IEC 61156-12:2025

Multicore and symmetrical pair/quad cables for digital communications - Part 12: Symmetrical single pair cables with transmission characteristics up to 1,25 GHz - Work area wiring - Sectional specification

IEC 61156-12:2025 specifies cables intended to be used for single balanced pair cabling for office, home and industrial application described in ISO/IEC 11801-1:2017 and ISO/IEC 11801:2017/AMD1 . An example of existing application is 1000BASE-T1, see ISO/IEC TR 11801 9906. The transmission characteristics of these cables are specified up to a frequency of 1,25 GHz and at a temperature of 20 °C. The T1-B type cable is specified from 0,1 MHz to 600 MHz, the T1 C type cable from 0,1 MHz to 1,25 GHz. Depending on the MICE environment and the installation conditions, either unscreened or screened cables can be used. A blank detail specification can be found in Annex A. This second edition cancels and replaces the first edition published in 2021. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) additional cable type in support of T1-C generic single pair cabling up to 1,25 GHz;
b) introduction of low frequency coupling attenuation as an integral parameter describing screening efficiency at frequencies below 30 MHz.

General Information

• Status: Published
• Publication Date: 29-Apr-2025
• ICS: 33.120.20 - Wires and symmetrical cables
• Technical Committee: SC 46C - Wires and symmetric cables
• Drafting Committee: WG 7 - TC 46/SC 46C/WG 7
• Current Stage: PPUB - Publication issued
• Start Date: 30-Apr-2025
• Completion Date: 23-May-2025

Relations

• Revises: IEC 61156-12:2021 - Multicore and symmetrical pair/quad cables for digital communications - Part 12: Symmetrical single pair cables with transmission characteristics up to 600 MHz - Work area wiring - Sectional specification
• Effective Date: 05-Sep-2023

Overview

IEC 61156-12:2025 is the IEC sectional specification for symmetrical single pair cables used in work area wiring for digital communications. It defines transmission characteristics up to 1.25 GHz (measured at 20 °C) and covers both unscreened and screened single balanced pair cabling intended for office, home and industrial applications referenced in ISO/IEC 11801-1:2017 and its amendment. This second edition (2025) updates the 2021 edition by adding a higher-performance cable type (T1‑C) and introducing low frequency coupling attenuation as a screening-efficiency parameter.

Key topics and technical requirements

IEC 61156-12:2025 specifies electrical, mechanical and environmental requirements, including:

• Cable types and frequency ranges
  • T1‑B: 0.1 MHz – 600 MHz
  • T1‑C: 0.1 MHz – 1.25 GHz (new in 2025 edition)
• Transmission characteristics
  • Attenuation, phase/delay and velocity of propagation, impedance and return loss
  • Unbalance parameters (TCL, EL TCTL) and pair-to-pair crosstalk
  • Alien (exogenous) near‑end and far‑end crosstalk (PS ANEXT, PS AACR‑F)
• Screening performance
  • Transfer impedance and coupling attenuation
  • Low frequency coupling attenuation (new integral screening parameter below 30 MHz)
• Electrical tests
  • Conductor resistance, resistance unbalance, mutual capacitance, dielectric strength, insulation resistance
• Mechanical and environmental tests
  • Bending radius, tensile and elongation tests, crush/impact, temperature ageing, damp heat, UV, wicking, flame and smoke characteristics
• Bundled cable requirements
  • NEXT, ACR‑F and bundled behaviour for multiple pairs in one sheath
• Informative annex
  • Blank detail specification (Annex A) and background (Annex B)

Applications and intended users

IEC 61156-12:2025 is intended for:

• Cable manufacturers designing and qualifying symmetrical single pair products (T1‑B, T1‑C)
• Network designers and system integrators specifying work area cabling for high-speed single-pair Ethernet or similar digital services (e.g., 1000BASE‑T1 referenced)
• Test laboratories and certification bodies performing verification and compliance testing
• Procurement and specification writers in office, home and industrial environments

The standard helps ensure predictable electrical performance, screening effectiveness, mechanical durability and environmental robustness for modern single-pair digital applications.

Related standards

• ISO/IEC 11801-1:2017 (generic cabling for work area wiring)
• ISO/IEC TR 11801 9906 (example application: 1000BASE‑T1)
• Other parts of IEC 61156 series covering multicore and pair/quad cables

Keywords: IEC 61156-12:2025, single pair cables, 1.25 GHz, T1-C, work area wiring, coupling attenuation, transfer impedance, ISO/IEC 11801.

Standards Content (Sample)

IEC 61156-12 ®
Edition 2.0 2025-04
REDLINE VERSION
INTERNATIONAL
STANDARD
Multicore and symmetrical pair/quad cables for digital communications –
Part 12: Symmetrical single pair cables with transmission characteristics up to
600 MHz 1,25 GHz – Work area wiring – Sectional specification

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IEC 61156-12 ®
Edition 2.0 2025-04
REDLINE VERSION
INTERNATIONAL
STANDARD
Multicore and symmetrical pair/quad cables for digital communications –
Part 12: Symmetrical single pair cables with transmission characteristics up to
600 MHz 1,25 GHz – Work area wiring – Sectional specification
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 33.120.20 ISBN 978-2-8327-0407-3
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Installation considerations . 7
4.1 General remarks . 7
4.2 Bending radius of installed cable . 7
4.3 Climatic conditions . 7
5 Materials and cable construction . 7
5.1 General remarks . 7
5.2 Cable construction . 8
5.3 Conductor . 8
5.4 Insulation . 8
5.5 Cable element. 8
5.6 Screening of the cable element . 8
5.7 Cable make-up . 8
5.8 Screening of the cable core . 8
5.9 Sheath . 9
5.10 Identification . 9
5.11 Finished cable . 9
6 Characteristics and requirements . 9
6.1 General remarks . 9
6.2 Electrical characteristics and tests . 10
6.2.1 Conductor resistance . 10
6.2.2 Resistance unbalance . 10
6.2.3 Dielectric strength. 10
6.2.4 Insulation resistance . 10
6.2.5 Mutual capacitance . 10
6.2.6 Capacitance unbalance . 10
6.2.7 Transfer impedance . 10
6.2.8 Coupling attenuation and low frequency coupling attenuation . 11
6.2.9 Current-carrying capacity . 12
6.3 Transmission characteristics . 12
6.3.1 Velocity of propagation (phase velocity). 12
6.3.2 Phase delay and differential delay (delay skew) . 12
6.3.3 Attenuation (α) . 13
6.3.4 Unbalance attenuation (TCL and EL TCTL) . 13
6.3.5 Alien (exogenous) near-end crosstalk (PS ANEXT) . 15
6.3.6 Alien (exogenous) far-end crosstalk (PS AACR-F) . 15
6.3.7 Alien (exogenous) crosstalk of bundled cables . 16
6.3.8 Impedance . 16
6.3.9 Return loss (RL) . 16
6.4 Mechanical and dimensional characteristics and requirements . 17
6.4.1 Dimensional requirements . 17
6.4.2 Elongation at break of the conductor . 17
6.4.3 Tensile strength of the insulation . 17
6.4.4 Elongation at break of the insulation . 17
6.4.5 Adhesion of the insulation to the conductor. 17
6.4.6 Elongation at break of the sheath . 18
6.4.7 Tensile strength of the sheath. 18
6.4.8 Crush test of the cable . 18
6.4.9 Impact test of the cable . 18
6.4.10 Bending under tension . 18
6.4.11 Repeated bending of the cable . 18
6.4.12 Tensile performance of the cable . 18
6.4.13 Shock-test requirements of the cable . 18
6.4.14 Bump-test requirements of the cable . 18
6.4.15 Vibration-test requirements of a cable . 18
6.5 Environmental characteristics . 18
6.5.1 Shrinkage of the insulation . 18
6.5.2 Wrapping test of the insulation after thermal ageing . 18
6.5.3 Bending test of insulation at low temperature . 19
6.5.4 Elongation at break of the sheath after ageing . 19
6.5.5 Tensile strength of the sheath after ageing . 19
6.5.6 Sheath pressure test at high temperature . 19
6.5.7 Cold bend test of the cable . 19
6.5.8 Heat shock test . 19
6.5.9 Damp heat steady state . 19
6.5.10 Solar radiation (UV test) . 19
6.5.11 Solvents and contaminating fluids . 19
6.5.12 Salt mist and sulphur dioxide . 19
6.5.13 Water immersion . 19
6.5.14 Hygroscopicity . 19
6.5.15 Wicking . 19
6.5.16 Flame propagation characteristics of a single cable . 20
6.5.17 Flame propagation characteristics of bunched cables . 20
6.5.18 Halogen gas evolution . 20
6.5.19 Smoke generation. 20
6.5.20 Toxic gas emission . 20
6.5.21 Integrated fire test method for cables in environmental air handling
spaces . 20
7 Bundled cable requirements . 20
7.1 General . 20
7.2 Single pairs sharing one sheath . 20
7.2.1 General . 20
7.2.2 Near-end crosstalk (NEXT) . 20
7.2.3 Attenuation to crosstalk ratio far-end (PS ACR-F) . 21
Annex A (informative) Blank detail specification . 22
Annex B (informative) Background information for coupling attenuation and low
frequency coupling attenuation requirements . 27
Bibliography . 28

Table 1 – Transfer impedance . 11
Table 2 – Coupling attenuation . 11
Table 3 – Low frequency coupling attenuation . 12
Table 4 – Attenuation equation constants . 13
Table 5 – TCL requirements . 14
Table 6 – EL TCTL requirements . 14
Table 7 – PS ANEXT requirements . 15
Table 8 – PS AACR-F requirements . 15
Table 9 – RL requirements . 17
Table 10 – NEXT and PS NEXT requirements . 21
Table 11 – ACR-F and PS ACR-F requirements . 21
Table A.1 – Blank detail specification. 23

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MULTICORE AND SYMMETRICAL PAIR/QUAD CABLES
FOR DIGITAL COMMUNICATIONS –
Part 12: Symmetrical single pair cables with transmission characteristics
up to 600 MHz 1,25 GHz – Work area wiring – Sectional specification

FOREWORD
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6) All users should ensure that they have the latest edition of this publication.
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
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the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
This redline version of the official IEC Standard allows the user to identify the changes
made to the previous edition IEC 61156-12:2021. A vertical bar appears in the margin
wherever a change has been made. Additions are in green text, deletions are in
strikethrough red text.
IEC 61156-12 has been prepared by subcommittee 46C: Wires and symmetric cables, of IEC
technical committee 46: Cables, wires, waveguides, RF connectors, RF and microwave passive
components and accessories. It is an International Standard.
This second edition cancels and replaces the first edition published in 2021. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) additional cable type in support of T1-C generic single pair cabling up to 1,25 GHz;
b) introduction of low frequency coupling attenuation as an integral parameter describing
screening efficiency at frequencies below 30 MHz.
The text of this International Standard is based on the following documents:
Draft Report on voting
46C/1302/CDV 46C/1315/RVC
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts in the IEC 61156 series, published under the general title Multicore and
symmetrical pair/quad cables for digital communications, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
1 Scope
This part of IEC 61156 specifies cables intended to be used for transmission of 1 Gbit/s over a
single twisted balanced pair cabling for office, home and industrial application described in
ISO/IEC 11801-1:2017 and ISO/IEC 11801-1:2017/AMD1 . An example of existing application
is 1000BASE-T1, see ISO/IEC TR 11801-9906. The transmission characteristics of these
cables are specified up to a frequency of 600 MHz 1,25 GHz and at a temperature of 20 °C.
The cable type recognised is intended to be used for the work area wiring of shielded channels
with a nominal length of 40 m. Possible designs are U/FTP, X/UTP and X/FTP, where X stands
for F, S or SF. The T1-B type cable is specified from 0,1 MHz to 600 MHz, the T1-C type cable
from 0,1 MHz to 1,25 GHz. Depending on the MICE environment and the installation conditions,
either unscreened or screened cables can be used. A blank detail specification can be found in
Annex A.
These cables can comprise more than one pair in the event that several systems are operated
in parallel. In this case, refer to Clause 7.
The cables covered by this document are intended to operate with voltages and currents
normally encountered in communication systems. While these cables are not intended to be
used in conjunction with low impedance sources, for example the electric power supplies of
public utility mains, they are intended to be used to support the delivery of low-voltage remote
powering applications.
Annex A provides a blank detail specification (BDS) that can be used to summarize design and
performance requirements agreed upon between the supplier and the user of a specific cable
type.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60708, Low-frequency cables with polyolefin insulation and moisture barrier polyolefin
sheath
IEC 61156-1:2007, Multicore and symmetrical pair/quad cables for digital communications –
Part 1: Generic specification
IEC 61156-1:2007/AMD1:2009
IEC 61156-6, Multicore and symmetrical pair/quad cables for digital communications – Part 6:
Symmetrical pair/quad cables with transmission characteristics up to 1 000 MHz – Work area
wiring – Sectional specification
IEC 62153-4-3, Metallic communication cable test methods – Part 4-3: Electromagnetic
compatibility (EMC) – Surface transfer impedance – Triaxial method
IEC 62153-4-5, Metallic communication cables test methods – Part 4-5: Electromagnetic
compatibility (EMC) – Screening or coupling attenuation – Absorbing clamp method
___________
Under preparation. Stage at the time of publication: ISO/IEC/CCDV 11801-1:2024.
A consolidated edition 3.1 of this publication exists, comprising IEC 61156-1:2007 and IEC 61156-
1:2007/AMD1:2009.
IEC 62153-4-9:2018, Metallic communication cable test methods – Part 4-9: Electromagnetic
compatibility (EMC) – Coupling attenuation of screened balanced cables, triaxial method
IEC 62153-4-9:2018/AMD1:2020
ISO/IEC TS 29125:2017, Information technology – Telecommunications cabling requirements
for remote powering of terminal equipment
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61156-1:2007 and in
IEC 61156-1:2007/AMD1:2009 apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
4 Installation considerations
4.1 General remarks
rea considerations are defined in IEC 61156-1:2007. Other areas may be
Installation a
considered.
4.2 Bending radius of installed cable
The maximum value of The minimum bending radius shall be four times the cable diameter
unless otherwise specified.
The minimum bending radius of the cable shall be equal to or less than four times the outside
diameter of the cable unless otherwise specified, for example in case of armoured cables to
take their limited flexibility into account.
4.3 Climatic conditions
Under static conditions, the cable shall operate at least in the temperature range of the
environment from −20 °C to +60 °C.
The attenuation increase due to the elevated operating temperature (temperature of the
environment) is described in 6.3.3.2.
In the case of application of remote powering, the maximum temperature of the conductor shall
not exceed the maximum operation temperature under static conditions (60 °C) in order to
maintain the integrity of the dielectric material performance which is aligned to the
environmental temperature range.
Extended temperature ranges are permitted and may shall be specified in the relevant detail
specification.
5 Materials and cable construction
5.1 General remarks
For the purposes of this document, the requirements of IEC 61156-6 apply.
The choice of materials and cable construction shall be suitable for the intended application
and installation of the cable and in line with the requirements of IEC 61156-1:2007. Particular
care shall be taken to meet Ensure that any requirements for EMC and fire performance (such
as burning properties, smoke generation, evolution of halogen gas) are met. Regional
regulations can apply as well.
5.2 Cable construction
The cable construction shall be in accordance with the details and dimensions given in the
relevant detail specification.
5.3 Conductor
The conductor shall be a stranded or solid annealed copper conductor in accordance with 5.2.1
the requirements of IEC 61156-1:2007 and should have a nominal diameter between 0,4 mm
and 0,65 mm. A conductor diameter of up to 1,0 1,05 mm may be used.
NOTE The conductor dimensions seen in practice are wider than those dimensions that correspond to the resistance
requirements according to 6.2.1 and are therefore relevant for the design of the contact terminals of connecting
hardware.
5.4 Insulation
The conductor shall be insulated with a suitable material. Examples of suitable materials are
– polyolefin,
– fluoropolymer, and
– low-smoke zero-halogen-free thermoplastic material.
The colour code shall be in accordance with IEC 60708 if not specified differently in the relevant
detail specification.
5.5 Cable element
The cable element shall be a pair and shall be balanced twisted pair. The entire cable may
comprise more than one cable element, see 6.3.5 and Clause 7.
5.6 Screening of the cable element
When required, the screen for the cable element shall be in accordance with 5.2.3.2 of
IEC 61156-1:2007.
The screen of the cable element (if exists) shall be in accordance with the requirements of
IEC 61156-1.
5.7 Cable make-up
Fillers or spacers may be used in the cable elements and to separate cable elements. The cable
elements and their screens, if they are screened, may be covered by an intermediate jacket.
This jacket shall be in accordance with 5.9. The core of the cable may be wrapped with a
protective layer of non-hygroscopic and non-wicking material.
5.8 Screening of the cable core
When required, a screen for the cable core shall be provided. the screen shall be in accordance
with 5.2.5 of IEC 61156-1:2007.
Screened cables can either have screened cable elements and no screen of the cable core or
unscreend cable elements and a screen of the cable core or screened cable elements and a
screen of the cable core. If present, the screen shall be in accordance with the requirements of
IEC 61156-1.
5.9 Sheath
The sheath material shall consist of a suitable material. Examples of suitable materials are
– polyolefin,
– PVC,
– fluoropolymer, and
– low-smoke zero-halogen-free thermoplastic material.
The sheath shall be continuous, having a thickness as uniform as possible. A non-metallic
ripcord may be provided. When provided, the ripcord shall be non-hygroscopic and non-wicking.
The colour of the sheath is not specified but it should be specified in the relevant detail
specification.
5.10 Identification
Each length of cable shall be identified as to the supplier and, when required, a traceability
code, using one or combination of the following methods:
– appropriately coloured threads or tapes;
– with a printed tape;
– printing on the cable core wrapping;
– marking on the sheath.
Additional markings, such as length marking or maximum specified frequency, are permitted. If
used, such markings shall refer to this document.
5.11 Finished cable
The finished cable shall be adequately protected for storage and shipment.
6 Characteristics and requirements
6.1 General remarks
Clause 6 lists the characteristics and minimum requirements of a cable complying with this
document. Test methods shall be in accordance with Clause 6 the requirements of
IEC 61156-1:2007 and IEC 61156-1:2007/AMD1:2009, except for the length of the cable under
test which shall be as specified in Clause 6.
The computed requirements in dB, rounded to one decimal place, shall be used to determine
compliance.
The tests for electrical characteristics in accordance with 6.2 shall be carried out on a cable
length of not less than 100 m, unless otherwise specified.
The tests for transmission characteristics in accordance with 6.3 shall be carried out on a cable
length of 100 m, unless otherwise specified. For a better accuracy in high frequencies, the cable
length may be reduced to 50 m unless the test is performed with very sensitive test equipment.
For T1-C type cables, a length of 50 m may be used to improve accuracy at high frequencies.
For measurements over a wide frequency range as required for T1-C type cable, a balun-less
measurement technique is recommended, see IEC TS 61156-1-2.
6.2 Electrical characteristics and tests
6.2.1 Conductor resistance
The maximum conductor resistance at or corrected to 20 °C shall not exceed 145 Ω/km.
6.2.2 Resistance unbalance
6.2.2.1 Resistance unbalance within a pair
The resistance unbalance shall not exceed 2,0 %.
6.2.2.2 Resistance unbalance between pairs
Not applicable.
If applicable, for example in the case of bundled cables (see Clause 7), the pair-to-pair
resistance unbalance shall not exceed 5,0 %.
6.2.3 Dielectric strength
There shall be no failures when a test is performed on a conductor/conductor and, where
screens are present, on a conductor/screen with 1,0 kV DC for 1 min or, alternatively, with
2,5 kV DC for 2 s. An AC voltage may be used. The AC voltage levels in these cases shall be
0,7 kV AC for 1 min or alternatively 1,7 kV AC for 2 s.
6.2.4 Insulation resistance
The test shall be performed on
– conductor/conductor, and
– conductor/screen (if exists).
The minimum insulation resistance at or corrected to 20 °C shall be not less than 5 000 MΩ km
when tested immediately after the dielectric strength test.
6.2.5 Mutual capacitance
The mutual capacitance is not specified but may be indicated in the relevant detail specification.
6.2.6 Capacitance unbalance
The maximum capacitance unbalance pair to ground shall not exceed 1 600 1 200 pF/km at a
frequency of 800 Hz or 1 000 Hz.
6.2.7 Transfer impedance
For screened cables, Two three grades of performance are recognised for transfer impedance.
The transfer impedance measured in accordance with IEC 62153--4--3 shall not exceed the
values of at least one grade shown in Table 1.
Table 1 – Transfer impedance
Frequency range Maximum surface transfer impedance
MHz mΩ/m
Grade 1 Grade 2
1 to 10 −0,176 0,301
Zf≤⋅15 ( ) Zf≤⋅50 ( )
t t
10 to 30 0,631
f
Z ≤⋅23, 392 ( f )
Z ≤⋅10
t
t
f is the frequency in MHz.
Maximum surface transfer impedance in mΩ/m
Frequency range f in
MHz
Grade 1 Grade 1b Grade 2
0,1 to 1 15 30 50
−0,176 −0,176 0,301
1 to 10
Zf≤ 15 Zf≤ 30 Zf≤ 50
( ) ( ) ( )
t t t
0,631
f f
Zf≤ 23,392
( )
10 to 20 t
Z ≤ 10 Z ≤ 20
t t
10 10
6.2.8 Coupling attenuation and low frequency coupling attenuation
Three performance types for coupling attenuation are recognised. Coupling attenuation shall
be measured using either the absorbing clamp method (IEC 62153-4-5) or the triaxial method
for screened cables (IEC 62153-4-9). When measured using one of these methods, the coupling
attenuation in the frequency range from f = 30 MHz to 1 GHz for T1-B type cables or 1,25 GHz
for T1-C type cables shall meet the requirements of type I, type Ib or type II indicated in Table 2.
Table 2 – Coupling attenuation
Frequency range Coupling attenuation
Coupling
attenuation type
MHz dB
30 to 100 ≥ 85
Type I
100 to1 000 for T1-B type cables
≥ 85 – 20 log (f /100); f in MHz
100 to 1 000 1 250 for T1-C type cables
30 to 100 ≥ 70
Type Ib 100 to 1 000 for T1-B type cables
≥ 70 – 20 log (f /100); f in MHz
100 to 1 250 for T1-C type cables
30 to 100 ≥ 55
Type II
100 to 1 000 for T1-B type cables
≥ 55 – 20 log (f /100); f in MHz
100 to 1 250 for T1-C type cables

For frequencies below 30 MHz, three performance types for low frequency coupling attenuation
are recognised (see Table 3). Low frequency coupling attenuation shall be measured using the
triaxial method according to IEC 62153-4-9 in a tube of 3 m length. The requirements for low
frequency coupling attenuation are ffs.
Table 3 – Low frequency coupling attenuation
Frequency range Low frequency coupling attenuation
Low frequency coupling
attenuation type
MHz dB
≥ 85 – 10 log (f /30), 100 dB max. (ffs); f in MHz
Type I 0,1 to 30
≥ 70 – 10 log (f /30), 85 dB max. (ffs); f in MHz
Type Ib 0,1 to 30
≥ 55 – 10 log (f /30), 70 dB max. (ffs); f in MHz
Type II 0,1 to 30
Further details about the background of coupling attenuation versus low frequency coupling
attenuation requirements are given in Annex B.
NOTE Coupling attenuation and low frequency coupling attenuation requirements according to type II are not
applicable for MICE E3.
6.2.9 Current-carrying capacity
The maximum current-carrying capacity is installation dependent and therefore not specified
but may be indicated in the relevant detail specification. Further guidance with respect to current
carrying capacity is provided by ISO/IEC TS 29125:2017. The requirements with respect to
current-carrying capacity provided in ISO/IEC TS 29125 shall apply.
NOTE Local regulations can apply when supplying remote power.
6.3 Transmission characteristics
6.3.1 Velocity of propagation (phase velocity)
The requirements are not specified but may be indicated in the relevant detail specification.
6.3.2 Phase delay and differential delay (delay skew)
6.3.2.1 Phase delay
The phase delay, τ, shall not exceed the value obtained from Formula (1) in the frequency range
from 4 MHz to 600 MHz 0,1 MHz to 600 MHz for T1-B type cables or 1,25 GHz for T1-C type
cables. The requirements from 0,1 MHz to 1 MHz are ffs.
τ 534+
(1)
f
where
τ is the phase delay in ns/100 m;
f is the frequency in MHz.
6.3.2.2 Differential delay (delay skew)
If applicable, for example in the case of bundled cables (see Clause 7), the maximum delay
skew between any two pairs, when measured at (20 ± 3) °C, shall not exceed 25 ns/100 m in
the frequency range from 0,1 MHz to 600 MHz for T1-B type cables or 1,25 GHz for T1-C type
cables. The requirements from 0,1 MHz to 1 MHz are ffs.
=
6.3.3 Attenuation (α)
6.3.3.1 Attenuation at 20 °C operating temperature
The maximum attenuation, α, of any pair in the frequency range indicated in Table 4 shall not
exceed the value obtained from Formula (2). The requirements from 0,1 MHz to 1 MHz are ffs.
c
α a f+bf+
(2)
f
where
α is the attenuation expressed in dB/100 m;
a, b, c are constants indicated in Table 4;
f is the frequency expressed in MHz.
Table 4 – Attenuation equation constants
Frequency range Constants
MHz a b c
0,1 to 600 for T1-B type cables
2,7 0,007 5 0,375
0,1 to 1 250 for T1-C type cables

6.3.3.2 Attenuation at elevated operating temperature
The increase of the maximum attenuation from Formula (2) due to elevated environmental
temperature above 20 °C is obtained by calculation as follows:
– for unscreened cables: 0,4 %/°C in the temperature range from 20 °C to 40 °C and 0,6 %/°C
in the temperature range from 40 °C to 60 °C;
– for screened cables: 0,2 %/°C in the temperature range from 20 °C to 60 °C.
– for other types of screened cables where the cable elements are surrounded by an
intermediate sheath or bedding material: 0,4 %/°C, for the temperature range from 20 °C to
40 °C and 0,6 %/°C for the temperature range 40 °C to 60 °C.
In the event of application of remote powering, the actual conductor temperature should be
considered in order to calculate the attenuation increase. If an extended environmental
temperature range is specified (see 4.3), it is possible the temperature coefficients given in
6.3.3.2 are not applicable. The method provided in IEC 61156-1:2007 should be used to
determine temperature coefficients in this case.
6.3.4 Unbalance attenuation (TCL and EL TCTL)
The minimum near-end unbalance attenuation (transverse conversion loss (TCL)) shall not be
less than the value obtained from Table 5 in the frequency range from 0,1 MHz to 600 MHz for
T1-B type cables or 1,25 GHz for T1-C type cables. The requirements from 0,1 MHz to 1 MHz
are ffs.
=
Table 5 – TCL requirements
Frequency range TCL requirements
MHz dB
50 − 15 log (f); f in MHz;
1 to 600
40 dB maximum
TCL level Screened cables Unscreened cables
dB dB
40 – 15 log (f); f in MHz; 40 dB maximum 68 – 15 log (f); f in MHz; 53 dB maximum
10 10
Level 1
7 dB minimum 7 dB minimum
68 – 15 log (f); f in MHz; 53 dB maximum 68 – 15 log (f); f in MHz; 53 dB maximum
10 10
Level 2
7 dB minimum 7 dB minimum
68 – 15 log (f); f in MHz; 53 dB maximum 76 – 15 log (f); f in MHz; 53 dB maximum
10 10
Level 3
7 dB minimum 7 dB minimum
68 – 15 log (f); f in MHz; 53 dB maximum 84 – 15 log (f); f in MHz; 53 dB maximum
10 10
Level 4
7 dB minimum 7 dB minimum
The minimum equal-level far-end unbalance attenuation (equal-level transverse conversion
transfer loss (EL TCTL)) shall not be less than the value obtained from Table 6 in the frequency
range from 0,1 MHz to 600 MHz for T1-B type cables or 1,25 GHz for T1-C type cables. The
requirements from 0,1 MHz to 1 MHz are ffs.
Table 6 – EL TCTL requirements
Frequency range ELTCTL
MHz dB
40 − 20 log (f); f in MHz;
1 to 600
5 dB minimum
EL TCTL
Screened cables Unscreened cables
level
dB dB
40 − 20 log (f); f in MHz; 53 dB maximum 40 − 20 log (f); f in MHz; 53 dB maximum
10 10
Level 1
6 dB minimum 6 dB minimum
50 − 20 log (f); f in MHz; 53 dB maximum 50 − 20 log (f); f in MHz; 53 dB maximum
10 10
Level 2
6 dB minimum 6 dB minimum
60 − 20 log (f); f in MHz; 53 dB maximum 60 − 20 log (f); f in MHz; 53 dB maximum
10 10
Level 3
6 dB minimum 6 dB minimum
For calculation of EL TCTL, the TCTL and the attenuation measurement of the test specimen
with the same length as defined in 6.1 shall be used.
6.3.5 Alien (exogenous) near-end crosstalk (PS ANEXT)
The PS ANEXT (power-sum alien near-end crosstalk) of the cable when tested in accordance
with IEC 61156-1:2007 shall be not less than the values obtained from Table 7. The
requirements from 0,1 MHz to 1 MHz are ffs.
Table 7 – PS ANEXT requirements
Frequency range PS ANEXT
MHz dB
1 to 100 67
100 to 600 67
Cable type Frequency range PS ANEXT
MHz dB
T1-B type cables 0,1 to 100 70
70 − 10 log (f/100); f in MHz
100 to 600
T1-C type cables
0,1 to 100 75
75 − 10 log (f/100); f in MHz
100 to 1 250
For screened cables meeting the requirements of 6.2.7 and 6.2.8 (minimum type Ib) ANEXT is
proven by design (ffs).
6.3.6 Alien (exogenous) far-end crosstalk (PS AACR-F)
The PS AACR-F (power-sum alien attenuation to crosstalk ratio far-end) of the cable when
tested in accordance with IEC 61156-1:2007 shall not be less than the values obtained from
Table 8. The requirements from 0,1 MHz to 1 MHz are ffs.
For calculation of AACR-F, the AFEXT and the attenuation measurement of the test specimen
with a length as specified in 6.1 shall be used.
Table 8 – PS AACR-F requirements
Frequency range PS AACR-F
MHz dB
103 − 20 log (f); f in MHz
1 to 600
Cable type Frequency range PS AACR-F
MHz dB
T1-B type cables
98 − 20 log (f); f in MHz
0,1 to 600
T1-C type cables
103 − 20 log (f); f in MHz
0,1 to 1 250
If AFEXT up to 600 MHz is greater than 90 dB for T1-B type cables or greater than 90 dB up to
1 GHz and greater than 80 dB from 1 GHz to 1,25 GHz for T1-C type cables, the AACR-F may
not be calculated.
For those frequencies where the calculated limit value of PS AACR-F is greater than 80 75 dB
for T1-B type cables, the requirement shall be 80 75 dB.
For those frequencies where the calculated limit value of PS AACR-F is greater than 80 dB for
T1-C type cables, the requirement shall be 80 dB.
If AFEXT up to 600 MHz is greater than 90 dB, PS AACR-F may not be calculated.
For calculation of AACR-F, the AFEXT and the attenuation measurement of the test specimen
with the same length defined in 6.1 shall be used.
For screened cables meeting the requirements in accordance with 6.2.7 and 6.2.8 (minimum
Type Ib), AFEXT is proven by design.
6.3.7 Alien (exogenous) crosstalk of bundled cables
The relevant requirements of this document – especially those of 6.3.5 and 6.3.6 – apply; see
also Clause 7.
6.3.8 Impedance
The fitted or mean characteristic impedance measured in accordance with 6.3.10.2 or 6.3.10.3
of IEC 61156-1/AMD1:2009 IEC 61156-1 shall be 100 Ω ± 5 Ω at 100 MHz. A measurement of
the input impedance is not sufficient to ensure return loss li
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