ISO/IEC TS 29125:2017

ISO/IEC TS 29125
Edition 2.0 2017-04
TECHNICAL
SPECIFICATION

colour
inside
Information technology – Telecommunications cabling requirements for remote
powering of terminal equipment

ISO/IEC TS 29125:2017-04(en)

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ISO/IEC TS 29125


Edition 2.0 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



  Warning! Make sure that you obtained this publication from an authorized distributor.

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– 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

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ISO/IEC TS 29125:2017 © ISO/IEC 2017 – 3 –
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

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– 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
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The main task of the joint technical committee is to prepare International Standards. In
exceptional circumstances, the joint technical committee may propose the publication of a
Technical Specification when
• the required support cannot be obtained for the publication of an International Standard,
despite repeated efforts, or
• when the subject is still under technical development or where, for any other reason, there
is the future but not immediate possibility of an agreement on an International Standard.
Technical Specifications are subject to review within three years of publication to decide
whether they can be transformed into International Standards.
ISO/IEC TS 29125, which is a Technical Specification, has been prepared by subcommittee
25: Interconnection of information technology equipment, of ISO/IEC joint technical
committee 1: Information technology.
This first edition cancels and replaces ISO/IEC TR 29125:2010. This edition constitutes a
technical revision.

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ISO/IEC TS 29125:2017 © ISO/IEC 2017 – 5 –
This edition includes the following significant technical changes with respect to the previous
edition:
a) extension of the current per conductor from 300 mA to 500 mA;
b) provision of additional details of installation conditions that were not described in
ISO/IEC TR 29125:2010;
c) inclusion of guidelines for cords;
d) inclusion of a model to calculate temperature rise in different bundle sizes.
This Technical Specification has been approved by vote of the member bodies, and the voting
results may be obtained from the address given on the second title page.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
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INTRODUCTION
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 or more buildings or may be within a building that contains more than one
organization. The cabling may be installed prior to the selection of remote powering
equipment or powered terminal equipment.
ISO/IEC 11801-1 specifies a structure and performance requirements for cabling subsystems
that support a wide range of applications. They provide appropriate equipment interfaces to
the cabling infrastructure in equipment rooms, telecommunications rooms and work areas.
A growing number of organizations employ equipment at locations that require the provision of
remote powering. This document was created to provide supplementary information to
ISO/IEC 11801-1 to implement remote powering over generic balanced cabling as specified in
ISO/IEC 11801-1.
This document provides additional guidance for remote powering on the use of balanced
cabling systems as specified in ISO/IEC 11801-1 and guidance on different installation
conditions that require special considerations:
• information to bring together all the considerations about remote powering in a single
document;
• guidance on mating and un-mating of connectors that convey remote power.
This document does not include requirements from national or local safety standards and
regulations.
This document was developed based on a number of contributions describing remote
powering over telecommunications cabling under different installation conditions. The relevant
safety standards and regulations, application standard, and equipment manufacturers give
guidance on factors that should be taken into account during design of the generic balanced
cabling that supports the distribution of remote powering.
This document extends the current per conductor specified in ISO/IEC TR 29125:2010 from
300 mA to 500 mA. This document covers additional details of installation conditions that are
not described in ISO/IEC TR 29125:2010. This document includes guidelines for cords.

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ISO/IEC TS 29125:2017 © ISO/IEC 2017 – 7 –
INFORMATION TECHNOLOGY –

TELECOMMUNICATIONS CABLING REQUIREMENTS
FOR REMOTE POWERING OF TERMINAL EQUIPMENT



1 Scope
This document
a) addresses the support of safety extra low voltage (SELV) and limited power source (LPS)
applications that provide remote power over balanced cabling in accordance with the
reference implementations of ISO/IEC 11801 series standards using currents per
conductor of up to 500 mA and targets the support of applications that provide remote
power over balanced cabling to terminal equipment,
b) covers the transmission and electrical parameters needed to support remote power over
balanced cabling,
c) covers various installation scenarios and how these may impact the capability of balanced
cabling to support remote powering,
d) specifies design and configuration of cabling as specified in ISO/IEC 11801-1.
NOTE SELV requirements specify a maximum voltage of 60 V DC and LPS is understood in the applications
referenced to be up to 100 W supplied within 4-pair cabling.
This document includes a mathematical model to predict the behaviour of different bundle
sizes, various cabling constructions, and installation conditions for different current
capacities.
Safety (e.g. electrical safety and protection and fire) and electromagnetic compatibility (EMC)
requirements are outside the scope of this document, and are covered by other standards and
regulations. However, information given by this document can be of assistance.
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.
ISO/IEC 11801-1, Information technology – Generic cabling for customer premises – Part 1:
General requirements
ISO/IEC 14763-2, Information technology – Implementation and operation of customer
premises cabling – Part 2: Planning and installation
ISO/IEC TR 24746, Information technology – Generic cabling for customer premises – Mid-
span DTE power insertion
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 11801-1,
ISO/IEC 14763-2 and the following apply.

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ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
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• ISO Online browsing platform: available at http://www.iso.org/obp
3.1.1
power source equipment
equipment that provides power
3.1.2
cable bundle
several cables tied together or in contact with one another in a parallel configuration for at
least 1 m, with the cross-section profile of the arrangement basically circular
3.1.3
conductor
element intended to carry electric current
[SOURCE IEC 60050-151:2001, 151-12-05, modified – The 3 Notes have been deleted.]
3.1.4
current carrying capacity
maximum current a cable circuit (one or several conductors) can support resulting in a
specified increase of temperature of the conductor beyond the ambient temperature, not
exceeding the maximum allowed operating temperature of the cable
[SOURCE: IEC 61156-1:2007/AMD1:2009, 3.24, modified – "increase of temperature" has
replaced "increase of the surface temperature".]
3.1.5
remote powering
supply of power to application specific equipment via balanced cabling
3.1.6
temperature rise
difference in temperature between the initial temperature of the conductor without power and
the final temperature of the powered conductor at steady state
3.2 Abbreviated terms
EMC electromagnetic compatibility
FD floor distributor
HVAC heating, ventilation and air conditioning
PTZ pan, tilt, zoom
WAP wireless access point
4 Conformance
For cabling to comply with this document, the following applies:
a) the design of the cabling shall comply with the relevant cabling design standard of the
ISO/IEC 11801 series;
b) the installation shall comply with ISO/IEC 14763-2 as amended by the additional
requirements of this document.

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ISO/IEC TS 29125:2017 © ISO/IEC 2017 – 9 –
5 Cabling selection and performance
Cabling for remote powering should be implemented using 4-pair balanced cabling.
This cabling will be used simultaneously to support signal transmission and remote power
feeding for the terminal equipment. This document assumes the use of balanced cabling
components specified in the reference implementation clause of the relevant design standards
of the ISO/IEC 11801 series.
The transmission parameters of balanced cables related to remote powering can be found in
Annex C.
6 Installation conditions
6.1 General
Cabling may be installed in different types of continuous and non-continuous pathway
systems as described in ISO/IEC 14763-2. The installation of a cable within the pathway
systems should take into account the specified operating temperature of the cable. Due to the
Joule effect, each energized conductor has a temperature rise. Larger cable bundles have
more heat generation and therefore the temperature rise is worse than smaller cable bundles.
The cable bundle size is limited by the current capacity in 6.3 and the induced temperature
rise that results in an operating temperature of the cable, not to exceed its temperature rating.
The following guidelines for pathway selection and installation should be considered:
a) installation design including the type of pathways selected, the pathway fill factor, whether
the pathway is sealed at both ends,
b) the pathway environment and whether the pathway goes through thermally insulated
areas, in which case the type of insulation will be a significant factor. For optimal thermal
performance, pathway design should avoid any insulated areas,
c) thermal aspects of the entire pathway (e.g. open tray, closed tray, ventilated, non-
ventilated, plastic conduit, metal conduit, fire barriers) should be taken into account.
6.2 Ambient temperature
Different segments of a link can have different ambient temperatures, which can influence the
amount of remote power that can be delivered. Therefore the ambient temperature in different
length segments of a link or channel has a direct impact on the operating temperature of the
cable used for the link or channel and can limit the capability of the cable for remote power
delivery to powered terminal equipment. The worst case installed cabling condition with
respect to the maximum ambient temperature shall be used to determine the maximum
operating temperature for a link or channel when subject to remote powering.
6.3 Temperature rise and current capacity
When remote power is applied to balanced cabling, the temperature of the cabling will rise
due to resistive heat generation (Joule effect) in the conductors. Depending on cable
construction and installed cabling conditions, the heat generated will be dissipated into the
surrounding environment until a steady state is reached with the temperature of the cable
bundle (operating temperature) higher than the ambient temperature of the surrounding
environment. The maximum temperature of any cable shall not exceed the temperature rating
of the cable. The standards in the ISO/IEC 11801 series require this temperature to be 60 °C
(minimum).

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Temperature rise in the cable will lead to an increase in insertion loss as indicated in the
reference implementations of the ISO/IEC 11801 series standards and should be taken into
account when selecting cables and using them in links or channels. The maximum length of
the channel or link should be reduced based on the maximum temperature of the cable using
the de-rating factors in ISO/IEC 11801-1.
The maximum current per con
...