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
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.