Reference
UK cable colour codes — old vs harmonised
The UK adopted the CENELEC harmonised cable colours on 31 March 2004. Any installation added to or altered from that date must use the new colours. Older installations remain legal, but where old and new colours coexist, a warning label is required by BS 7671 Regulation 514.14.
Fixed wiring (singles, T&E, SWA cores)
| Conductor | Pre-2004 | Harmonised (current) |
|---|---|---|
| Line 1 / Phase | Red | Brown |
| Line 2 | Yellow | Black |
| Line 3 | Blue | Grey |
| Neutral | Black | Blue |
| Protective (CPC / earth) | Green/Yellow | Green/Yellow |
Flexible cords (appliance flex)
Line
Pre-1970: Red
Modern: Brown
Neutral
Pre-1970: Black
Modern: Blue
Earth
Pre-1970: Green
Modern: Green/Yellow
Mixed-colour warning label
BS 7671 Regulation 514.14: where a distribution board or consumer unit contains cables of both the old and new colour codes, a warning notice must be affixed reading:
CAUTION
This installation has wiring colours to two versions of BS 7671. Great care should be taken before undertaking extension, alteration or repair that all conductors are correctly identified.