SRPS CLC ISO/IEC/TS 29125:2026

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

Scope

This document
a) addresses the support of safety extra low voltage (SELV) and limited power source (LPS) applications that provide remote power over:
• 4-pair balanced cabling in accordance with the reference implementations of EN 50173 series using currents per conductor of up to 500 mA;
• 1-pair balanced cabling using currents per conductor of up to 2 000 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 EN 50173-1.
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 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.