Wiring Colours

The following wiring colours are used for BS7671. The changes were made as a result of international standardisation (or harmonisation) with most of Europe already using this colour coding, the new colours are sometimes referred to as ‘harmonised’.

UK Single Phase Wiring

  • Line = Brown
  • Neutral = Blue
  • Earth = Green / Yellow

UK Three Phase Wiring

  • Line L1 = Brown
  • Line L2 = Black
  • Line L3 = Grey
  • Neutral = Blue
  • Earth = Green / Yellow
Note – Earth remains Green/Yellow