IEC 61156-14:2025

IEC 61156-14 ®
Edition 1.0 2025-05
INTERNATIONAL
STANDARD
Multicore and symmetrical pair/quad cables for digital communications –
Part 14: Symmetrical single pair cables with transmission characteristics up to
20 MHz – Work area wiring – Sectional specification
ICS 33.120.20  ISBN 978-2-8327-0451-6

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– 2 – IEC 61156-14:2025 © IEC 2025
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
4 Installation considerations . 8
4.1 General remarks . 8
4.2 Bending radius of installed cable . 8
4.3 Climatic conditions . 8
5 Materials and cable construction . 8
5.1 General remarks . 8
5.2 Cable construction . 8
5.3 Conductor . 8
5.4 Insulation . 9
5.5 Cable element . 9
5.6 Screening of the cable element . 9
5.7 Cable make-up . 9
5.8 Screening of the cable core . 9
5.9 Sheath. 9
5.10 Identification . 9
5.11 Finished cable . 10
6 Characteristics and requirements . 10
6.1 General remarks . 10
6.2 Electrical characteristics and tests . 10
6.2.1 Conductor resistance . 10
6.2.2 Resistance unbalance within a pair . 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 . 11
6.2.8 Low frequency coupling attenuation . 11
6.2.9 Current-carrying capacity . 11
6.3 Transmission characteristics . 11
6.3.1 Velocity of propagation (phase velocity) . 11
6.3.2 Phase delay . 11
6.3.3 Attenuation (α) . 12
6.3.4 Unbalance attenuation (TCL and EL TCTL) . 13
6.3.5 Alien (exogenous) near-end crosstalk (PS ANEXT). 14
6.3.6 Alien (exogenous) far-end crosstalk (PS AACR-F) . 14
6.3.7 Impedance . 14
6.3.8 Return loss (RL) . 15
6.4 Mechanical and dimensional characteristics and requirements . 15
6.4.1 Dimensional requirements. 15
6.4.2 Elongation at break of the conductors . 15
6.4.3 Tensile strength of the insulation . 15
6.4.4 Elongation at break of the insulation . 15

6.4.5 Adhesion of the insulation to the conductor . 15
6.4.6 Elongation at break of the sheath . 15
6.4.7 Tensile strength of the sheath . 16
6.4.8 Crush test of the cable . 16
6.4.9 Impact test of the cable . 16
6.4.10 Bending under tension . 16
6.4.11 Repeated bending of the cable . 16
6.4.12 Tensile performance of the cable . 16
6.4.13 Shock test requirements of the cable . 16
6.4.14 Bump test requirements of the cable . 16
6.4.15 Vibration test requirements of a cable . 16
6.5 Environmental characteristics . 16
6.5.1 Shrinkage of insulation . 16
6.5.2 Wrapping test of insulation after thermal ageing . 16
6.5.3 Bending test of insulation at low temperature . 16
6.5.4 Elongation at break of the sheath after ageing . 17
6.5.5 Tensile strength of the sheath after ageing . 17
6.5.6 Sheath pressure test at high temperature . 17
6.5.7 Cold bend test of the cable . 17
6.5.8 Heat shock test . 17
6.5.9 Damp heat steady state . 17
6.5.10 Solar radiation (UV test) . 17
6.5.11 Solvents and contaminating fluids . 17
6.5.12 Salt mist and sulphur dioxide . 17
6.5.13 Water immersion . 17
6.5.14 Hygroscopicity . 17
6.5.15 Wicking . 17
6.5.16 Flame propagation characteristics of a single cable . 18
6.5.17 Flame propagation characteristics of bunched cables . 18
6.5.18 Halogen gas evolution . 18
6.5.19 Smoke generation . 18
6.5.20 Toxic gas emission. 18
6.5.21 Integrated fire test . 18
7 Bundled cables requirements . 18
8 Introduction to the blank detail specification (BDS) . 18

Annex A (informative) Blank detail specification . 19
Annex B (informative) Background information for coupling attenuation and low
frequency coupling attenuation requirements . 24
Bibliography . 25

Table 1 – Transfer impedance . 11
Table 2 – Low frequency coupling attenuation . 11
Table 3 – Attenuation equation constants . 12
Table 4 – Attenuation temperature coefficients . 12

– 4 – IEC 61156-14:2025 © IEC 2025
Table 5 – TCL requirements . 13
Table 6 – EL TCTL requirements. 14
Table 7 – PS ANEXT requirements . 14
Table 8 – PS AACR-F requirements . 14
Table 9 – RL requirements . 15

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MULTICORE AND SYMMETRICAL PAIR/QUAD CABLES
FOR DIGITAL COMMUNICATIONS –
Part 14: Symmetrical single pair cables with transmission characteristics
up to 20 MHz – Work area wiring – Sectional specification

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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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.
IEC 61156-14 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.
The text of this International Standard is based on the following documents:
Draft Report on voting
46C/1296/CDV 46C/1313/RVC
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
– 6 – IEC 61156-14:2025 © IEC 2025
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.
MULTICORE AND SYMMETRICAL PAIR/QUAD CABLES
FOR DIGITAL COMMUNICATIONS –
Part 14: Symmetrical single pair cables with transmission characteristics
up to 20 MHz – Work area wiring – Sectional specification

1 Scope
This part of IEC 61156 specifies cables for work area wiring intended to be used for
transmission of 10 Mb/s over a single twisted pair in channels for distances of up to 1 km. The
transmission characteristics of these cables are specified up to a frequency of 20 MHz and at
a temperature of 20 °C. Depending on the MICE environment and the installation conditions,
either unscreened or screened cables can be used. Furthermore, to consider different maximum
transmission lengths, two sets of requirements are specified. The cable type A-1000W does not
have attenuation de-rating compared to the A-1000 type according to IEC 61156-13 and is a
design supporting up to 1 km channel length. The cable type A-400W has attenuation de-rating
compared to the A-400 type according to IEC 61156-13. A blank detail specification can be
found in Annex A.
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 DC low voltage
remote powering applications.
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, Multicore and symmetrical pair/quad cables for digital communications – Part 1:
Generic specification
IEC TS 61156-1-2, Multicore and symmetrical pair/quad cables for digital communications –
Part 1-2: Electrical transmission characteristics and test methods of symmetrical pair/quad
cables
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 62153-4-9:2018, 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/
IEC 62153-4-9:2018/AMD2:2024
– 8 – IEC 61156-14:2025 © IEC 2025
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61156-1 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
Installation area considerations are defined in IEC 61156-1. Other areas may be 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.
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.
When applications demand remote powering, the maximum temperature of the conductor shall
not exceed the maximum operating temperature of the cable. Dielectric performance can be
changed permanently due to over exposure of high temperatures.
Extended temperature ranges are permitted but can cause safety issues. It may be specified in
the relevant detail specification.
5 Materials and cable construction
5.1 General remarks
For the purposes of this document, the respective 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. Any additional
requirements for EMC and fire performance (such as burning properties, smoke generation,
volution of halogen gas) shall be 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
IEC 61156-1 and should have a nominal diameter between 0,4 mm and 1,3 mm.

5.4 Insulation
The conductor shall be insulated with a suitable material. Examples of suitable materials are:
– polyolefin,
– fluoropolymer, and
– low-smoke halogen-free thermoplastic material.
The colour code shall be in accordance with IEC 60708 if not specified differently in the
respective detail specification.
5.5 Cable element
The cable element shall be a balanced pair and shall be twisted. A third insulated wire may be
twisted together with the pair for earthing and grounding purpose.
5.6 Screening of the cable element
If screened, the screen of the cable element shall be in accordance with IEC 61156-1.
5.7 Cable make-up
Bedding material may be used in the cable element to separate the cable element from other
design elements (e.g. braid, armouring). The cable element and its screen 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
If screened, the screen of the cable core shall be in accordance with 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 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 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, are permitted. If used, such markings shall refer
to this document.
– 10 – IEC 61156-14:2025 © IEC 2025
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 IEC 61156-1, except for the length of the
cable under test which shall be as specified in 6.1. If balunless testing is used, it should be in
accordance with IEC TS 61156-1-2.
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.
6.2 Electrical characteristics and tests
6.2.1 Conductor resistance
The maximum conductor resistance at or corrected to 20 °C shall not exceed 23 Ω/km for cable
type A-1000W or 108,75 Ω/km for cable type A-400W.
6.2.2 Resistance unbalance within a pair
The resistance unbalance shall not exceed 2,0 %.
6.2.3 Dielectric strength
There shall be no failures when a test is performed on conductor/conductor and, where
screen(s) are present, 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, immediately after the dielectric strength test, shall be performed on
– conductor/conductor, and
– conductor/screen if screen(s) are present.
The minimum insulation resistance at 20 °C shall be not less than 5 GΩ·km.
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 pF/km at a
frequency of 800 Hz or 1 000 Hz.

IEC 61156
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