ISO/IEC TS 29125:2017/AMD2:2024

Amendment 2 - Information technology - Telecommunications cabling requirements for remote powering of terminal equipment

The content of the corrigendum 1 (2025-12) has been included in this copy.

General Information

• Status: Published
• Publication Date: 24-Oct-2024
• 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
• Start Date: 25-Oct-2024
• Completion Date: 15-Nov-2024

Relations

• Amends: ISO/IEC TS 29125:2017 - Information technology - Telecommunications cabling requirements for remote powering of terminal equipment
• Effective Date: 08-Dec-2023
• Corrected By: ISO/IEC TS 29125:2017/AMD2:2024/COR1:2025 - Corrigendum 1 - Amendment 2 - Information technology - Telecommunications cabling requirements for remote powering of terminal equipment
• Effective Date: 12-Dec-2025

Overview

ISO/IEC TS 29125:2017/AMD2:2024 is an amendment to the international technical specification for telecommunications cabling requirements for remote powering of terminal equipment. This Amendment 2 extends the guidance for remote powering over single-pair (1‑pair) balanced cabling to support currents per conductor up to 2 000 mA, and incorporates the content of Corrigendum 1 (2025‑12). It updates temperature‑rise models, cable bundling guidance, and related test/connector references to help designers and installers manage thermal and electrical limits when delivering power over data cabling.

Key topics and technical requirements

• Extended current capability: explicit support and tables for 1‑pair cabling carrying up to 2 000 mA per conductor (with higher values shown for information only).
• Thermal modelling and temperature rise: revised tables and figures that relate conductor current, conductor diameter and bundle size (7, 19, 37, 61, 91 cables) to expected temperature rise in air and conduit installations.
• Conductor diameters considered: guidance based on common diameters (examples in the amendment include 0.40 mm, 0.57 mm and 1.02 mm conductor diameters) and strand/cord constructions.
• Bundle basis and scaling: 37‑cable bundles are used as the primary basis for temperature and current development; additional guidance is provided for other bundle counts and how to reduce temperature increase (e.g., by spacing, conduit selection).
• Environmental temperature limits: alignment with ISO/IEC 11801 family limits (temperature ceilings are noted for MICE environments).
• Connector and hardware considerations: notes referencing connector endurance and degradation under electrical load and pointers to the IEC connector test schedules (IEC 60512‑99‑001 / ‑002 / ‑003).
• Calculation updates: corrected formula units (use of K for temperature rise) and updated bundling coefficients and DC resistance assumptions for conduit calculations.

Practical applications and who uses it

This amendment is essential for:

• Cabling designers and infrastructure engineers planning power delivery over single‑pair cables (building automation, remote sensors, terminal devices).
• System integrators and installers who must size conductors and bundles to meet thermal limits and safe current capacity.
• OEMs and equipment specifiers evaluating remote powering capability for terminal equipment.
• Testing laboratories and certification bodies performing thermal and electrical compliance testing.

Use cases include modelling cable bundle heating, selecting conductor diameter, defining installation practices (air vs conduit), and assessing connector reliability under power.

Related standards

• ISO/IEC TS 29125:2017 (base technical specification)
• ISO/IEC 11801 series (cabling temperature/environment limits)
• IEC 60512‑99‑001, IEC 60512‑99‑002, IEC 60512‑99‑003 (connector tests under electrical load)
• IEC TR 61156‑1‑6 (relative resistance data referenced for bundling coefficients)

Keywords: ISO/IEC TS 29125:2017/AMD2:2024, remote powering, telecommunications cabling, 1‑pair cabling, current per conductor, temperature rise, cable bundling, conduit, conductor diameter.

Standards Content (Sample)

ISO/IEC TS 29125
Edition 1.0 2024-10
INTERNATIONAL
STANDARD
AMENDMENT 2
Information technology – Telecommunications cabling requirements for remote
powering of terminal equipment

ISO/IEC TS 29125:2017-04/AMD2:2024-10(en)

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ISO/IEC TS 29125
Edition 1.0 2024-10
INTERNATIONAL
STANDARD
AMENDMENT 2
Information technology – Telecommunications cabling requirements for remote

powering of terminal equipment

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 35.200 ISBN 978-2-8322-9893-0

– 2 – ISO/IEC TS 29125:2017/AMD2:2024
© ISO/IEC 2024
INFORMATION TECHNOLOGY –
TELECOMMUNICATIONS CABLING REQUIREMENTS
FOR REMOTE POWERING OF TERMINAL EQUIPMENT

AMENDMENT 2
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.
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 and ISO National bodies.
3) IEC and ISO documents have the form of recommendations for international use and are accepted by IEC and
ISO National bodies in that sense. While all reasonable efforts are made to ensure that the technical content of
IEC and ISO documents is accurate, IEC and ISO cannot be held responsible for the way in which they are used
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Amendment 2 to IEC ISO/IEC TS 29125:2017 has been prepared by subcommittee 25:
Interconnection of information technology equipment, of ISO/IEC joint technical committee 1:
Information technology.
The text of this Amendment is based on the following documents:
Draft Report on voting
JTC1-SC25/3272/DTS JTC1-SC25/3289/RVDTS

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 Amendment is English.

© ISO/IEC 2024
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1, and the ISO/IEC Directives, JTC 1 Supplement
available at www.iec.ch/members_experts/refdocs and www.iso.org/directives.

___________
INTRODUCTION to the amendment
This amendment incorporates changes necessary to extend the current for remote powering
using single pair cabling up to 2 000 mA.
Introduction
Insert the following after the first bullet of the fourth paragraph:
• guidance on wire diameter and bundling on heating;
1 Scope
Replace the second bullet of list item a), added by Amendment 1, with:
• 1-pair balanced cabling using currents per conductor of up to 2 000 mA;
In the NOTE, delete "4-pair".
6.3 Temperature rise and current capacity
Replace the last sentence of the first paragraph with the following sentence:
The standards in the ISO/IEC°11801 series specify this temperature up to 60 °C in MICE C
environments and 70 °C in MICE C and C environments.
2 3
– 4 – ISO/IEC TS 29125:2017/AMD2:2024
© ISO/IEC 2024
Replace the existing Table 5, added by Amendment 1, with the following new Table 5:
Table 5 – Maximum current per conductor versus temperature rise
in a 37 1-pair cable bundle in air and conduit
Temperature
Current per conductor
rise
0,57 mm wire diameter 0,40 mm stranded wire 1,02 mm stranded wire
diameter (cords) diameter (cords)
K mA mA mA
air conduit air conduit air conduit
5 866 738 608 518 1 550 1 320
7,5 1 061 904 744 634 1 900 1 620
10 1 225 1 044 860 732 2 190 1 870
12,5 1 370 1 167 961 819 - 2 090
15 1 501 1 278 1 053 897 - -
17,5 1 621 1 381 1 137 969 - -
20 1 733 1 476 1 216 1 036 - -
Temperature rise above 10 K shown in grey background is not recommended for cables installed in an environment
that can reach 50 °C.
NOTE 1 These values are based on conductor temperature measurement of typical cables and cords.
NOTE 2 Currents above 2 000 mA are for information only.

In Table 6, added by Amendment 1, delete column "0,32 mm diameter", as follows:
Table 6 – Calculated worst case current per conductor versus temperature rise
in a bundle of 37 1-pair cables of different conductor diameters in air and conduit
0,40 mm 0,51 mm 0,57 mm 0,65 mm 0,81 mm 1,02 mm
diameter diameter diameter diameter diameter diameter

∆T mA mA mA mA mA mA
°C air conduit air conduit air conduit air conduit air conduit air conduit
2 384 327 490 417 548 466 624 532 779 663 981 835
4 543 463 693 590 775 660 883 753 1 101 938 1 387 1 181
6 666 567 849 723 949 808 1 082 922 1 349 1 149 1 699 1 446
8 769 655 981 835 1 096 933 1 249 1 065 1 558 1 327 1 962 1 670
10 860 732 1 096 934 1 225 1 044 1 397 1 190 1 742 1 484 2 194 1 867
12 942 802 1 201 1 023 1 342 1 143 1 530 1 304 1 908 1 625 2 403 2 046
14 1 017 867 1 297 1 105 1 450 1 235 1 653 1 409 2 061 1 755 2 596 2 210
16 1 087 926 1 387 1 181 1 550 1 320 1 767 1 506 2 203 1 877 2 775 2 362
18 1 153 983 1 471 1 253 1 644 1 400 1 874 1 597 2 337 1 991 2 943 2 506
20 1 216 1 036 1 551 1 321 1 733 1 476 1 976 1 684 2 463 2 098 3 102 2 641
Temperature rise above 10 °C shown in grey background is not recommended.
The values in this table are based on the implicit DC resistance derived from the insertion loss of the various
conductor diameters of cable. Manufacturers' and/or suppliers' specifications give information relating to a
specific cable.
NOTE 1 The current per conductor for each 1-pair cable is also dependent on the cable construction.
NOTE 2 Currents above 2 000 mA are for information only.

© ISO/IEC 2024
6.4.3 Cable count within a bundle
Replace the first three paragraphs, added by Amendment 1, with the following text:
This document uses 37-cable bundles as the basis for developing the temperature rise and
current per conductor with all pairs energized. For other cases (e.g. where bundle count
exceeds 37 cables), the guidelines provided in 6.4.4 can be used.
Refer to Table 7 to determine the maximum temperature rise using 2 000 mA per conductor for
1-pair cable bundles of different count.
NOTE The temperature rise
...