Recommendation ITU-T L.1203 defines the requirements and guidelines for DC power distribution identification by colour and marking in Telecom/ICT installations (wire, 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 ITU-T 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.

Work item jointly developed with ETSI TC EE to become a technically aligned deliverable.