IEC 61156-1:2023

Multicore and symmetrical pair/quad cables for digital communications - Part 1: Generic specification

IEC 61156-1:2023 specifies the definitions, requirements and test methods of multicore, symmetrical pair and quad cables. This document is applicable to communication systems such as local area networks (LANs) and data communication cables. It is also applicable to cables used for industrial applications, customer premises wiring and generic cabling comprising installation cables and cables for work area wiring which are defined in ISO/IEC 11801 (all parts). 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 including but not restricted to Power over Ethernet as specified in ISO/IEC/IEEE 8802-3.

Câbles multiconducteurs à paires symétriques et quartes pour transmissions numériques - Partie 1: Spécification générique

L’IEC 61156-1:2023 spécifie les définitions, les exigences et les méthodes d’essai des câbles multiconducteurs, à paires symétriques et à quartes. Le présent document est applicable aux systèmes de transmission tels que les réseaux locaux (LAN) et les câbles de transmission de données. Il est aussi applicable aux câbles utilisés pour les applications industrielles, le câblage des locaux des clients et le câblage générique comprenant des câbles d’installation et des câbles destinés au câblage d’espaces de travail qui sont définis dans l’ISO/IEC 11801 (toutes les parties). Les câbles couverts par le présent document sont destinés à être exploités sous des tensions et courants rencontrés conventionnellement dans les systèmes de communication. Bien que ces câbles ne soient pas destinés à être utilisés en conjonction avec des sources de basse impédance, par exemple les alimentations électriques des réseaux de services publics, ils sont destinés à être utilisés pour prendre en charge les applications de téléalimentation basse tension, y compris notamment l’alimentation par Ethernet, comme spécifié dans l’ISO/IEC/IEEE 8802-3.

General Information

• Status: Published
• Publication Date: 13-Mar-2023
• 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: 14-Mar-2023
• Completion Date: 24-Feb-2023

Relations

• Revises: IEC 61156-1:2007/COR1:2015 - Corrigendum 1 - Multicore and symmetrical pair/quad cables for digital communications - Part 1: Generic specification
• Effective Date: 05-Sep-2023
• Revises: IEC 61156-1:2007 - Multicore and symmetrical pair/quad cables for digital communications - Part 1: Generic specification
• Effective Date: 05-Sep-2023
• Revises: IEC 61156-1:2007/AMD1:2009 - Amendment 1 - Multicore and symmetrical pair/quad cables for digital communications - Part 1: Generic specification
• Effective Date: 05-Sep-2023

Overview - IEC 61156-1:2023 (Multicore & symmetrical pair/quad cables)

IEC 61156-1:2023 is the fourth edition generic specification for multicore and symmetrical pair/quad cables for digital communications. It defines terminology, construction requirements and standardized test methods for communication cables used in LANs, data communication systems, industrial installations and customer premises wiring. The standard covers installation and work‑area cables defined in ISO/IEC 11801, and addresses cables intended to carry voltages and currents normally encountered in communications, including support for low‑voltage remote powering applications such as Power over Ethernet (PoE) (per ISO/IEC/IEEE 8802-3).

Key topics and technical requirements

The standard lays out comprehensive requirements and test procedures across these areas:

• Materials & cable construction
  • Conductor, insulation, cable elements, screening, sheath and identification.
• Electrical characteristics & tests
  • Conductor resistance, resistance unbalance, dielectric strength, insulation resistance, mutual capacitance and capacitance unbalance to earth.
  • Transfer impedance and coupling attenuation relevant to screened and unscreened designs.
  • Current‑carrying capacity for powered cabling.
• Transmission performance
  • Velocity of propagation, phase delay and delay skew (differential delay).
  • Attenuation, unbalance attenuation, characteristic impedance and return loss.
  • Crosstalk measurements: near‑end (NEXT), far‑end (FEXT), and alien (exogenous) crosstalk for bundled installations.
• Mechanical & environmental tests
  • Dimensional checks, tensile/elongation, bending, crush, impact, repeated bending, vibration and shock.
  • Ageing, damp heat, cold flex, solvent resistance, water immersion, flame propagation, halogen gas evolution, smoke and toxic gas emission.
• Test setups
  • Defined measurement configurations (baluns, termination, drum winding and bundling) to ensure repeatable lab verification.

Applications & who uses IEC 61156-1:2023

This standard is essential for:

• Cable manufacturers designing and qualifying multicore, pair and quad cables.
• Test laboratories performing standardized electrical, mechanical and environmental testing.
• Network designers and system integrators specifying cable performance for LANs, industrial Ethernet, structured cabling and PoE deployments.
• Procurement and compliance teams writing technical specifications and acceptance criteria.
• Standards developers and safety authorities coordinating cabling performance with building and fire codes.

Related standards

• ISO/IEC 11801 (generic cabling for customer premises wiring)
• ISO/IEC/IEEE 8802-3 (Power over Ethernet)
• Other parts of the IEC 61156 series (for specific constructions and performance classes)

By following IEC 61156-1:2023, stakeholders ensure consistent, testable cable performance for reliable digital communications and power‑over‑data applications.

Standards Content (Sample)

IEC 61156-1 ®
Edition 4.0 2023-03
REDLINE VERSION
INTERNATIONAL
STANDARD
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inside
Multicore and symmetrical pair/quad cables for digital communications –
Part 1: Generic specification
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IEC 61156-1 ®
Edition 4.0 2023-03
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Multicore and symmetrical pair/quad cables for digital communications –
Part 1: Generic specification
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 33.120.20 ISBN 978-2-8322-6666-3

– 2 – IEC 61156-1:2023 RLV © IEC 2023
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 10
4 Installation considerations . 16
5 Materials and cable construction . 16
5.1 General remarks . 16
5.2 Cable constructions . 16
5.2.1 General . 16
5.2.2 Conductor . 16
5.2.3 Insulation . 17
5.2.4 Cable element . 17
5.2.5 Cable make-up . 18
5.2.6 Screening of the cable core . 18
5.2.7 Sheath . 18
5.2.8 Identification . 19
5.2.9 Finished cable . 19
6 Characteristics and requirements . 19
6.1 General remarks – Test configurations . 19
6.2 Electrical characteristics and tests . 21
6.2.1 Conductor resistance . 21
6.2.2 Resistance unbalance. 21
6.2.3 Dielectric strength . 22
6.2.4 Insulation resistance . 22
6.2.5 Mutual capacitance . 22
6.2.6 Capacitance unbalance to earth. 22
6.2.7 Transfer impedance . 23
6.2.8 Coupling attenuation . 23
6.2.9 Current-carrying capacity . 23
6.3 Transmission characteristics . 23
6.3.1 General requirements . 23
6.3.2 Velocity of propagation (phase velocity) . 24
6.3.3 Phase delay and differential delay (delay skew) . 25
6.3.4 Attenuation . 26
6.3.5 Unbalance attenuation . 28
6.3.6 Near-end crosstalk . 36
6.3.7 Far-end crosstalk . 38
6.3.8 Alien (exogenous) near-end crosstalk . 42
6.3.9 Alien (exogenous) far-end crosstalk . 46
6.3.10 Alien (exogenous) crosstalk of bundled cables . 46
6.3.11 Impedance . 47
6.3.12 Return loss . 49
6.4 Mechanical and dimensional characteristics and requirements . 50
6.4.1 Measurement of dimensions . 50
6.4.2 Elongation at break of the conductor. 50
6.4.3 Tensile strength of the insulation . 50

6.4.4 Elongation at break of the insulation . 51
6.4.5 Adhesion of the insulation to the conductor . 51
6.4.6 Elongation at break of the sheath . 51
6.4.7 Tensile strength of the sheath . 51
6.4.8 Crush test of the cable . 51
6.4.9 Cold Impact test of the cable . 51
6.4.10 Bending under tension . 51
6.4.11 Repeated bending of the cable . 54
6.4.12 Tensile performance of the cable . 55
6.4.13 Shock test of the cable . 55
6.4.14 Bump test of the cable . 55
6.4.15 Vibration test of the cable . 55
6.5 Environmental characteristics . 55
6.5.1 Shrinkage of the insulation . 55
6.5.2 Wrapping test of the insulation after thermal ageing . 55
6.5.3 Bending test of the insulation at low temperature . 56
6.5.4 Elongation at break of the sheath after ageing . 56
6.5.5 Tensile strength of the sheath after ageing . 56
6.5.6 Sheath pressure test at high temperature . 56
6.5.7 Cold bend test of the cable . 56
6.5.8 Heat shock test . 57
6.5.9 Damp heat, steady state . 57
6.5.10 Solar radiation . 57
6.5.11 Solvents and contaminating fluids . 57
6.5.12 Salt mist and sulphur dioxide . 57
6.5.13 Water immersion . 57
6.5.14 Hygroscopicity . 57
6.5.15 Wicking. 57
6.5.16 Flame propagation characteristics of a single cable . 58
6.5.17 Flame propagation characteristics of bunched cables . 58
6.5.18 Resistance to fire test method . 59
6.5.19 Halogen gas evolution . 59
6.5.20 Smoke generation . 59
6.5.21 Toxic gas emission . 59
6.5.22 Integrated fire test method for cables in environmental air handling

spaces . 59
Annex A (informative) Acronyms for common cable constructions . 60
Bibliography . 62

Figure 1 – Resistor terminations in balun measurements . 20
Figure 2 – Test set-up for the measurement of attenuation, velocity of propagation and
phase delay . 26
Figure 3 – Test set-up for the measurement of the differential-mode loss of the baluns. 30
Figure 4 – Test set-up for the measurement of the common-mode loss of the baluns . 31
Figure 5 – Test set-up for unbalance attenuation at near end (TCL) . 33
Figure 6 – Test set-up for unbalance attenuation at far end (TCTL) . 34
Figure 7 – Test set-up for near-end crosstalk . 36
Figure 8 – Test set-up for far-end crosstalk . 39

– 4 – IEC 61156-1:2023 RLV © IEC 2023
Figure 9 – Test set-up for alien (exogenous) near-end crosstalk . 42
Figure 10 – Test assembly cross-section: six cables around one cable . 44
Figure 11 – Test assembly layout: six cables around one cable . 44
Figure 12 – Test set-up for characteristic impedance, terminated input impedance, and
return loss . 47
Figure 13 – U-bend test configuration . 52
Figure 14 – S-bend test configuration . 53
Figure 15 – Repeated bending test configuration . 54
Figure 16 – Wicking test configuration . 58
Figure 18 – Schematic diagram representing the position of the 9 cables on a wooden
drum .
Figure 19 – Arrangement of the cables on the drum .
Figure 20 – Preparation of one end .
Figure A.1 – Common cable construction examples . 61

Table 1 – Test balun performance characteristics . 29
Table A.1 – Cable construction acronyms . 60

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MULTICORE AND SYMMETRICAL PAIR/QUAD
CABLES FOR DIGITAL COMMUNICATIONS –

Part 1: Generic specification
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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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) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. 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 61156-1:2007+AMD1:2009 CSV. A vertical bar appears
in the margin wherever a change has been made. Additions are in green text, deletions
are in strikethrough red text.

– 6 – IEC 61156-1:2023 RLV © IEC 2023
IEC 61156-1 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 fourth edition cancels and replaces the third edition published in 2007 and Amendment 1
published in 2009. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) modification of the scope in Clause 1 and updating of normative references documents in
Clause 2;
b) addition of PoE-related definitions in Clause 3;
c) clarification of differential-mode and common-mode resistors, correction of formulae and
addition of IEC 62153-4-9 test method for coupling attenuation in Clause 6;
d) introduction of balunless measurement method in 6.3.1, modification of equipment
requirements of unbalance attenuation in 6.3.5 and updating of balun’s performance in
Table 1;
e) deletion of ‘three layers of cables on a drum’ method in alien (exogenous) near-end crosstalk
measurement in 6.3.8 and addition of terminated input impedance in 6.3.11.4.
The text of this International Standard is based on the following documents:
Draft Report on voting
46C/1242/FDIS 46C/1249/RVD
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 and French.
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/standardsdev/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,
• replaced by a revised edition, or
• amended.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates that it
contains colours which are considered to be useful for the correct understanding of its
contents. Users should therefore print this document using a colour printer.

MULTICORE AND SYMMETRICAL PAIR/QUAD
CABLES FOR DIGITAL COMMUNICATIONS –

Part 1: Generic specification
1 Scope
This part of IEC 61156 is applicable to communication systems such as ISDN, local area
networks and data communication systems and specifies the definitions, requirements and test
methods of multicore, symmetrical pair and quad cables.
This document is applicable to communication systems such as local area networks (LANs) and
data communication cables. It is also applicable to cables used for industrial applications,
customer premises wiring and generic cabling comprising installation cables and cables for
work area wiring which are defined in ISO/IEC 11801 (all parts).
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 including but not restricted to Power over Ethernet as specified in
ISO/IEC/IEEE 8802-3. More information on the capacity to support these applications according
to the installation practices are given in IEC 61156-1-4, IEC TR 61156-1-6 and
ISO/IEC TS 29125.
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 60028, International standard of resistance for copper
IEC 60050-726, International Electrotechnical Vocabulary (IEV) – Part 726: Transmission lines
and wave guides
IEC 60068-2-1:2007, Environmental testing – Part 2-1: Tests – Tests A: Cold
IEC 60169-22, Radio-frequency connectors – Part 22: RF two-pole bayonet coupled
connectors for use with shielded balanced cables having twin inner conductors (Type BNO)
IEC 60189-1:19862018, Low-frequency cables and wires with PVC insulation and PVC sheath
1)
– Part 1: General test and measuring methods
IEC 60304, Standard colours for insulation for low-frequency cables and wires
IEC 60332-1-1, Tests on electric and optical fibre cables under fire conditions – Part 1-1: Test
for vertical flame propagation for a single insulated wire or cable – Apparatus
___________
1)
There exists a 2007 edition of 60189-1.

– 8 – IEC 61156-1:2023 RLV © IEC 2023
IEC 60332-2-1, Tests on electric and optical fibre cables under fire conditions – Part 2-1: Test
for vertical flame propagation for a single small insulated wire or cable – Apparatus
IEC 60332-1-2, Tests on electric and optical fibre cables under fire conditions – Part 1-2: Test
for vertical flame propagation for a single insulated wire or cable – Procedure for 1 kW pre-
mixed flame
IEC 60332-2-2, Tests on electric and optical fibre cables under fire conditions – Part 2-2: Test
for vertical flame propagation for a single small insulated wire or cable – Procedure for diffusion
flame
IEC 60332-3-10, Tests on electric cables under fire conditions – Part 3-10: Test for vertical
flame spread of vertically-mounted bunched wires or cables – Apparatus
IEC 60332-3-24, Tests on electric and optical fibre cables under fire conditions – Part 3-24:
Test for vertical flame spread of vertically-mounted bunched wires or cables – Category C
IEC 60332-3-25, Tests on electric and optical fibre cables under fire conditions – Part 3-25:
Test for vertical flame spread of vertically-mounted bunched wires or cables – Category D
IEC 60708, Low-frequency cables with polyolefin insulation and moisture barrier polyolefin
sheath
IEC 60754-2, Test on gases evolved during combustion of electric materials from cables – Part
2: Determination of the degree of acidity of gases evolved during the combustion of materials
taken from electric cables by measuring pH and conductivity Determination of acidity (by pH
measurement) and conductivity
IEC 60794-1-2:2003, Optical fibre cables – Part 1-2: Generic specification – Basic optical
cable test procedures
IEC 60794-1-21:2015, Optical fibre cables – Part 1-21: Generic specification – Basic optical
cable test procedures – Mechanical test methods
IEC 60811-1-1:1993, Common test methods for insulating and sheathing materials of electric
cables and optical cables – Part 1: Methods for general application – Section 1: Measurement
of thickness and overall dimensions – Tests for determining the mechanical properties
IEC 60811-1-2:1985, Common test methods for insulating and sheathing materials of electric
and optical cables – Part 1: Methods for general application – Section Two: Thermal ageing
methods
IEC 60811-1-3:1993, Common test methods for insulating and sheathing materials of electric
and optical cables – Part 1: Methods for general application – Section Three: Methods for
determining the density – Water absorption tests – Shrinkage test
IEC 60811-1-4:1985, Common test methods for insulating and sheathing materials of electric
and optical cables – Part 1: Methods for general application – Section Four: Test at low
temperature
IEC 60811-3-1:1985, Common test methods for insulating and sheathing materials of electric
and optical cables – Part 3: Methods specific to PVC compounds – Section One: Pressure
test at high temperature – Tests for resistance to cracking
IEC 60811-4-2:2004, Insulating and sheathing materials of electric cables – Common test
methods – Part 4-2: Methods specific to polyethylene and polypropylene compounds –Tensile
strength and elongation at break after conditioning at elevated temperature – Wrapping test

after conditioning at elevated temperature – Wrapping test after thermal ageing in air –
Measurement of mass increase – Long-term stability test – Test method for copper-catalyzed
oxidative degradation
IEC 60811-201, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 201: General tests – Measurement of insulation thickness
IEC 60811-202, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 202: General tests – Measurement of thickness of non-metallic sheath
IEC 60811-203, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 203: General tests – Measurement of overall dimensions
IEC 60811-401, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 401: Miscellaneous tests – Thermal ageing methods – Ageing in an air oven
IEC 60811-501, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 501: Mechanical tests – Tests for determining the mechanical properties of insulating and
sheathing compounds
IEC 60811-502, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 502: Mechanical tests – Shrinkage test for insulations
IEC 60811-504, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 504: Mechanical tests – Bending tests at low temperature for insulation and sheaths
IEC 60811-506, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 506: Mechanical tests – Impact test at low temperature for insulations and sheaths
IEC 60811-508, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 508: Mechanical tests – Pressure test at high temperature for insulation and sheaths
IEC 60811-509, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 509: Mechanical tests – Test for resistance of insulations and sheaths to cracking (heat
shock test)
IEC 60811-510, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 510: Mechanical tests – Methods specific to polyethylene and polypropylene compounds
– Wrapping test after thermal ageing in air
IEC 61034 (all parts), Measurement of smoke density of cables burning under defined
conditions
IEC TR 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 TR 61156-1-5, Multicore and symmetrical pair/quad cables for digital communications –
Part 1-5: Correction procedures for the measurement results of return loss and input impedance
IEC 61196-1-105, Coaxial communication cables – Part 1-105: Electrical test methods – Test
for withstand voltage of cable dielectric
___________
IEC TR 61156-1-2 is due to become a TS in 2023.

– 10 – IEC 61156-1:2023 RLV © IEC 2023
IEC 62012-1:20042002, Multicore and symmetrical pair/quad cables for digital communications
to be used in harsh environments – Part 1: Generic specification
IEC 62153-4-3:2013, Metallic communication cables test methods – Part 4-3: Electromagnetic
compatibility (EMC) – Surface transfer impedance – Triaxial method
IEC 62153-4-4, Metallic communication cables test methods – Part 4-4: Electromagnetic
compatibility (EMC) – Shielded screening attenuation, test method for measuring of the
screening attenuation a up to and above 3 GHz
s
IEC 62153-4-5, Metallic communication cables test methods – Part 4-5: Electromagnetic
compatibility (EMC) – Coupling or screening Screening or coupling attenuation – Absorbing
clamp method
IEC 62153-4-9, Metallic communication cable test methods – Part 4-9: Electromagnetic
compatibility (EMC) – Coupling attenuation of screened balanced cables, triaxial method
IEC 62255 (all parts), Multicore and symmetrical pair/quad cables for broadband digital
communications (high bit rate digital access telecommunication networks) – Outside plant
cables
ISO/IEC TS 29125:2017, Information technology – Telecommunications cabling requirements
for remote powering of terminal equipment
ITU-T Recommendation G.117:1996, Transmission aspects of unbalance about earth
ITU-T Recommendation O.9:1999, Measuring arrangements to assess the degree of unbalance
about earth
3 Terms and definitions
For the purposes of this document, the following terms and definitions, as well as those given
in IEC 60050-726, 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
3.1
resistance unbalance
difference in resistance of the conductors within a pair or one side of a quad or between pairs
or quads
Note 1 to entry: Resistance unbalance is expressed as a percentage (%).
3.2
mutual capacitance
electrical charge storage parameter of a pair of conductors (or with respect to the side of a
quad)
Note 1 to entry: Mutual capacitance is one of the four primary transmission line parameters: mutual capacitance,
mutual inductance, resistance and conductance.
Note 2 to entry: Mutual capacitance is expressed in pF/m.

3.3
capacitance unbalance to earth
arithmetic difference of the capacitance to earth of the conductors of a pair or one side of a
quad
Note 1 to entry: Capacitance unbalance is expressed in pF/m.
3.4
screen
continuous conducting layer or assembly of conducting layers having the function of reducing
the penetration of an electric, magnetic or electromagnetic field into a given region
[SOURCE: IEC 60050-195:2021,195-02-37, modified – "continuous conducting layer or
assembly of conducting layers having the function of reducing " has replaced "device intended
to reduce "]
3.5
balun
balanced to unbalanced impedance matching transformer
device to provide impedance transformation between balanced and unbalanced components
[SOURCE:ISO/IEC 11801-4:2017, 3.1.2]
3.6
balunless
virtual balun used instead of the physical transformers, achieved by mathematical algorithm,
and calculated from lumped parameters or distributed parameter network
3.7
transfer impedance
Z
T
quotient of the longitudinal voltage of an electrically short uniform cable, induced in the outer
circuit – formed by the screen under test and the measuring jig – and the current fed into the
inner circuit – the cable under test itself or vice versa, related to unit length
Note 1 to entry: Transfer impedance is expressed in mΩ/m.
[SOURCE: IEC 62153-4-3:2013, 3.3, modified – "of an electrically short uniform cable" has
been added, "outer circuit" has replaced “matched outer circuit", “the cable under test itself"
has been added, “related to unit length" has replaced "(see Figure 1)".]
3.8
coupling attenuation
a
c
ratio between the transmitted power through the conductors and the maximum radiated peak
power, conducted and generated by the exited common-mode currents
for a screened balanced cable, the sum of the effects of the unbalance attenuation a of the
U
symmetric pair and the screening attenuation α of the screen of the cable under test
s
Note 1 to entry: For electrically long devices, i.e. above the cut-off frequency, the coupling attenuation α is defined
C
as the logarithmic ratio of the feeding power P and the periodic maximum values of the coupled power P in the
1 r, max
outer circuit.
Note 2 to entry: Coupling attenuation is expressed in dB.
[SOURCE: IEC 62153-4-7:2021, 3.4, modified –“cable" has replaced “device", “sum of the
effects’" has replaced “sum", Note 2 has been added.]

– 12 – IEC 61156-1:2023 RLV © IEC 2023
3.9
current carrying capacity
maximum current a cable circuit (one or several conductors) can support resulting in a specified
increase of the surface temperature of the conductor beyond the ambient temperature, not
exceeding the maximum allowed operating temperature of the cable
3.10
velocity of propagation
(phase velocity)
speed at which a sinusoidal signal propagates on a pair in the cable
Note 1 to entry: Velocity of propagation is expressed in m/s.
3.11
(phase delay)
delay
time duration between the instants that the wave front of a sinusoidal travelling wave, defined
by a specified phase, passes two given points in a cable
Note 1 to entry: Phase delay is expressed in s/m.
3.12
differential phase delay
(delay skew)
difference in phase delay between any two pairs in the cable
Note 1 to entry: Differential phase delay (skew) is expressed in s.
3.13
attenuation
decrease in magnitude of power of a signal that propagates along a pair of a cable
Note 1 to entry: Attenuation is expressed in dB/m.
3.14
ambient temperature
temperature of the room or space surrounding the cable
Note 1 to entry: Ambient temperature is expressed in degree Celsius (°C).
3.15
operating temperature
surface temperature of the conductors of a cable
Note 1 to entry: The operating temperature is the sum of the ambient temperature and of the temperature increase
due to the carried power.
Note 2 to entry: Operating temperature is expressed in degree Celsius (°C).
3.16
unbalance attenuation
UA
magnitude of power of a signal that propagates between the common-mode circuit and the
differential-mode circuit of a cable
logarithmic ratio of the differential mode power to the common mode power in a balanced line,
or vice versa
Note 1 to entry: Unbalance attenuation is expressed in dB.
Note 2 to entry: Unbalance attenuation is also often referred to as conversion loss: TCL (transverse conversion
loss), TCTL (transverse conversion transfer loss), LCL (longitudinal conversion loss), LCTL (longitudinal conversion

transfer loss), EL TCTL (equal level transverse conversion transfer loss) and EL LCTL (equal level longitudinal
conversion loss transfer loss).
3.17
transverse conversion loss
TCL
logarithmic ratio of the differential-mode circuit power at the near end and the common-mode
coupling power measured at the near end
3.18
equal level transverse conversion transfer loss
EL TCTL
output-to-output measurement of the logarithmic ratio of the differential-mode circuit power at
the near end and the common-mode coupling power measured at the far end
Note 1 to entry: EL TCTL is calculated by the difference between the measured TCTL and the differential-mode
insertion loss of the disturbed pair.
3.19
near-end crosstalk
NEXT
magnitude of the signal power coupling from a disturbing pair at the near end to a disturbed
pair measured at the near end
Note 1 to entry: Near-end crosstalk is expressed in dB.
3.20
far-end crosstalk
FEXT
magnitude of the signal power coupling from a disturbing pair at the near end to a disturbed
pair measured at the far end
Note 1 to entry: Far-end crosstalk is expressed in dB.
3.21
power sum of crosstalk
PS
summation of the crosstalk power from all disturbing pairs into a disturbed pair
Note 1 to entry: The summation is applicable to near-end and far-end crosstalk.
Note 2 to entry: The power sum of crosstalk is expressed in dB.
3.12
attenuation to crosstalk ratio, near-end
ACR-N
arithmetic difference between the near-end crosstalk and the attenuation of the disturbed pair
NOTE Attenuation to crosstalk ratio, near-end, is expressed in dB.
3.22
attenuation to crosstalk ratio, far-end
ACR-F
arithmetic difference between the far-end crosstalk and the attenuation of the disturbed pair
Note 1 to entry: Attenuation to crosstalk ratio, far-end, is expressed in dB.
3.23
alien (exogenous) near-end crosstalk
ANEXT
near-end crosstalk where the disturbing and disturbed pairs are contained in different cables

– 14 – IEC 61156-1:2023 RLV © IEC 2023
Note 1 to entry: Alien (exogenous) near-end crosstalk is expressed in dB.
3.24
alien (exogenous) far-end crosstalk
AFEXT
far-end crosstalk where the disturbing and disturbed pairs are contained in different cables
Note 1 to entry: Alien (exogenous) far-end crosstalk is expressed in dB.
3.25
alien (exogenous) far-end crosstalk
AACR-F
far-end crosstalk where the disturbing and disturbed pairs are contained in different cables
Note 1 to entry: Alien (exogenous) far-end crosstalk is expressed in dB.
3.26
power sum of alien (exogenous) near-end crosstalk
PSA
PS ANEXT
summation of the near-end alien (exogenous) crosstalk power from all disturbing pairs into a
disturbed pair in different cables
Note 1 The summation is applicable to near-end and far-end alien (exogenous) crosstalk.
Note 1 to entry: The power sum of alien (exogenous) near-end crosstalk is expressed in dB.
3.27
power sum of alien (exogenous) far-end crosstalk
PS AACR-F
summation of the alien (exogenous) far-end crosstalk power from all disturbing pairs into a
disturbed pair in different cables
Note 1 to entry: The power sum of far-end alien (exogenous) crosstalk is expressed in dB.
3.28
characteristic impedance
Z
C
impedance at the input of a homogeneous line of infinite length
Note 1 to entry: The impedance value is expressed in Ω, calculated at relevant frequencies, as the square root of
the product of the impedance measured at the near end (input) of a cable pair when the far end is terminated by a
short- an open circuit load and then an open- short circuit load.
Note 2 to entry: The asymptotic value at high frequencies is denoted as Z .
∞
Note 3 to entry: The characteristic impedance of a homogeneous cable pair is given by the quotient of a voltage
wave and current wave which are propagating in the same direction, either forwards or backwards.
Note 4 to entry: For homogeneous ideal cables, this test method yields a flat smooth curve over the whole frequency
range. Real cables with distortions give curves with some roughness.
3.29
terminated input impedance
Z
in
impedance value, expressed in Ω, at relevant frequencies, measured at the near end (input)
when the far end is terminated with the system nominal impedance, Z
R
(See IEC/TR 62152.)
3.30
fitted characteristic impedance
Z
m
impedance value, expressed in Ω, calculated by applying a least squares function fitting
algorithm to the measured characteristic impedance values
3.31
mean characteristic impedance
Z
∞
asymptotic value at which the characteristic impedance approaches at sufficiently high
frequencies (≈100 MHz) such that the imaginary part (phase angle) is insignificant
Note 1 to entry: Normally measured from the capacitance and time delay.
Note 2 to entry: Applicable for cables with frequency independence of mutual capacitance.
3.32
return loss
RL
ratio of reflected power to input power at the input terminals of a cable pair
Note 1 to entry: Return loss is expressed in dB.
3.33
bundled cable
grouping or assembly of several individual cables that are systematically laid up
Note 1 to entry: Bundled cables are also referred to as speed-wrap, whip, or loomed cables.
3.34
remote powering
supply of power to application specific equipment via balanced cabling
[SOURCE: ISO/IEC TS 29125:2017, 3.1.5]
3.35
safety extra-low voltage
SELV
AC voltage the RMS value of which does not exceed 50 V or ripple-free DC voltage the value
of which does not exceed 120 V, between conductors, or between any conductor and reference
earth, in an electric circuit which has galvanic separation from the supplying electric power
system by such means as a separate-winding transformer
Note 1 to entry: Maximum voltage lower than 50 V AC or 120 V ripple-free DC may be specified in particular
requirements, especially when direct contact with live parts is allowed.
Note 2 to entry: The voltag
...

IEC 61156-1 ®
Edition 4.0 2023-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Multicore and symmetrical pair/quad cables for digital communications –
Part 1: Generic specification
Câbles multiconducteurs à paires symétriques et quartes pour transmissions
numériques –
Partie 1: Spécification générique

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IEC 61156-1 ®
Edition 4.0 2023-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Multicore and symmetrical pair/quad cables for digital communications –

Part 1: Generic specification
Câbles multiconducteurs à paires symétriques et quartes pour transmissions

numériques –
Partie 1: Spécification générique

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.120.20 ISBN 978-2-8322-6373-0

– 2 – IEC 61156-1:2023 © IEC 2023
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 9
4 Installation considerations . 14
5 Materials and cable construction . 15
5.1 General remarks . 15
5.2 Cable constructions . 15
5.2.1 General . 15
5.2.2 Conductor . 15
5.2.3 Insulation . 15
5.2.4 Cable element . 16
5.2.5 Cable make-up . 16
5.2.6 Screening of the cable core . 17
5.2.7 Sheath . 17
5.2.8 Identification . 17
5.2.9 Finished cable . 18
6 Characteristics and requirements . 18
6.1 General remarks – Test configurations . 18
6.2 Electrical characteristics and tests . 19
6.2.1 Conductor resistance . 19
6.2.2 Resistance unbalance. 19
6.2.3 Dielectric strength . 20
6.2.4 Insulation resistance . 20
6.2.5 Mutual capacitance . 20
6.2.6 Capacitance unbalance to earth. 20
6.2.7 Transfer impedance . 21
6.2.8 Coupling attenuation . 21
6.2.9 Current-carrying capacity . 21
6.3 Transmission characteristics . 21
6.3.1 General requirements . 21
6.3.2 Velocity of propagation (phase velocity) . 22
6.3.3 Phase delay and differential delay (delay skew) . 23
6.3.4 Attenuation . 23
6.3.5 Unbalance attenuation . 26
6.3.6 Near-end crosstalk . 32
6.3.7 Far-end crosstalk . 34
6.3.8 Alien (exogenous) near-end crosstalk . 36
6.3.9 Alien (exogenous) far-end crosstalk . 39
6.3.10 Alien (exogenous) crosstalk of bundled cables . 39
6.3.11 Impedance . 40
6.3.12 Return loss . 42
6.4 Mechanical and dimensional characteristics and requirements . 43
6.4.1 Measurement of dimensions . 43
6.4.2 Elongation at break of the conductor. 43
6.4.3 Tensile strength of the insulation . 43

6.4.4 Elongation at break of the insulation . 43
6.4.5 Adhesion of the insulation to the conductor . 43
6.4.6 Elongation at break of the sheath . 43
6.4.7 Tensile strength of the sheath . 43
6.4.8 Crush test of the cable . 43
6.4.9 Cold Impact test of the cable . 43
6.4.10 Bending under tension . 44
6.4.11 Repeated bending of the cable . 46
6.4.12 Tensile performance of the cable . 47
6.4.13 Shock test of the cable . 47
6.4.14 Bump test of the cable . 47
6.4.15 Vibration test of the cable . 48
6.5 Environmental characteristics . 48
6.5.1 Shrinkage of the insulation . 48
6.5.2 Wrapping test of the insulation after thermal ageing . 48
6.5.3 Bending test of the insulation at low temperature . 48
6.5.4 Elongation at break of the sheath after ageing . 48
6.5.5 Tensile strength of the sheath after ageing . 48
6.5.6 Sheath pressure test at high temperature . 48
6.5.7 Cold bend test of the cable . 48
6.5.8 Heat shock test . 49
6.5.9 Damp heat, steady state . 49
6.5.10 Solar radiation . 49
6.5.11 Solvents and contaminating fluids . 49
6.5.12 Salt mist and sulphur dioxide . 49
6.5.13 Water immersion . 49
6.5.14 Hygroscopicity . 49
6.5.15 Wicking. 50
6.5.16 Flame propagation characteristics of a single cable . 50
6.5.17 Flame propagation characteristics of bunched cables . 51
6.5.18 Resistance to fire test method . 51
6.5.19 Halogen gas evolution . 51
6.5.20 Smoke generation . 51
6.5.21 Toxic gas emission . 51
6.5.22 Integrated fire test method for cables in environmental air handling

spaces . 51
Annex A (informative) Acronyms for common cable constructions . 52
Bibliography . 54

Figure 1 – Resistor terminations in balun measurements . 19
Figure 2 – Test set-up for the measurement of attenuation, velocity of propagation and
phase delay . 24
Figure 3 – Test set-up for the measurement of the differential-mode loss of the baluns. 28
Figure 4 – Test set-up for the measurement of the common-mode loss of the baluns . 28
Figure 5 – Test set-up for unbalance attenuation at near end (TCL) . 30
Figure 6 – Test set-up for unbalance attenuation at far end (TCTL) . 30
Figure 7 – Test set-up for near-end crosstalk . 32
Figure 8 – Test set-up for far-end crosstalk . 34

– 4 – IEC 61156-1:2023 © IEC 2023
Figure 9 – Test set-up for alien (exogenous) near-end crosstalk . 37
Figure 10 – Test assembly cross-section: six cables around one cable . 39
Figure 11 – Test assembly layout: six cables around one cable . 39
Figure 12 – Test set-up for characteristic impedance, terminated input impedance, and
return loss . 40
Figure 13 – U-bend test configuration . 45
Figure 14 – S-bend test configuration . 45
Figure 15 – Repeated bending test configuration . 46
Figure 16 – Wicking test configuration . 50
Figure A.1 – Common cable construction examples . 53

Table 1 – Test balun performance characteristics . 26
Table A.1 – Cable construction acronyms . 52

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MULTICORE AND SYMMETRICAL PAIR/QUAD
CABLES FOR DIGITAL COMMUNICATIONS –

Part 1: Generic specification
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
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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) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC 61156-1 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 fourth edition cancels and replaces the third edition published in 2007 and Amendment 1
published in 2009. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) modification of the scope in Clause 1 and updating of normative references documents in
Clause 2;
b) addition of PoE-related definitions in Clause 3;
c) clarification of differential-mode and common-mode resistors, correction of formulae and
addition of IEC 62153-4-9 test method for coupling attenuation in Clause 6;

– 6 – IEC 61156-1:2023 © IEC 2023
d) introduction of balunless measurement method in 6.3.1, modification of equipment
requirements of unbalance attenuation in 6.3.5 and updating of balun’s performance in
Table 1;
e) deletion of ‘three layers of cables on a drum’ method in alien (exogenous) near-end crosstalk
measurement in 6.3.8 and addition of terminated input impedance in 6.3.11.4.
The text of this International Standard is based on the following documents:
Draft Report on voting
46C/1242/FDIS 46C/1249/RVD
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 and French.
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/standardsdev/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,
• replaced by a revised edition, or
• amended.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates that it
contains colours which are considered to be useful for the correct understanding of its
contents. Users should therefore print this document using a colour printer.

MULTICORE AND SYMMETRICAL PAIR/QUAD
CABLES FOR DIGITAL COMMUNICATIONS –

Part 1: Generic specification
1 Scope
This part of IEC 61156 specifies the definitions, requirements and test methods of multicore,
symmetrical pair and quad cables.
This document is applicable to communication systems such as local area networks (LANs) and
data communication cables. It is also applicable to cables used for industrial applications,
customer premises wiring and generic cabling comprising installation cables and cables for
work area wiring which are defined in ISO/IEC 11801 (all parts).
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 including but not restricted to Power over Ethernet as specified in
ISO/IEC/IEEE 8802-3. More information on the capacity to support these applications according
to the installation practices are given in IEC 61156-1-4, IEC TR 61156-1-6 and
ISO/IEC TS 29125.
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 60028, International standard of resistance for copper
IEC 60068-2-1:2007, Environmental testing – Part 2-1: Tests – Tests A: Cold
IEC 60189-1:2018, Low-frequency cables and wires with PVC insulation and PVC sheath –
Part 1: General test and measuring methods
IEC 60304, Standard colours for insulation for low-frequency cables and wires
IEC 60332-1-2, Tests on electric and optical fibre cables under fire conditions – Part 1-2: Test
for vertical flame propagation for a single insulated wire or cable – Procedure for 1 kW pre-
mixed flame
IEC 60332-2-2, Tests on electric and optical fibre cables under fire conditions – Part 2-2: Test
for vertical flame propagation for a single small insulated wire or cable – Procedure for diffusion
flame
IEC 60332-3-24, Tests on electric and optical fibre cables under fire conditions – Part 3-24:
Test for vertical flame spread of vertically-mounted bunched wires or cables – Category C
IEC 60332-3-25, Tests on electric and optical fibre cables under fire conditions – Part 3-25:
Test for vertical flame spread of vertically-mounted bunched wires or cables – Category D

– 8 – IEC 61156-1:2023 © IEC 2023
IEC 60708, Low-frequency cables with polyolefin insulation and moisture barrier polyolefin
sheath
IEC 60754-2, Test on gases evolved during combustion of materials from cables – Part 2:
Determination of acidity (by pH measurement) and conductivity
IEC 60794-1-21:2015, Optical fibre cables – Part 1-21: Generic specification – Basic optical
cable test procedures – Mechanical test methods
IEC 60811-201, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 201: General tests – Measurement of insulation thickness
IEC 60811-202, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 202: General tests – Measurement of thickness of non-metallic sheath
IEC 60811-203, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 203: General tests – Measurement of overall dimensions
IEC 60811-401, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 401: Miscellaneous tests – Thermal ageing methods – Ageing in an air oven
IEC 60811-501, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 501: Mechanical tests – Tests for determining the mechanical properties of insulating and
sheathing compounds
IEC 60811-502, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 502: Mechanical tests – Shrinkage test for insulations
IEC 60811-504, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 504: Mechanical tests – Bending tests at low temperature for insulation and sheaths
IEC 60811-506, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 506: Mechanical tests – Impact test at low temperature for insulations and sheaths
IEC 60811-508, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 508: Mechanical tests – Pressure test at high temperature for insulation and sheaths
IEC 60811-509, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 509: Mechanical tests – Test for resistance of insulations and sheaths to cracking (heat
shock test)
IEC 60811-510, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 510: Mechanical tests – Methods specific to polyethylene and polypropylene compounds
– Wrapping test after thermal ageing in air
IEC 61034 (all parts), Measurement of smoke density of cables burning under defined
conditions
IEC TR 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 TR 61156-1-2 is due to become a TS in 2023.

IEC TR 61156-1-5, Multicore and symmetrical pair/quad cables for digital communications –
Part 1-5: Correction procedures for the measurement results of return loss and input impedance
IEC 61196-1-105, Coaxial communication cables – Part 1-105: Electrical test methods – Test
for withstand voltage of cable dielectric
IEC 62012-1:2002, Multicore and symmetrical pair/quad cables for digital communications to
be used in harsh environments – Part 1: Generic specification
IEC 62153-4-3:2013, Metallic communication cables 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
IEC 62153-4-9, Metallic communication cable test methods – Part 4-9: Electromagnetic
compatibility (EMC) – Coupling attenuation of screened balanced cables, triaxial method
IEC 62255 (all parts), Multicore and symmetrical pair/quad cables for broadband digital
communications (high bit rate digital access telecommunication networks) – Outside plant
cables
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 following terms and definitions 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
3.1
resistance unbalance
difference in resistance of the conductors within a pair or one side of a quad or between pairs
or quads
Note 1 to entry: Resistance unbalance is expressed as a percentage (%).
3.2
mutual capacitance
electrical charge storage parameter of a pair of conductors (or with respect to the side of a
quad)
Note 1 to entry: Mutual capacitance is one of the four primary transmission line parameters: mutual capacitance,
mutual inductance, resistance and conductance.
Note 2 to entry: Mutual capacitance is expressed in pF/m.
3.3
capacitance unbalance to earth
arithmetic difference of the capacitance to earth of the conductors of a pair or one side of a
quad
Note 1 to entry: Capacitance unbalance is expressed in pF/m.

– 10 – IEC 61156-1:2023 © IEC 2023
3.4
screen
continuous conducting layer or assembly of conducting layers having the function of reducing
the penetration of an electric, magnetic or electromagnetic field into a given region
[SOURCE: IEC 60050-195:2021,195-02-37, modified – "continuous conducting layer or
assembly of conducting layers having the function of reducing " has replaced "device intended
to reduce "]
3.5
balun
device to provide impedance transformation between balanced and unbalanced components
[SOURCE:ISO/IEC 11801-4:2017, 3.1.2]
3.6
balunless
virtual balun used instead of the physical transformers, achieved by mathematical algorithm,
and calculated from lumped parameters or distributed parameter network
3.7
transfer impedance
Z
T
quotient of the longitudinal voltage of an electrically short uniform cable, induced in the outer
circuit – formed by the screen under test and the measuring jig – and the current fed into the
inner circuit – the cable under test itself or vice versa, related to unit length
Note 1 to entry: Transfer impedance is expressed in mΩ/m.
[SOURCE: IEC 62153-4-3:2013, 3.3, modified – "of an electrically short uniform cable" has
been added, "outer circuit" has replaced “matched outer circuit", “the cable under test itself"
has been added, “related to unit length" has replaced "(see Figure 1)".]
3.8
coupling attenuation
a
c
for a screened balanced cable, the sum of the effects of the unbalance attenuation a of the
U
symmetric pair and the screening attenuation α of the screen of the cable under test
s
Note 1 to entry: For electrically long devices, i.e. above the cut-off frequency, the coupling attenuation α is defined
C
as the logarithmic ratio of the feeding power P and the periodic maximum values of the coupled power P in the
1 r, max
outer circuit.
Note 2 to entry: Coupling attenuation is expressed in dB.
[SOURCE: IEC 62153-4-7:2021, 3.4, modified –“cable" has replaced “device", “sum of the
effects’" has replaced “sum", Note 2 has been added.]
3.9
current carrying capacity
maximum current a cable circuit (one or several conductors) can support resulting in a specified
increase of the surface temperature of the conductor beyond the ambient temperature, not
exceeding the maximum allowed operating temperature of the cable

3.10
velocity of propagation
phase velocity
speed at which a sinusoidal signal propagates on a pair in the cable
Note 1 to entry: Velocity of propagation is expressed in m/s.
3.11
phase delay
delay
time duration between the instants that the wave front of a sinusoidal travelling wave, defined
by a specified phase, passes two given points in a cable
Note 1 to entry: Phase delay is expressed in s/m.
3.12
differential phase delay
delay skew
difference in phase delay between any two pairs in the cable
Note 1 to entry: Differential phase delay (skew) is expressed in s.
3.13
attenuation
decrease in magnitude of power of a signal that propagates along a pair of a cable
Note 1 to entry: Attenuation is expressed in dB/m.
3.14
ambient temperature
temperature of the room or space surrounding the cable
Note 1 to entry: Ambient temperature is expressed in degree Celsius (°C).
3.15
operating temperature
surface temperature of the conductors of a cable
Note 1 to entry: The operating temperature is the sum of the ambient temperature and of the temperature increase
due to the carried power.
Note 2 to entry: Operating temperature is expressed in degree Celsius (°C).
3.16
unbalance attenuation
UA
logarithmic ratio of the differential mode power to the common mode power in a balanced line,
or vice versa
Note 1 to entry: Unbalance attenuation is expressed in dB.
Note 2 to entry: Unbalance attenuation is also often referred to as conversion loss: TCL (transverse conversion
loss), TCTL (transverse conversion transfer loss), LCL (longitudinal conversion loss), LCTL (longitudinal conversion
transfer loss), EL TCTL (equal level transverse conversion transfer loss) and EL LCTL (equal level longitudinal
conversion loss transfer loss).
3.17
transverse conversion loss
TCL
logarithmic ratio of the differential-mode circuit power at the near end and the common-mode
coupling power measured at the near end

– 12 – IEC 61156-1:2023 © IEC 2023
3.18
equal level transverse conversion transfer loss
EL TCTL
output-to-output measurement of the logarithmic ratio of the differential-mode circuit power at
the near end and the common-mode coupling power measured at the far end
Note 1 to entry: EL TCTL is calculated by the difference between the measured TCTL and the differential-mode
insertion loss of the disturbed pair.
3.19
near-end crosstalk
NEXT
magnitude of the signal power coupling from a disturbing pair at the near end to a disturbed
pair measured at the near end
Note 1 to entry: Near-end crosstalk is expressed in dB.
3.20
far-end crosstalk
FEXT
magnitude of the signal power coupling from a disturbing pair at the near end to a disturbed
pair measured at the far end
Note 1 to entry: Far-end crosstalk is expressed in dB.
3.21
power sum of crosstalk
PS
summation of the crosstalk power from all disturbing pairs into a disturbed pair
Note 1 to entry: The summation is applicable to near-end and far-end crosstalk.
Note 2 to entry: The power sum of crosstalk is expressed in dB.
3.22
attenuation to crosstalk ratio, far-end
ACR-F
arithmetic difference between the far-end crosstalk and the attenuation of the disturbed pair
Note 1 to entry: Attenuation to crosstalk ratio, far-end, is expressed in dB.
3.23
alien (exogenous) near-end crosstalk
ANEXT
near-end crosstalk where the disturbing and disturbed pairs are contained in different cables
Note 1 to entry: Alien (exogenous) near-end crosstalk is expressed in dB.
3.24
alien (exogenous) far-end crosstalk
AFEXT
far-end crosstalk where the disturbing and disturbed pairs are contained in different cables
Note 1 to entry: Alien (exogenous) far-end crosstalk is expressed in dB.
3.25
alien (exogenous) far-end crosstalk
AACR-F
far-end crosstalk where the disturbing and disturbed pairs are contained in different cables
Note 1 to entry: Alien (exogenous) far-end crosstalk is expressed in dB.

3.26
power sum of alien (exogenous) near-end crosstalk
PS ANEXT
summation of the near-end alien (exogenous) crosstalk power from all disturbing pairs into a
disturbed pair in different cables
Note 1 to entry: The power sum of alien (exogenous) near-end crosstalk is expressed in dB.
3.27
power sum of alien (exogenous) far-end crosstalk
PS AACR-F
summation of the alien (exogenous) far-end crosstalk power from all disturbing pairs into a
disturbed pair in different cables
Note 1 to entry: The power sum of far-end alien (exogenous) crosstalk is expressed in dB.
3.28
characteristic impedance
Z
C
impedance at the input of a homogeneous line of infinite length
Note 1 to entry: The impedance value is expressed in Ω, at relevant frequencies, as the square root of the product
of the impedance measured at the near end (input) of a cable pair when the far end is terminated by an open circuit
load and then an short circuit load.
Note 2 to entry: The asymptotic value at high frequencies is denoted as Z .
∞
Note 3 to entry: The characteristic impedance of a homogeneous cable pair is given by the quotient of a voltage
wave and current wave which are propagating in the same direction, either forwards or backwards.
Note 4 to entry: For homogeneous ideal cables, this test method yields a flat smooth curve over the whole frequency
range. Real cables with distortions give curves with some roughness.
3.29
terminated input impedance
Z
in
impedance value, expressed in Ω, at relevant frequencies, measured at the near end (input)
when the far end is terminated with the system nominal impedance, Z
R
3.30
fitted characteristic impedance
Z
m
impedance value, expressed in Ω, calculated by applying a least squares function fitting
algorithm to the measured characteristic impedance values
3.31
mean characteristic impedance
Z
∞
asymptotic value at which the characteristic impedance approaches at sufficiently high
frequencies (≈100 MHz) such that the imaginary part (phase angle) is insignificant
Note 1 to entry: Normally measured from the capacitance and time delay.
Note 2 to entry: Applicable for cables with frequency independence of mutual capacitance.
3.32
return loss
RL
ratio of reflected power to input power at the input terminals of a cable pair
Note 1 to entry: Return loss is expressed in dB.

– 14 – IEC 61156-1:2023 © IEC 2023
3.33
bundled cable
grouping or assembly of several individual cables that are systematically laid up
Note 1 to entry: Bundled cables are also referred to as speed-wrap, whip, or loomed cables.
3.34
remote powering
supply of power to application specific equipment via balanced cabling
[SOURCE: ISO/IEC TS 29125:2017, 3.1.5]
3.35
safety extra-low voltage
SELV
AC voltage the RMS value of which does not exceed 50 V or ripple-free DC voltage the value
of which does not exceed 120 V, between conductors, or between any conductor and reference
earth, in an electric circuit which has galvanic separation from the supplying electric power
system by such means as a separate-winding transformer
Note 1 to entry: Maximum voltage lower than 50 V AC or 120 V ripple-free DC may be specified in particular
requirements, especially when direct contact with live parts is allowed.
Note 2 to entry: The voltage limit should not be exceeded at any load between full load and no-load when the source
is a safety isolating transformer.
Note 3 to entry: Ripple-free qualifies conventionally an RMS ripple voltage of not more than 10 % of the DC
component; the maximum peak value does not exceed 140 V for a nominal 120 V ripple-free DC system and 70 V for
a nominal 60 V ripple-free DC system.
3.36
continuous operating temperature
COT
maximum temperature which ensures the stability and integrity of the material for the expected
life of the equipment, or part, in its intended application
3.37
hygroscopic
characteristic of a material to absorb moisture from the atmosphere
3.38
wicking
longitudinal flow of a liquid in a material due to capillary action
4 Installation considerations
The cables shall be designed to meet the installation conditions encountered for each area as
follows.
a) Equipment cables
The cables are used between work stations and peripheral equipment (for example, printer).
b) Work area cables
The cables are used between the work station and the communication outlets.
c) Horizontal floor wiring cables
The cables are used between the work area communication outlet and the communication
closet.
d) Riser cables and building back-bone cables
The cables are used for horizontal installation or vertically between floors.

e) Campus cables
These cables are used to interconnect buildings and shall be suitable for outdoor
installation. The cables shall be sheathed and protected in accordance with IEC 62255 (all
parts).
f) Delivery of power
For cables delivering power using only SELV systems for remote powering, the COT shall
be considered.
NOTE The related document is IEC 60364-7-716.
5 Materials and cable construction
5.1 General remarks
The choice of materials and cable construction shall be suitable for the intended application
and installation of the cable. Any special requirements for EMC (electromagnetic compatibility),
...