Summary - L.1203 (07/2026) - Colour and marking identification of up to 400 VDC power distribution for information and communication technology systems

Recommendation ITU-T L.1203 defines the requirements and guidelines for DC power distribution identification by colour and marking in telecom/information and communication technology (ICT) installations (wires, cables, electric distribution boards, interconnections, etc.). It avoids confusion and errors between the different AC and DC power interfaces and distributions used in buildings and inside telecom/ICT systems, as 400 VDC power feeding interfaces standardized in Recommendation ITUT L.1200 is used more, increasing power density of ICT equipment, energy efficiency, simplified reliable power feeding architecture, costs optimisation, etc. Recommendation ITU-T L.1203 supports the progressive introduction of up to 400 VDC installations in cohabitation with the existing -48 VDC and AC distribution.