ISO/IEC TS 29125:2017

Information technology - Telecommunications cabling requirements for remote powering of terminal equipment

ISO/IEC TS 29125:2017(E) This document specifies the use of generic balanced cabling for customer premises, as specified in the ISO/IEC 11801 series, for remote powering of terminal equipment. It provides guidance on new cabling installations and renovations. The customer premises may encompass one of more buildings or may be within a building that contains more than one organization. The cabling may be installed prior to the seelction of remote powering equipment or powered terminal equipment.

General Information

• Status: Published
• Publication Date: 24-Oct-2024
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 35.200 - Interface and interconnection equipment
• Technical Committee: ISO/IEC JTC 1/SC 25 - Interconnection of information technology equipment
• Drafting Committee: WG 3 - ISO/IEC JTC 1/SC 25/WG 3
• Current Stage: PPUB - Publication issued
• Completion Date: 27-Mar-2019

Relations

• Amended By: ISO/IEC TS 29125:2017/AMD2:2024 - Amendment 2 - Information technology - Telecommunications cabling requirements for remote powering of terminal equipment
• Effective Date: 08-Dec-2023
• Amended By: ISO/IEC TS 29125:2017/AMD1:2020 - Amendment 1 - Information technology - Telecommunications cabling requirements for remote powering of terminal equipment
• Effective Date: 05-Sep-2023

Standards Content (Sample)

ISO/IEC TS 29125
Edition 1.0 2017-04
TECHNICAL
SPECIFICATION
colour
inside
Information technology – Telecommunications cabling requirements for remote
powering of terminal equipment

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about
ISO/IEC copyright or have an enquiry about obtaining additional rights to this publication, please contact the address
below or your local IEC member National Committee for further information.

IEC Central Office Tel.: [phone]
3, rue de Varembé Fax: [phone]
CH-1211 Geneva 20 [e-mail]
Switzerland www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the

latest edition, a corrigenda or an amendment might have been published.

IEC Catalogue - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
The stand-alone application for consulting the entire The world's leading online dictionary of electronic and
bibliographical information on IEC International Standards, electrical terms containing 20 000 terms and definitions in
Technical Specifications, Technical Reports and other English and French, with equivalent terms in 16 additional
documents. Available for PC, Mac OS, Android Tablets and languages. Also known as the International Electrotechnical
iPad. Vocabulary (IEV) online.

IEC publications search - www.iec.ch/searchpub IEC Glossary - std.iec.ch/glossary
The advanced search enables to find IEC publications by a 65 000 electrotechnical terminology entries in English and
variety of criteria (reference number, text, technical French extracted from the Terms and Definitions clause of
committee,…). It also gives information on projects, replaced IEC publications issued since 2002. Some entries have been
and withdrawn publications. collected from earlier publications of IEC TC 37, 77, 86 and

CISPR.
IEC Just Published - webstore.iec.ch/justpublished

Stay up to date on all new IEC publications. Just Published IEC Customer Service Centre - webstore.iec.ch/csc
details all new publications released. Available online and If you wish to give us your feedback on this publication or
also once a month by email. need further assistance, please contact the Customer Service
Centre: [e-mail].
ISO/IEC TS 29125
Edition 1.0 2017-04
TECHNICAL
SPECIFICATION
colour
inside
Information technology – Telecommunications cabling requirements for remote

powering of terminal equipment

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 35.200 ISBN 978-2-8322-4223-0

– 2 –  ISO/IEC TS 29125:2017 © ISO/IEC 2017
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms, definitions and abbreviated terms . 7
3.1 Terms and definitions . 7
3.2 Abbreviated terms . 8
4 Conformance . 8
5 Cabling selection and performance . 9
6 Installation conditions . 9
6.1 General . 9
6.2 Ambient temperature. 9
6.3 Temperature rise and current capacity . 9
6.4 Factors affecting temperature increase . 11
6.4.1 General . 11
6.4.2 Installation near equipment . 11
6.4.3 Cable count within a bundle . 11
6.4.4 Reducing temperature increase . 12
6.4.5 Cable bundle suspended in air . 13
6.4.6 Administration. 14
7 Remote power delivery over balanced cabling . 14
8 Connecting hardware . 15
Annex A (informative) Mitigation considerations for installed cabling . 17
A.1 General . 17
A.2 Minimum cabling class . 17
A.3 Bundle size and location . 17
A.4 Mitigation options . 17
Annex B (informative) Modelling temperature rise for cable types, bundle sizes and
installation conditions . 18
B.1 Model basics . 18
B.2 Power dissipated (P) . 18
B.3 Temperature difference from ambient temperature to bundle surface (∆T ) . 19
u
B.3.1 Model equations . 19
B.3.2 Typical values for constant ρ . 19
u
B.4 Temperature difference from bundle surface to bundle centre (∆T ) . 19
th
B.4.1 Model equations . 19
B.4.2 Typical values for constant ρ . 19
th
B.5 Temperature variation within the bundle (∆T(x)) . 20
B.6 Alternative presentation of the model . 20
B.7 Adaptation model used to derive temperature rise vs. cables in a bundle . 20
B.8 Calculations . 21
B.9 Example. 21
B.10 Coefficients for air and conduit. 22
Annex C (informative) Transmission parameters related to remote powering. 23
C.1 DC loop resistance. 23

C.2 DC resistance unbalance (within pair) . 23
C.3 DC resistance unbalance (pair to pair) . 24
Annex D (informative) Illustrations of heating of various bundle sizes and
configurations . 26
D.1 Limiting cable bundle size . 26
D.2 Separating into smaller bundles . 27
Annex E (informative) Test protocol . 28
E.1 Background. 28
E.2 Test set-up . 28
Annex F (informative) Detailed test procedure . 30
F.1 General . 30
F.2 Test set-up . 30
F.2.1 Thermocouple placement . 30
F.2.2 Measurement of cable bundle in air . 31
F.2.3 Measurement of cable bundle in conduit . 32
Bibliography . 34

Figure 1 – Examples of end point powering systems using signal pairs (top) and spare
pairs (bottom) . 14
Figure 2 – Examples of mid-span powering systems . 15
Figure B.1 – Temperature rise profile . 18
Figure D.1 – 91-cable bundle . 26
Figure D.2 – Three bundles of 37 cables . 26
Figure D.3 – Three bundles of 37 cables with separation . 27
Figure E.1 – 37-cable bundle and temperature location. 28
Figure E.2 – "Perfect bundle" and thermocouple configuration . 29
Figure E.3 – Conductor configuration . 29
Figure F.1 – Placement of thermocouple . 30
Figure F.2 – Securing of the thermocouple. 31
Figure F.3 – Test set-up for cable bundles in air . 32
Figure F.4 – Test set-up for cable bundles in conduit . 33

Table 1 – Maximum current per conductor versus temperature rise in a 37-cable
bundle in air and conduit (all 4 pairs energized) . 10
Table 2 – Calculated worst case current per conductor versus temperature rise in a
bundle of 37 4-pair cables (all pairs energized) . 11
Table 3 – Temperature rise versus cable bundle size (500 mA per conductor) . 12
Table 4 – Temperature rise for a type of cable versus the number of energized pairs in
a 37-cable bundle (500 mA per conductor) . 13
Table B.1 – Bundling coefficients for different types of cables and cords (all 4 pairs
energized) . 22
Table C.1 – Maximum DC loop resistance of channels . 23
Table C.2 – DC resistance unbalance of cables, connecting hardware and channels . 24
Table C.3 – DC resistance unbalance (pair to pair) . 25

– 4 –  ISO/IEC TS 29125:2017 © ISO/IEC 2017
INFORMATION TECHNOLOGY –
TELECOMMUNICATIONS CABLING REQUIREMENTS
FOR REMOTE POWERING OF TERMINAL EQUIPMENT

FOREWORD
1) ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are members of
ISO or IEC participate in the development of International Standards through technical committees established
by the respective organization to deal with particular fields of technical activity. ISO and IEC technical
committees collaborate in fields of mutual interest. Other international organizations, governmental and non-
governmental, in liaison with ISO and IEC, also take part in the work. In the field of information technology,
ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
2) The formal decisions or agr
...

ISO/IEC TS 29125
Edition 1.0 2017-04
TECHNICAL
SPECIFICATION
colour
inside
Information technology – Telecommunications cabling requirements for remote
powering of terminal equipement

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about
ISO/IEC copyright or have an enquiry about obtaining additional rights to this publication, please contact the address
below or your local IEC member National Committee for further information.

IEC Secretariat Tel.: [phone]
3, rue de Varembé [e-mail]
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

IEC publications search - webstore.iec.ch/advsearchform IEC Products & Services Portal - products.iec.ch
The advanced search enables to find IEC publications by a Discover our powerful search engine and read freely all the
variety of criteria (reference number, text, technical publications previews. With a subscription you will always
committee, …). It also gives information on projects, replaced have access to up to date content tailored to your needs.
and withdrawn publications.
Electropedia - www.electropedia.org
IEC Just Published - webstore.iec.ch/justpublished
The world's leading online dictionary on electrotechnology,
Stay up to date on all new IEC publications. Just Published
containing more than 22 300 terminological entries in English
details all new publications released. Available online and
and French, with equivalent terms in 19 additional languages.
once a month by email.
Also known as the International Electrotechnical Vocabulary

(IEV) online.
IEC Customer Service Centre - webstore.iec.ch/csc

If you wish to give us your feedback on this publication or
need further assistance, please contact the Customer Service
Centre: [e-mail].
ISO/IEC TS 29125
Edition 1.0 2017-04
TECHNICAL
SPECIFICATION
colour
inside
Information technology – Telecommunications cabling requirements for remote

powering of terminal equipement

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 35.200 ISBN 978-2-8322-4223-0

– 2 –  ISO/IEC TS 29125:2017 © ISO/IEC 2017
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms, definitions and abbreviated terms . 7
3.1 Terms and definitions . 7
3.2 Abbreviated terms . 8
4 Conformance . 8
5 Cabling selection and performance . 9
6 Installation conditions . 9
6.1 General . 9
6.2 Ambient temperature. 9
6.3 Temperature rise and current capacity . 9
6.4 Factors affecting temperature increase . 11
6.4.1 General . 11
6.4.2 Installation near equipment . 11
6.4.3 Cable count within a bundle . 11
6.4.4 Reducing temperature increase . 12
6.4.5 Cable bundle suspended in air . 13
6.4.6 Administration. 14
7 Remote power delivery over balanced cabling . 14
8 Connecting hardware . 15
Annex A (informative) Mitigation considerations for installed cabling . 17
A.1 General . 17
A.2 Minimum cabling class . 17
A.3 Bundle size and location . 17
A.4 Mitigation options . 17
Annex B (informative) Modelling temperature rise for cable types, bundle sizes and
installation conditions . 18
B.1 Model basics . 18
B.2 Power dissipated (P) . 18
B.3 Temperature difference from ambient temperature to bundle surface (∆T ) . 19
u
B.3.1 Model equations . 19
B.3.2 Typical values for constant ρ . 19
u
B.4 Temperature difference from bundle surface to bundle centre (∆T ) . 19
th
B.4.1 Model equations . 19
B.4.2 Typical values for constant ρ . 19
th
B.5 Temperature variation within the bundle (∆T(x)) . 20
B.6 Alternative presentation of the model . 20
B.7 Adaptation model used to derive temperature rise vs. cables in a bundle . 20
B.8 Calculations . 21
B.9 Example. 21
B.10 Coefficients for air and conduit. 22
Annex C (informative) Transmission parameters related to remote powering. 23
C.1 DC loop resistance. 23

C.2 DC resistance unbalance (within pair) . 23
C.3 DC resistance unbalance (pair to pair) . 24
Annex D (informative) Illustrations of heating of various bundle sizes and
configurations . 26
D.1 Limiting cable bundle size . 26
D.2 Separating into smaller bundles . 27
Annex E (informative) Test protocol . 28
E.1 Background. 28
E.2 Test set-up . 28
Annex F (informative) Detailed test procedure . 30
F.1 General . 30
F.2 Test set-up . 30
F.2.1 Thermocouple placement . 30
F.2.2 Measurement of cable bundle in air . 31
F.2.3 Measurement of cable bundle in conduit . 32
Bibliography . 34

Figure 1 – Examples of end point powering systems using signal pairs (top) and spare
pairs (bottom) . 14
Figure 2 – Examples of mid-span powering systems . 15
Figure B.1 – Temperature rise profile . 18
Figure D.1 – 91-cable bundle . 26
Figure D.2 – Three bundles of 37 cables . 26
Figure D.3 – Three bundles of 37 cables with separation . 27
Figure E.1 – 37-cable bundle and temperature location. 28
Figure E.2 – "Perfect bundle" and thermocouple configuration . 29
Figure E.3 – Conductor configuration . 29
Figure F.1 – Placement of thermocouple . 30
Figure F.2 – Securing of the thermocouple. 31
Figure F.3 – Test set-up for cable bundles in air . 32
Figure F.4 – Test set-up for cable bundles in conduit . 33

Table 1 – Maximum current per conductor versus temperature rise in a 37-cable
bundle in air and conduit (all 4 pairs energized) . 10
Table 2 – Calculated worst case current per conductor versus temperature rise in a
bundle of 37 4-pair cables (all pairs energized) . 11
Table 3 – Temperature rise versus cable bundle size (500 mA per conductor) . 12
Table 4 – Temperature rise for a type of cable versus the number of energized pairs in
a 37-cable bundle (500 mA per conductor) . 13
Table B.1 – Bundling coefficients for different types of cables and cords (all 4 pairs
energized) . 22
Table C.1 – Maximum DC loop resistance of channels . 23
Table C.2 – DC resistance unbalance of cables, connecting hardware and channels . 24
Table C.3 – DC resistance unbalance (pair to pair) . 25

– 4 –  ISO/IEC TS 29125:2017 © ISO/IEC 2017
INFORMATION TECHNOLOGY –
TELECOMMUNICATIONS CABLING REQUIREMENTS
FOR REMOTE POWERING OF TERMINAL EQUIPMENT

FOREWORD
1) ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are members of
ISO or IEC participate in the development of International Standards through technical committees established
by the respective organization to deal with particular fields of technical activity. ISO and IEC technical
committees collaborate in fields of mutual interest. Other international organizations, governmental and non-
governmental, in liaison with ISO and IEC, also take part in the work. In the field of information technology,
ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
2) The formal decisions or agreements of IEC and ISO on technical matters express, as nearly as possible, an
international consensus of opinion on the relevant subjects since each technical committee has representation
from all interested IEC National Committees and ISO member bodies.
3) IEC, ISO and ISO/IEC publications have the form of recommendations for internat
...

ISO/IEC TS 29125
Edition 1.2 2024-10
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
colour
inside
Information technology – Telecommunications cabling requirements for remote
powering of terminal equipment

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or
by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either
IEC or IEC's member National Committee in the country of the requester. If you have any questions about ISO/IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

IEC Secretariat Tel.: [phone]
3, rue de Varembé [e-mail]
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

IEC publications search - webstore.iec.ch/advsearchform IEC Products & Services Portal - products.iec.ch
The advanced search enables to find IEC publications by a Discover our powerful search engine and read freely all the
variety of criteria (reference number, text, technical publications previews, graphical symbols and the glossary.
committee, …). It also gives information on projects, replaced With a subscription you will always have access to up to date
and withdrawn publications. content tailored to your needs.

IEC Just Published - webstore.iec.ch/justpublished
Electropedia - www.electropedia.org
Stay up to date on all new IEC publications. Just Published
The world's leading online dictionary on electrotechnology,
details all new publications released. Available online and once
containing more than 22 500 terminological entries in English
a month by email.
and French, with equivalent terms in 25 additional languages.

Also known as the International Electrotechnical Vocabulary
IEC Customer Service Centre - webstore.iec.ch/csc
(IEV) online.
If you wish to give us your feedback on this publication or need

further assistance, please contact the Customer Service
Centre: [e-mail].
ISO/IEC TS 29125
Edition 1.2 2024-10
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
colour
inside
Information technology – Telecommunications cabling requirements for remote
powering of terminal equipment
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 35.200 ISBN 978-2-8322-9971-5
REDLINE VERSION – 2 – ISO/IEC TS 29125:2017+AMD1:2020
+AMD2:2024 CSV © ISO/IEC 2024
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
INTRODUCTION to Amendment 1 . 7
INTRODUCTION to Amendment 2 . 7
1 Scope . 8
2 Normative references . 8
3 Terms, definitions and abbreviated terms . 9
3.1 Terms and definitions . 9
3.2 Abbreviated terms . 9
4 Conformance . 10
5 Cabling selection and performance . 10
6 Installation conditions . 10
6.1 General . 10
6.2 Ambient temperature. 10
6.3 Temperature rise and current capacity . 11
6.4 Factors affecting temperature increase . 13
6.4.1 General . 13
6.4.2 Installation near equipment . 13
6.4.3 Cable count within a bundle . 13
6.4.4 Reducing temperature increase . 15
6.4.5 Cable bundle suspended in air . 21
6.4.6 Administration. 21
7 Remote power delivery over balanced cabling . 21
7.1 4-pair balanced cabling . 21
7.2 1-pair balanced cabling . 23
8 Connecting hardware . 24
8.1 General . 24
8.2 4-pair balanced cabling . 24
8.3 1-pair balanced cabling . 25
Annex A (informative) Mitigation considerations for installed cabling . 26
A.1 General . 26
A.2 Minimum cabling class . 26
A.3 Bundle size and location . 26
A.4 Mitigation options . 26
Annex B (informative) Modelling temperature rise for cable types, bundle sizes and
installation conditions . 27
B.1 Model basics . 27
B.2 Power dissipated (P) . 27
B.3 Temperature difference from ambient temperature to bundle surface (∆T ) . 28
u
B.3.1 Model equations . 28
B.3.2 Typical values for constant ρ . 28
u
B.4 Temperature difference from bundle surface to bundle centre (∆T ) . 28
th
B.4.1 Model equations . 28
B.4.2 Typical values for constant ρ . 28
th
B.5 Temperature variation within the bundle (∆T(x)) . 29

+AMD2:2024 CSV © ISO/IEC 2024
B.6 Alternative presentation of the model . 29
B.7 Adaptation model used to derive temperature rise vs. cables in a bundle . 29
B.8 Calculations . 30
B.9 Example. 30
B.10 Coefficients for air and conduit. 31
Annex C (informative) Transmission parameters related to remote powering. 33
C.1 DC loop resistance. 33
C.1.1 4-pair cabling . 33
C.1.2 1-pair cabling . 33
C.2 DC resistance unbalance (within pair) . 34
C.2.1 General . 34
C.2.2 4-pair cabling . 34
C.2.3 1-pair cabling . 34
C.3 DC resistance unbalance (pair to pair) . 34
Annex D (informative) Illustrations of heating of various bundle sizes and
configurations . 36
D.1 Limiting cable bundle size . 36
D.2 Separating into smaller bundles . 37
Annex E (informative) Test protocol . 38
E.1 Background. 38
E.2 Test set-up . 38
Annex F (informative) Detailed test procedure . 41
F.1 General . 41
F.2 Test set-up . 41
F.2.1 Thermocouple placement . 41
F.2.2 Measurement of cable bundle in air . 42
F.2.3 Measurement of cable bundle in conduit . 43
Bibliography . 45

Figure 3 – Temperature rise for a 0,57 mm conductor diameter 1-pair cable versus
current for different bundle sizes in air . 18
Figure 4 – Temperature rise for a 0,57 mm conductor diameter 1-pair cable versus
current for different bundle sizes in conduit . 19
Figure 6 – Temperature rise for a 1,02 mm conductor diameter 1-pair cable versus
current for different bundle sizes in air . 20
Figure 7 – Temperature rise for a 1,02 mm conductor diameter 1-pair cable versus
current for different bundle sizes in conduit . 21
Figure 1 – Examples of end point powering systems using signal pairs (top) and spare
pairs (bottom) . 22
Figure 2 – Examples of mid-span powering systems . 23
Figure 5 – Single pair remote powering using signal pairs . 24
Figure B.1 – Temperature rise profile . 27
Figure D.1 – 91-cable bundle . 36
Figure D.2 – Three bundles of 37 cables . 36
Figure D.3 – Three bundles of 37 cables with separation . 37
Figure E.1 – 37-cable bundle and temperature location. 38
Figure E.2 – "Perfect bundle" and thermocouple configuration . 39

REDLINE VERSION – 4 – ISO/IEC TS 29125:2017+AMD1:2020
+AMD2:2024 CSV © ISO/IEC 2024
Figure E.3 – 4-pair cabling conductor configuration . 39
Figure E.4 – 1-pair cabling conductor configuration . 39
Figure F.1 – Placement of thermocouple . 41
Figure F.2 – Securing of the thermocouple. 42
Figure F.3 – Test set-up for cable bundles in air .
...

ISO/IEC TS 29125
Edition 1.1 2020-05
CONSOLIDATED VERSION
TECHNICAL
SPECIFICATION
colour
inside
Information technology – Telecommunications cabling requirements for remote
powering of terminal equipment

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about
ISO/IEC copyright or have an enquiry about obtaining additional rights to this publication, please contact the address
below or your local IEC member National Committee for further information.

IEC Central Office Tel.: [phone]
3, rue de Varembé [e-mail]
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

IEC publications search - webstore.iec.ch/advsearchform Electropedia - www.electropedia.org
The advanced search enables to find IEC publications by a The world's leading online dictionary on electrotechnology,
variety of criteria (reference number, text, technical containing more than 22 000 terminological entries in English
committee,…). It also gives information on projects, replaced and French, with equivalent terms in 16 additional languages.
and withdrawn publications. Also known as the International Electrotechnical Vocabulary

(IEV) online.
IEC Just Published - webstore.iec.ch/justpublished

Stay up to date on all new IEC publications. Just Published IEC Glossary - std.iec.ch/glossary
details all new publications released. Available online and 67 000 electrotechnical terminology entries in English and
once a month by email. French extracted from the Terms and definitions clause of
IEC publications issued between 2002 and 2015. Some
IEC Customer Service Centre - webstore.iec.ch/csc entries have been collected from earlier publications of IEC
If you wish to give us your feedback on this publication or TC 37, 77, 86 and CISPR.

need further assistance, please contact the Customer Service

Centre: [e-mail].
ISO/IEC TS 29125
Edition 1.1 2020-05
CONSOLIDATED VERSION
TECHNICAL
SPECIFICATION
colour
inside
Information technology – Telecommunications cabling requirements for remote

powering of terminal equipment

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 35.200 ISBN 978-2-8322-8389-9

ISO/IEC TS 29125
Edition 1.1 2020-05
CONSOLIDATED VERSION
REDLINE VERSION
colour
inside
Information technology – Telecommunications cabling requirements for remote
powering of terminal equipment

– 2 – ISO/IEC TS 29125:2017+AMD1:2020 CSV
© ISO/IEC 2020
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
INTRODUCTION to the amendment . 7
1 Scope . 8
2 Normative references . 8
3 Terms, definitions and abbreviated terms . 9
3.1 Terms and definitions . 9
3.2 Abbreviated terms . 9
4 Conformance . 10
5 Cabling selection and performance . 10
6 Installation conditions . 10
6.1 General . 10
6.2 Ambient temperature. 10
6.3 Temperature rise and current capacity . 11
6.4 Factors affecting temperature increase . 13
6.4.1 General . 13
6.4.2 Installation near equipment . 13
6.4.3 Cable count within a bundle . 13
6.4.4 Reducing temperature increase . 15
6.4.5 Cable bundle suspended in air . 19
6.4.6 Administration. 19
7 Remote power delivery over balanced cabling . 19
7.1 4-pair balanced cabling . 19
7.2 1-pair balanced cabling . 21
8 Connecting hardware . 22
8.1 General . 22
8.2 4-pair balanced cabling . 22
8.3 1-pair balanced cabling . 23
Annex A (informative) Mitigation considerations for installed cabling . 24
A.1 General . 24
A.2 Minimum cabling class . 24
A.3 Bundle size and location . 24
A.4 Mitigation options . 24
Annex B (informative) Modelling temperature rise for cable types, bundle sizes and
installation conditions . 25
B.1 Model basics . 25
B.2 Power dissipated (P) . 25
B.3 Temperature difference from ambient temperature to bundle surface (∆T ) . 26
u
B.3.1 Model equations . 26
B.3.2 Typical values for constant ρ . 26
u
B.4 Temperature difference from bundle surface to bundle centre (∆T ) . 26
th
B.4.1 Model equations . 26
B.4.2 Typical values for constant ρ . 26
th
B.5 Temperature variation within the bundle (∆T(x)) . 27
B.6 Alternative presentation of the model . 27

© ISO/IEC 2020
B.7 Adaptation model used to derive temperature rise vs. cables in a bundle . 27
B.8 Calculations . 28
B.9 Example. 28
B.10 Coefficients for air and conduit. 29
Annex C (informative) Transmission parameters related to remote powering. 30
C.1 DC loop resistance. 30
C.1.1 4-pair cabling . 30
C.1.2 1-pair cabling . 30
C.2 DC resistance unbalance (within pair) . 30
C.2.1 General . 30
C.2.2 4-pair cabling . 31
C.2.3 1-pair cabling . 31
C.3 DC resistance unbalance (pair to pair) . 31
Annex D (informative) Illustrations of heating of various bundle sizes and
configurations . 33
D.1 Limiting cable bundle size . 33
D.2 Separating into smaller bundles . 34
Annex E (informative) Test protocol . 35
E.1 Background. 35
E.2 Test set-up . 35
Annex F (informative) Detailed test procedure . 38
F.1 General . 38
F.2 Test set-up . 38
F.2.1 Thermocouple placement . 38
F.2.2 Measurement of cable bundle in air . 39
F.2.3 Measurement of cable bundle in conduit . 40
Bibliography . 42

Figure 1 – Examples of end point powering systems using signal pairs (top) and spare
pairs (bottom) . 20
Figure 2 – Examples of mid-span powering systems . 21
Figure 3 – Temperature rise for a 0,57 mm conductor diameter 1-pair cable versus
current for different bundle sizes in air . 18
Figure 4 – Temperature rise for a 0,57 mm conductor diameter 1-pair cable versus
current for different bundle sizes in conduit . 19
Figure 5 – Single pair remote powering using signal pairs . 22
Figure B.1 – Temperature rise profile . 25
Figure D.1 – 91-cable bundle . 33
Figure D.2 – Three bundles of 37 cables . 33
Figure D.3 – Three bundles of 37 cables with separation . 34
Figure E.1 – 37-cable bundle and temperature location. 35
Figure E.2 – "Perfect bundle" and thermocouple configuration . 36
Figure E.3 –4-pair cabling conductor configuration. 36
Figure E.4 – 1-pair cabling conductor configuration . 36
Figure F.1 – Placement of thermocouple . 38
Figure F.2 – Securing of the thermocouple. 39
Figure F.3 – Test set-up for cable bundles in air . 40

– 4 – ISO/IEC TS 29125:2017+AMD1:2020 CSV
© ISO/IEC 2020
Figure F.4 – Test set-up for cable bundles in conduit . 41

Table 1 – M
...