing
b) c)T-2
(CombinationWave
Wave Generator)
Generator)
(Combination
Figure 2 – Application of Surge Generators
24
ANSI/TIA-PN-571-C
Electrostatic Discharge (ESD)
Electrostatic Discharge (ESD), either directly to EUT or indirectly to some nearby object, can be a
significant cause of EUT failure or malfunction. The adverse effects of ESD on one piece of EUT can
propagate to others connected to the network. EUT can be susceptible to ESD effects at all stages of
storage, installation, testing, operation, adjustment, maintenance, and repair.
An electrostatic charge may be developed on the human body, furnishings, and other objects as a result
of everyday actions and activities. The simple act of walking on a carpet or other insulating flooring
material can cause a charge to build up on an individual. The rolling or sliding of furnishings such as
carts and chairs across the floor, as well as contact with synthetic fabrics used in clothing and furniture
upholstery can generate large electrostatic potentials.
While it may not be possible or practical to protect equipment from the maximum ESD that may be
experienced, the intent of ESD testing is to stress the EUT with typical electrostatic discharges.
All tests are to be conducted in accordance with the IEC 61000-4-2 and the specific requirements of
this standard.
The user’s perception of performance for equipment after a discharge, other than no response at all,
falls into one of the following categories:
a) Non-recoverable: The user experiences a loss of expected service, such as equipment failure, and
loss or corruption of stored information. For example, the equipment may be damaged (typically a
semiconductor) or may experience a permanent processor lock-up.
b) Recoverable: The user perceives the equipment to have malfunctioned and must take some action
that involves ordinary use to recover, e.g., pressing a <DISPLAY> button to reset a display or
power cycling. Voice transmission drop-out that exceeds 1 second, or loss of a call in progress
may be also considered as recoverable.
c) Temporary: The user perceives a temporary loss of performance (for example, an audible click,
flicker on a video screen, data transmission errors that do not exceed one errored second or
transmission drop-out that does not exceed 1 second), but normal service is not disrupted.
Two types of ESD simulators are used:
1. Type 1 (IEC model): The test network consists of a 150-pF capacitor discharging through a 330ohm resistor1. This represents a human discharge through a small hand-held metallic object.
2. Type 2 (Human Body Model, or HBM): This represents a human discharge through a hand. The
test network consists of a 100-pF capacitor discharging through a 1500-ohm resistor2.
1
2
The waveshapes and calibration methods are given in IEC 61000-4-2.
A calibration method is given in MIL-STD-883C, Test Methods and Procedures for
Microelectronics.
25
ANSI/TIA-PN-571-C
4.4.5.1. Requirements
1. The response of EUT to a static discharge is of a statistical nature. The EUT shall not exceed the
Response Mode Distribution for each test point in Table 7 when using the voltage levels in Table
8.
Table 7 – ESD Response Mode Distribution
Non-Recoverable
0%
Recoverable
10%
Temporary
100%
2. The entries in Table 7 apply to each test point, for each operating state, not the aggregate
discharges applied to the entire EUT. For example, a 10% entry means that the indicated response
is acceptable if it occurs on no more than 2 of the 20 discharges applied to each test point.
3. It is desirable for EUT to comply with the performance criteria when direct discharges are applied
to internal areas that may be contacted during shipping, installation, maintenance, adjustment, or
repair.
4.4.5.2. Method of Test
4.4.5.2.1. Preparation
The test set-up for equipment is given in IEC 61000-4-2. Prior to the application of the test
discharges:
1. The EUT shall be configured with all necessary hardware and software and shall be operating in
accordance to its design specifications. Networked EUT shall be connected in a normal network
configuration.
2. EUT interface connection points, including power leads that provide a path for electrostatic
discharge currents during EUT operation shall be appropriately terminated3. For example, Tip and
Ring shall be connected to a telephone network or a network simulator that provides loop current,
ringing, and DTMF detection.
3. The EUT shall be stabilized at ambient test conditions immediately before testing.
4.4.5.2.2. Test Modes
1. ESD Simulator Application: Type 1 and Type 2 ESD simulators shall be applied to EUT in the
manner and at the voltage levels given in the following table. If the EUT is capable of having
different installation means, such as with and without a grounding conductor, each possible
installation means that can affect compliance shall be evaluated.
Table 8 – ESD Discharge voltages and methods
Simulator
Type 1 (IEC model)
Type 2 (HBM) (c)(d)
3
Discharge voltage and method
CONTACT (a)
AIR (b)
6 kV, direct and indirect
4 and 8 kV, direct
Not applicable
12 kV, direct
Besides ESD currents carried on intentional paths to ground, the free space capacitance of auxiliary
equipment may cause an interconnecting cable to carry significant ESD current even though the
auxiliary equipment has no path to ground.
26
ANSI/TIA-PN-571-C
Conditions applicable to Table 8:
a) Direct contact discharges are applied to conductive and static dissipative surfaces of the EUT
that have a discharge path to the grounding conductor. Ordinary paint is not considered to be
insulation and, therefore, painted metallic surfaces are subject to direct contact discharges.
b) Indirect contact discharges are applied to both the horizontal and vertical coupling planes.
c) Air discharges (sparking) are applied to insulating materials and to conductive and static
dissipative surfaces that are floating (ungrounded). Coatings, including paint, that are designed
to provide insulation are considered to render a metallic surface as insulated and, therefore,
coated metallic surfaces are subject to air discharges.
d) At the option of the manufacturer, a Type 1 (IEC model) simulator may be used.
2. Number of Discharges: At least 10 positive discharges and 10 negative discharges shall be applied
at each test point selected in accordance with 4.4.5.2.3. More than 10 discharges of each polarity
may be required to accommodate the various operating states of a sample (reference “test
Procedure section”)
3. Frequency of Discharges: Any charge remaining on the EUT shall be bled off after each discharge
via a high resistance to ground. Any effects on the EUT during the bleed-off are disregarded. The
time between successive discharges shall be at least 1 second.
4.4.5.2.3. Determination of Test Points
1. Areas on the EUT that are likely to be touched during normal operation shall be scanned to
determine their vulnerability to ESD. Examples of such areas include:
 EUT enclosures and their seams
 sockets designed for metallic plugs
such as telephone jacks
 exposed metallic shells of cable plugs and
connectors
 test plug receptacles
 exposed structural frame areas
 dials and keypads
 pushbuttons
 front panels
 circuit pack faceplates
 connecting cords
 light emitting diodes
 wrist strap jacks
 Switches
 Displays
 Lamps
 Consoles
 Handsets
 Headsets
 speakers
2. Points that are found to be vulnerable to ESD during scanning shall be used as the test points. At
least four test points shall be established for direct discharges, which are in addition to the indirect
discharges to the vertical and horizontal coupling planes. Additional test points may be chosen.
3. Circuit packs (as stand-alone assemblies), backplanes, and other intentionally exposed wiring shall
not be tested.
4. Scanning should be performed by setting the ESD simulator to continuous running (typically at 20
discharges per second) while discharging to possible test points. Scanning should be conducted
with an ESD simulator set at the specified test voltage. Multiple units may be scanned to
determine test points to prevent possible weakening of components or carbon tracking due to ESD
flashes during the scanning process. At the manufacturer’s option, when scanning insulated
surfaces for breakdown, the scan voltage may be reduced from the specified test voltage in
consideration of the altitude of the test facility4 by the multipliers in Table 9:
4
The correction is for the scanning voltage only, to determine if breakdown will occur at a given point
on the equipment. The compliance test voltage is not adjusted for altitude. The correction is from
IEC-950.
27
ANSI/TIA-PN-571-C
Table 9 – Test Voltage vs. Altitude Multipliers
Altitude Multiplier
500 m
1,000 m
0.94
0.89
Sea level
1
2,000 m
0.79
For other elevations use the following formula:
Vs  Vt e 0.000116h
where,
Vs
Vt
h
=
=
=
scan voltage
test voltage
altitude of test facility in meters relative to sea level
4.4.5.2.4. Test Procedure
1. In general, both direct and indirect discharges are applied for all operating states of the EUT. If
discharges to a EUT while in a primary operating state (e.g., off-hook) are sufficient to evaluate
the ESD vulnerability of the EUT while in a secondary operating state (e.g., hold), only the
primary state need be tested. However, if the sufficiency of such a procedure is not known, then all
operating states shall be tested.
2. A cordless telephone handset, while insulated from earth, is charged by applying direct contact
discharges to exposed metal such as the antenna or charging contacts. The handset is then
discharged to earth through the charging contacts by cradling the handset. This test method
(known as a charged body test) is applicable to similar hand-held battery powered EUT.
3. The bottom of EUT not normally carried during operation, and installed only by service personnel,
shall not be tested. If the EUT can be installed by users, the bottom shall be tested using the Type
1 simulator.
4. If a test point exhibits ESD sensitivity in more than one operating state, the ESD sensitivity for
each operating state is to be evaluated by distributing the discharges over each operating state to be
tested, e.g. 5 discharges on-hook and 5 discharges off-hook. However, no less than 3 discharges
(of each polarity) shall be applied per operating state so the total number of discharges can exceed
10 of each polarity. For example, a test point could receive 3 discharges each in an on-hook idle
state, on-hook ringing state, off-hook idle state, and an off-hook hold state, for a total of 12
discharges to the same test point.
5. Doors and panels are tested as follows:
If not required to be opened by the user, doors and panels shall remain closed during testing.
If required to be opened by the user for maintenance (e.g., to access batteries), parts behind the
door or panel are treated as if the door or panel wasn’t present, and shall only be subject to the
Type 1 simulator. However, only those operating states applicable to the maintenance operation
are to be considered. In addition, normal testing shall be conducted with the doors and panels
closed.
4.4.6
Electromagnetic Interference (EMI) – Immunity Requirements
4.4.6.1 EUT shall comply with the immunity requirements specified in ITU-T K.43, “Immunity
requirements for telecommunication network equipment”, clause 7.2.4 for radiated electromagnetic
fields and clause 7.2.5 for conducted signals. Radiated and conducted immunity tests shall be applied
to the relevant ports of the equipment according to Table 2 – Equipment for customer premises. Tests
shall only be carried out where the relevant port exists.
28
ANSI/TIA-PN-571-C
4.4.6.2 Two-wire Telephone Terminal Equipment (TTE) having an acoustic output and two-wire TTE
adjunct devices with a connection port for TTE having an acoustic output shall comply with the
requirements in ANSI/TIA-631, Telecommunications Telephone Terminal Equipment - Radio
Frequency Immunity Requirements.
29
ANSI/TIA-PN-571-C
ANNEX A (INFORMATIVE) – Power Line Faults
A.1.1 Overvoltage Conditions
During power line fault conditions (which may induce high voltages into telephone lines) or with a
power line cross (metallic contact between power conductors and telephone cables), protectors
normally limit potentials appearing between the tip and ring conductors (or between tip/ring and
ground) to less than 600 volts rms. In most cases, power-system fault detectors will limit the duration
of such voltages to 5 seconds. However, high resistance faults can last indefinitely. Such fault
conditions can cause a protector to permanently short either the tip or the ring terminal to ground, in
which case the fault voltage may appear as a metallic voltage. Requirements and test methods for
evaluating EUT during over-voltage conditions are given in UL-60950-1 or UL-62368-1 (equivalent
test methods). Rationale for the test methods is given in Annex D.
A.1.2 Short Term Power Induction
The EUT in the on-hook idle and off-hook operating states may experience short-term power induction
on the telephone line. See Annex C, section C.5 and ITU-T K.21 for additional information.
30
ANSI/TIA-PN-571-C
ANNEX B (Informative) – Bibliography
The following is a list of some generally applicable basic standards that are relevant to the
requirements of this Standard.
1. ATIS 0600401.2006(R2011), Network to Customer Installation Interfaces - Analog
Voicegrade Switched Access Lines Using Loop - Start and Ground-Start Signaling
2. ANSI C84.1-2011, Electrical Power Systems and Equipment - Voltage Rating (60Hz)
3. C62.45-2002, IEEE Recommended Practice on Surge Testing for Equipment Connected to LowVoltage (1000 V and Less) AC Power Circuits
4. 47 CFR Part 15 - Code of Federal Regulations (CFR), Title 47, FCC Part 15, Radio Frequency
Devices.
5. 47 CFR Part 68 - Code of Federal Regulations (CFR), Title 47, FCC Part 68, Connection of
Terminal Equipment to the Telephone Network.
6. ITU-T Recommendation K.21-2011, Protection Against Interference Resistibility Of
Telecommunication Equipment Installed In Customer Premises To Overvoltages And
Overcurrents
7. TIA-470.210-D-2010, Telecommunications Telephone Terminal Equipment Resistance and
Impedance requirements for Analog Telephones
8. TIA-631-B-2011, Telecommunications – Telephone Terminal Equipment – Radio Frequency
Immunity Requirements
9. TIA-968-B-2009, Telecommunications – Telephone Terminal Equipment – Technical
Requirements for Connection of Terminal Equipment to the Telephone Network
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ANSI/TIA-PN-571-C
ANNEX C (Informative) – Additional Considerations
C.1 ELECTROMAGNETIC INTERFERENCE
C.1.1 Emissions
Limits for radiated emissions, and conducted emissions on ac power leads, are specified in the FCC
requirements CFR Title 47 as applicable to the type of equipment under test.
Note: Unlicensed wireless devices are tested in accordance with the American National Standard for Testing
Unlicensed Wireless Devices, ANSI C63.10. Non-wireless devices are tested in accordance with the American
National Standard for Methods of Measurement of Radio-Noise Emissions from Low-Voltage Electrical and
Electronic Equipment in the Range of 9 kHz to 40 GHz, ANSI C63.4. Licensed devices are tested to the
appropriate methods as required and documented by the Federal Communications Commission.
C.2 GROUNDING PRACTICES
The following telecommunication equipment grounding practice is frequently used:
1. All circuit commons within the equipment enclosure are derived from a single ground
concentration point within the cabinet. Each cabinet's ground concentration point derives ground
from a single ground concentration point serving all system cabinets and peripherals collocated
with the system.
2. The system cabinets and all associated ducting hardware along with all collocated peripherals are
not connected to any ground source other than the system single-point ground, described in (1).
3. Service wires bringing commercial power to the cabinets do not share an enclosure or raceway
with any other system grounds, dc power distribution wires, or signaling wires. Commercial
power terminations not made by means of a connector are enclosed by race-ways and termination
boxes, whether these enclosures appear outside or within system cabinets. This is to ensure that ac
service wires cannot fault to circuitry within system cabinets or associated ducting hardware.
4. All system hardware are provided with an ac fault return path to the system single-point ground
which, in turn, is provided with a reliable path to the equipment’s grounding conductor. The path
from system equipment to single-point ground need not be a direct, dedicated path but can be any
reliable path to other system hardware which receives the above grounding path.
5. All sources of earthing (i.e., system signaling ground to the approved ground source etc.) connect
only to the system single-point ground. The intent of providing for a system single point ground is
to minimize ground loops and prevent lightning from finding a path through system components.
Other techniques that achieve equivalent results are also used.
C.3 TELEPHONE LINE VOLTAGES AND CURRENTS
EUT in the on-hook or the off-hook state can encounter voltages and currents at the network interface
as described in ATIS 0600401.
C.4 STEADY STATE POWER INDUCTION
Induction resulting from magnetic fields surrounding power distribution systems can result in
longitudinal voltages appearing on tip and ring conductors with respect to earth. Since the induced
voltage is in series with, and generally distributed along the loop or metallic facility involved, the
longitudinal mode voltage will be a function of the far-end termination of the loop, as well as the loop
characteristics. These voltages are usually low, although there is a small probability of being 50 volts
rms or greater when the terminal equipment has a high longitudinal impedance and the central office
end has a low longitudinal impedance.
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ANSI/TIA-PN-571-C
The induced current at a telephone interface connecting to terminal equipment possessing a low
longitudinal impedance usually does not exceed 100 mA rms (50 mA rms per conductor) when a low
longitudinal impedance is present at the central office end.
Longitudinal voltages may be converted to metallic voltages because of system impedance imbalances,
but the metallic voltages usually do not exceed 24.5 mV rms (60 dBrn with 3 kHz flat weighting).
Susceptibility of equipment to longitudinal voltage signals is addressed by the longitudinal balance
requirements in TIA-470.210-E.
C.5 SHORT TERM POWER INDUCTION
The following requirements and test methods and are being evaluated. The proposed requirement is
the EUT should provide basic functionality after being subjected to the test conditions specified below,
with the test signal of 600 Vrms, 60 Hz, limited to 1 A short circuit, for 200 ms.
The EUT would not be required to operate correctly during the test and is allowed to change states as a
result of the test.
C.5.1 Method of Test
1. Place the EUT in the On-hook state.
2. Apply the test signals:
A. Tip to Ground, Ring Grounded, then
B. Ring to Ground, Tip Grounded, then
C. Tip to Ground and Ring to Ground simultaneously
3. Repeat a total of five times.
4. Repeat steps 2 and 3 with the EUT in the Off-hook state.
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ANSI/TIA-PN-571-C
ANNEX D (Informative) Rationale for Telephone Line Overvoltage Tests
D.1 SOURCES OF OVERVOLTAGE
1. Contact with multi-grounded neutral primary power line, 4 kV to about 150 kV.
2. Induction from primary power line fault current.
3. Ground potential rise from primary power line fault current flowing to ground.
4. Contact with secondary power line, 120 V.
D.2 ANALYSIS OF LIMITING OVERVOLTAGE CONDITIONS
Longitudinal voltage (L-type) of up to 600 V rms can occur on inside wiring that is protected with 3mil carbon blocks. Asymmetrical operation of the carbon blocks can result in metallic voltages (Mtype) of 200 to 600 V rms (60 Hz).
Five conditions of overvoltage apply to terminal equipment:
1. An I2t of 2400 can result from power line contact to a telephone shielded cable. A test condition
of 40 amperes for 1.5 seconds was chosen to give this I2t. I2t is directly related to heating in
adiabatic processes.
2. Up to 7 amperes for 5 seconds can result from induction or from a ground potential rise after a
power line fault to a multi-grounded neutral conductor.
3. Induced currents of up to 2.2 amperes, steady state, can result from a power line fault to resistive
earth, wherein the fault current is not sufficient to cause the power line breakers to trip. Equipment
must be evaluated over the range of possible currents.
4. Induced voltages may be low enough not to activate voltage limiting devices. Equipment must be
evaluated over the range of possible voltages.
5. A 120 volt power line crossed with a telephone line can deliver up to 25 amperes to the telephone
wiring, limited by the wiring impedance.
Maximum induction voltages occur when a telephone cable is run in joint use with power lines.
Certain digital systems (such as an ISDN S/T interface) impose system limitations that limit the cable
length to 1000 meters or less. With such a short range, induced voltages are limited to less than 60
volts and conditions 3 and 4 above are not considered.
Contact conditions can occur on any telephone cable that is run with power cables, including short
lines within a campus environment. Therefore, contact conditions 1, 2, and 5 above apply for all exposed telephone cables.
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ANSI/TIA-PN-571-C
D.3 PERFORMANCE OF TELECOMMUNICATIONS USER PREMISES EQUIPMENT
Traditional telephone equipment, which has proven safe in years of use for millions of installations, is
not hazardous when subjected to the above overvoltage conditions because of the following equipment
parameters:
1. The traditional telephone is the 500-type made of flammability class HB material. An
electromechanical 500-type set as manufactured in the 1970’s is damaged by a 2.2-A current, but
the damage is confined to a protective metal can inside the set. The telephone's speech network
has an impedance of 50 ohms above 1 A, and fuses open at I2t =40, thereby protecting the
telephone line cord by limiting fault current. The tip and ring conductors are also isolated from
ground so that longitudinal voltages cause no damage. Some telephone systems with grounding
conductors have used heat coils (a type of fuse) on the telephone lines to protect the building
wiring.
2. The traditional telephone line cord was made of phosphor bronze tinsel conductor. Tinsel cord
softens at 2.2 A (long duration), at 7 A for 5 seconds, and at I2t =400 for short durations, but the
conductors do not melt through the jacket at these current levels.
3. Modular jacks can withstand 2.5 A (long duration) and I2t =400 (short durations) before the jack
material (early model jacks) begins to melt. Leaded jacks use 26 AWG stranded wire for the
leads.
4. Riser cable (26 AWG min., solid wire, the smallest gauge in use for premises wiring) can
withstand 5 A (long duration) and I2t =1200 (short durations). At I2t =2400 the conductors will
melt their insulation but will not fuse open. A 26 AWG cable longer than about 100 feet is self
protecting due to current limiting provided by its wire resistance.
Modems built to computer industry standards have traditionally used fire resistant enclosure materials
to provide safety.
D.4 2-LINE AND 4-WIRE CIRCUITS
The overvoltage tests are applied to a representative pair of tip-ring leads for equipment that has
multiple lines. If currents are induced into multiple lines going into a piece of equipment, the induced
current in one pair produces an EMF that induces a reversed current in the other pairs. Therefore, not
all pairs will have the maximum current, and worse case condition is likely to be testing one pair with
the maximum current.
Digital circuits often use a 4-wire (F-type) circuit, one pair for transmit and another pair for receive. A
4-wire circuit is not two 2-line circuits, e.g., the transmit and receive circuits are interconnected. To
test both circuits, a 4-wire test was designed to be used as a single test, instead of having several tests
on the various paths possible.
D.5 MULTIPLE SETS
The telephone line may be connected to several telephone stations (branches). Current in the main line
(unbranched) must be limited to I2t =400 to protect the line cord.
A common installation has a telephone set and an answering machine, each of which can terminate the
network in a low impedance after an overvoltage event. If each branch were fused for I2t =400, the
main line could see a much higher current. Assuming fault current is evenly distributed to the
branches, each branch (i.e., the telephone and answering machine) needs to limit short duration current to I2t =400/22= 100.
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ANSI/TIA-PN-571-C
D.6 WIRING SIMULATION
A composite model of a telephone line cord has a limiting l-t characteristic that is determined by the
following:
1. Long duration current limit is just over 2.2 A.
2. The current limit is just over 7 A at a 5-second duration.
3. Short duration (adiabatic) current-time characteristic is about I2t =100.
Characteristics (1) and (2) are within the test parameters. To provide an indication of whether
telephone wiring would be damaged during a short duration fault a fuse that opens at I2t =100 is
desirable to use for testing purposes. If such a fuse is blown open during testing, the telephone line
cord would be damaged. A fuse that meets these parameters is the Bussman MDL-2.
It is not necessary to use a fuse; the wiring model could be used to evaluate test results obtained with a
current probe. Also, 32 AWG copper wire has a suitable fusing characteristic to be used as an
indicator.
Not all telephone line cords use tinsel wire. When 26 AWG stranded wire (the same wire gauge as
riser cable) is used, equipment does not need to limit I2t to 100 because the line cord is considered
sufficiently robust.
D.7 PRIMARY PROTECTOR COORDINATION
If telecommunications user premises equipment provides a low impedance path to ground (including
operation of arrestors that provide a path to ground during surges), a fault current could by-pass the
primary protector and result in excessive current through the telephone building wire and the
equipment. The building wire can provide coordination if it has enough resistance, which is not
always the case. The equipment’s characteristics should coordinate with the protector operation,
which is achieved by having a fusing limit of I2t =100.
D.8 TEST POINTS
To minimize testing effort, only the worst case test conditions need be evaluated. These usually occur
at maximum voltage and current except when voltage or current limiting devices (usually MOVs and
fuses, PTCs or fusible resistors) are used. Then, conditions of maximum voltage and current that are
not interrupted by limiting devices need to be evaluated.
D.9 TEST CONDITIONS
1. Overvoltage conditions can be longitudinal or metallic. Both modes need to be evaluated
independently when equipment has a grounding conductor.
2. The test conditions apply to both series and terminal equipment. For series equipment testing,
terminal equipment is simulated as both a short circuit and an open circuit in separate tests.
3. No testing is necessary in the following situations:
a) Longitudinal tests are not necessary if a dielectric barrier exists between tip-ring and ground.
Instead, a simpler dielectric test can be conducted.
b) For metallic tests, series equipment (note that a line cord can be thought of as series
equipment) needs to be tested only to M-2 and M-3 when the terminal equipment is simulated
as a short circuit because the terminal equipment provides protection for the M-1 test.
c) When current (and possibly voltage) limiting is provided by a secondary protector suitable for
the purpose, either:
 The test conditions are adjusted so that they do not exceed the ratings of the protector, or
 The equipment is tested with the protector in place.
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ANSI/TIA-PN-571-C
D.10 FAILURE CONDITIONS
1. Fire hazards are evaluated using a cheesecloth indicator wrapped around the equipment under test.
2. Shock hazards are evaluated with a leakage current test applied after testing. A simpler dielectric
test may be used.
3. Telephone line cord hazards are evaluated against the wiring model (using an indicator fuse, 32
AWG wire or current probe).
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ANSI/TIA-PN-571-C
ANNEX E (Informative) Rationale For Surges
E.1 SOURCES OF SURGES
The most common source of surges on telephone tip-ring conductors results from a lightning strike to
an aerial or buried cable shield. The lightning current flowing on the shield to earth induces a voltage
into the cable pairs within the shield. If the ground path offers a high impedance to the lightning current, the voltage along the shield may build up enough to produce a side flash to the cable pairs within
the shield, especially at wire junctions where the only insulation is air spacing. A side flash can be
considered a direct lightning strike to tip-ring that is mitigated by a parallel ground path along the
shield.
Another source of surges to equipment is via the power service to the building. Lightning surges may
enter a building over the serving power service conductors. Such lightning activity can also result in a
local ground potential rise with respect to remote earth, which can cause telephone protectors to
operate.
E.2 TRADITIONAL TELECOM SURGE SPECIFICATION
When the 500-type set was being designed, a field study of induced lightning surges was conducted5 to
provide design information for the insulation. Direct lightning surges were not studied. Surge
voltages were measured behind a primary protector (using 3-mil carbon blocks) and found to have a
peak value of 600 volts. The voltage waveshape (needed to determine the energy of the surge) had an
envelope of a 10 us rise time to peak voltage, and a 1000 us fall time to half of peak voltage (referred
to as a 10x1000 us waveshape). The maximum induced voltage on the line side of the primary
protector was about 1000 volts. Therefore, a protector functions mainly to arrest voltages from direct
lightning hits and power crosses, which can be much higher than 1000 volts.
The peak induced current for cable runs is limited by cable impedance. The longer the cable run the
higher the induced voltage but the higher the wire resistance. This results in induction looking like a
constant current source of about 5 amperes but with a wide variation possible.
For metallic surges, current is limited by the impedance of the telephone terminating the line. The
traditional 500-type telephone has an impedance of 600 ohms at lightning frequencies, but surge currents saturate the hybrid voice transformer and cause its impedance to drop to the dc resistance of the
windings, about 40 ohms. If a 1000 volt surge with no cable impedance is applied to such a telephone,
the surge current would be 25 amperes.
For longitudinal surges applied to 500-type telephones, only insulation is stressed so that very little
current actually flows unless there is a breakdown. The voltage and current waveshapes are identical.
To test 500-type telephones, the current should be limited by the equipment under test, not the surge
generator impedance. Having a surge generator capable of delivering 100 amperes satisfies that aim
and was a design parameter for the Bell System surge simulator. It was not based on field studies.
5
D.W. Bodle, P.A. Gresh, “Lightning surges in paired telephone cable facilities,” BSTJ, March 1961.
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ANSI/TIA-PN-571-C
E.3 SURGE TYPES
E.3.1 L-type (Longitudinal)
Lightning surges induce voltages onto both tip and ring conductors. When a power line fault causes
arcing to cable pairs, the arcing usually occurs to both conductors. A ground potential rise has the
same effect as a line fault but in the reverse direction. All of these result in a longitudinal voltage,
which is a common mode voltage.
When several telephone line protectors are connected to the same protector ground, a discharge
through some protectors can cause a ground potential rise. For telephone lines whose protector is not
firing the ground potential rise adds to the voltage induced onto the telephone lines.
E.3.2 M-type (Metallic)
Metallic voltages (between tip and ring) are created when the primary protector grounds only one
conductor of the tip-ring pair. The longitudinal voltage on the other conductor then becomes a
metallic voltage, which is a differential mode voltage between tip and ring. A ground potential rise is
common to both tip and ring, so it does not affect the metallic voltage.
E.3.3 P-type (Power)
Power line surges commonly appear on a grounding conductor (causing a ground potential rise for the
telephone line as well as the power line) but the phase and neutral conductor can also be hit by
lightning between the power company transformer and the building being served. A high voltage on
the building’s grounding system can also arc over to phase and neutral, and the surge is then
transmitted through the power system as a common mode voltage.
E.3.4 T-type (Transverse)
Equipment with a 2-wire power cord usually has no ground reference but a P-type common mode
surge can appear on phase and neutral. The telephone line then becomes the ground reference for the
surge and arcing can occur between the power line and the telephone line. This is known as a
transverse surge. For equipment with a 3-wire power cord, transverse surges are still possible if the
insulation between phase/neutral and the grounding conductor is better than the insulation between
phase/neutral and the telephone line.
E.3.5 I-type (Intra-building)
An intra-building surge occurs when the steel structure of a building conducts a lightning discharge
which in turn induces a longitudinal voltage in telephone cables running parallel with the steel. This is
a source of longitudinal voltages for cables that do not connect to the outside plant.
E.4 OPEN CIRCUIT VOLTAGE AND VOLTAGE WAVESHAPE
Induction voltages are usually less than 1000 volts peak, but have elongated (10x1000 us) waveshapes. Direct voltages are often 4000 volts or more, with short (1.2x50 us) waveshapes.
Surges cause components to fail by different mechanisms, depending on the component’s weakness,
and one surge parameter cannot account for all failures. The voltage parameters are:
 Peak voltage: The peak voltage can cause carbon tracking in insulation and is a common source of
breakdown. A peak voltage of 1000 V covers nearly all induced surge voltages.
 Voltage heating: Leakage current through insulation can cause V2dt heating of the insulation. This
is not considered significant for insulators but played a role in deriving the FCC surges.
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ANSI/TIA-PN-571-C
E.5 SHORT CIRCUIT CURRENT AND CURRENT WAVESHAPE
Peak available current and current waveshape are very important for equipment that use voltage and
current limiting devices. In many older surge definitions the voltage waveshape and current
waveshape were considered the same since the surges were applied to insulation and only leakage
current resulted. In modern equipment, a surge protection element (like an MOV) becomes a low
impedance during a surge and significant surge current flows. The current waveshape under these
conditions is much shorter than the open circuit voltage waveshape, and 10x300 us is a typical current
waveshape.
The current parameters are:
 Peak current: The peak current can cause heating of diode junctions that have a constant voltage
drop. This is usually insignificant.
 Current heating: The V2dt heating of resistance elements can cause operation of fuses used to
provide power line fault protection. This is a service affecting fault that should be avoided.
E.6 SURGE STUDIES AND DATA
E.6.1 Telephone line monitoring
The Bell System6 collected detailed lightning surge data at several locations in the 1970’s. The data
did not distinguish between induced and direct lightning surges. The I2t plot followed a normal
distribution with a maximum value of 0.6 A2-s, except for one surge that had an I2t of 1.2 A2-s.
Simultaneous voltage-current waveforms were also recorded, which showed that the events with the
maximum voltage and current had a voltage and current decay time of less than 300 us, and tended to
be ringing waveforms (rather than simple exponential decays). While unipolar test waveshapes cannot
capture the variety of actual waveshapes, the energy content can be replicated.
E.6.2 Survey data
The Bell Labs studies were detailed records taken at a few sites. Other studies surveyed many sites but
with limited data. The two methods largely support each other. For example, in order to qualify solidstate protectors (SSP) for Central Offices, BellSouth Services conducted a surge survey 7 that showed a
maximum energy of 0.55 A2-s. Since the telecom installations around Central Offices is well
controlled, it is likely that only induction surges were observed. The SSPs withstood these induced
surges.
GTE Telephone Operations conducted a survey at the station end of the telecom loop 8, where the Bell
System studies were made. Much higher energies were observed. Damaged SSPs were sectioned and
the energy required to accomplish the observed damage was estimated. Also, damage from direct
lightning was distinguished from damage from power cross (which was more severe). The maximum
surge energy was equivalent to a 500 A, 10x1000 us waveform, which has an energy of 175 A 2-s.
This is 3 orders of magnitude greater than the energy from induced surges.
R. L. Carroll, “Loop transient measurements in Cleveland, South Carolina,” and other articles, BSTJ,
November 1980.
7 Mel Thrasher, “A solid-state solution,” Telephony, June 12, 1989.
8 C. A. Francis II, W. J. McCoy, “The analysis of solid-state overvoltage protection at customer
premises locations,” Compliance Engineering, May-June 1996.
6
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E.7 STANDARDS ON SURGES
E.7.1 TIA-968-B
(Industry replacement for FCC Rules, Part 68)
The 600 V, 10x1000 us waveshape used in the Bell System was not judged to be adequate when the
FCC instituted a registration program for telephones. Industry wide, protector let-through voltages
were more like 800 V peak, and that was the voltage selected for the FCC surge. However, the energy
of the 600 V, 10x1000 us surge as measured by V2dt (=360), was kept constant for the 800 V surge by
adjusting its waveshape to 10x560 us (V2dt =358).
For longitudinal voltages, a peak voltage of 1500 V was selected to represent a 1000 V surge and a
500 V ground potential rise. To maintain the same energy as used for metallic surges, the waveshape
was adjusted to 10x160 us which gives V2dt =360.
Like the Bell System surge, the surge generator was specified to provide 100 A to make sure the
generator did not limit the surge current, and no distinction was made between the open circuit voltage
and the short circuit current waveshapes.
E.7.2 ANSI/IEEE C62.45
IEEE 587 (adopted as ANSI C62.45 with some updates) established a surge for power lines that has an
open circuit voltage waveshape of 1.2x50 us, a short circuit current waveshape of 8x20 us, and an
output impedance of 2 ohms. This is typical of direct lightning surges. The peak voltage is specified
as 6 kV for location category B, limited by the arc over characteristic of power receptacles.
E.7.3 IEC 61000-4-5
This IEC surge standard has two circuits, the CCITT circuit for telephone line surges and the ANSI
waveshapes for power line surges (giving a schematic but without values). The CCITT circuit with the
25  resistor bypassed is also shown. Thus, the CCITT and ANSI circuits have become the
worldwide norms for surges. The standard gives severity levels for the power line surge of 1, 2, and 4
kV, de-pendent on the building installation category.
The open circuit voltage is specified at the output terminals of the surge circuit. Some standards
specify the voltage the capacitor is charged to. To achieve 5000 volts at the output terminals, the
capacitor must be charged to 6000 volts because of the voltage divider in the output.
E.8 SURGE LIKELIHOOD
E.8.1 Level A and level B
Induced surges are described as level A or level B. Level A does not mean average, but that level of
stress that equipment must withstand to have a reasonable life. Level B surges represent the envelope
of surge energies that equipment also needs to withstand. However, the equipment sees many more
level A surges than level B surges.
E.8.2 Level C
Terminal equipment is normally protected against direct lightning strikes by protectors, but occasional
poor grounding is unavoidable. Therefore, it is desirable for terminal equipment to withstand direct
strikes, and must at least be safe under such conditions. The level C lightning condition is taken from
the Bellcore generic requirement GR-1089.
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E.9 SURGES FOR TELECOMMUNICATIONS EQUIPMENT
E.9.1 Metallic
Surge M-1, level A, uses the CCITT generator. With the 25  resistor at 1000 volts, the I2t is 0.136.
Surge M-2, level B, uses the FCC 800 V, 10x560 µs generator which produces an I2t of 4.
Surge M-3, level C, uses the GR-1089 1000 V, 10x1000 µs generator which produces an I2t of 7.
E.9.2 Longitudinal
The level A longitudinal surge uses the CCITT generator at 1500 volts, with an I2t of 0.129 for each
leg.
The level B longitudinal surge actually represents a ground surge and has an I2t of 1.01 for each leg.
The level C surge has an I2t of 7 for each leg.
E.9.3 Power
The power line surges use the IEEE waveshape and an exposure likelihood based on IEC 61000-4-5.
That is, surges on phase and neutral rarely exceed 2500 volts, the value used for the FCC power line
surge. Ground surges are more likely to reach 5000 volts, the value used in TIA-571. The I2t at 2500
volts is 17.5, and at 5000 volts is 70.
E.9.4 Transverse
A transverse surge occurs between phase/neutral and tip/ring (acting as the ground path). Because the
telephone line has more resistance than the power line, an additional 3 ohms is added to each tip and
ring lead based on field experience. The I2t at 2500 volts is 2.8, and at 5000 volts is 11.2.
E.9.5 Ground
A ground surge is the same as a power line surge on the grounding conductor.
42