Three phase electrical cabling colour coding standards differ across the world. The image below details the standard labelling of live & neutral cabling in the UK & USA.
UK & USA standard electrical 3 phase wiring colours
| UK Old* | UK New* | USA | |
| Phase 1 | Red | Brown | Black |
| Phase 2 | Yellow | Black | Red |
| Phase 3 | Blue | Grey | Blue |
| Neutral | Black | Blue | White or Grey |
*From 31 March 2006 all cabling installed in the UK was required to comply with the harmonised cable core colours and must not use the old colours. This brings the UK more closely in line with three phase wiring practice in mainland Europe.
Some sites may therefore contain a mix of both colour standards where older & new installations exist.
Profile Portable Energy Recorder coils, LCD & software will usually refer to the UK standard colours.
The PM3000 Portable Power Quality Analyser coils are usually labelled with USA colour coding.
For more information the harmonisation of cable colours for three phase electrical installations, please con sult the IET Wiring Regulations;
https://electrical.theiet.org/