Fixed Wiring Colours
The changes to the colour identification of conductors in fixed wiring colours are European Harmonised colours and were introduced as part of Amendment No 2 : 2004 to BS 7671 : 2001.
Single phase installations used the traditional colours of red and black for the phase and neutral conductors are replaced by the familiar colours of brown and blue (Regulation 514-03-01). A neutral conductor, where identified by colour, must be identified by the colour blue (Regulation 514-04-01). Protective conductors remain green and yellow (Regulation 514-04-02).
Three phase installations have traditionally used red, yellow and blue for the phase conductors and black for the neutral conductor. These are replaced by the colours of brown, black and grey for the phase conductors and blue for the neutral conductor (Regulations 514-03-01 and 514-04-01). Protective conductors remain green and yellow.
All installations starting after 31st March 2004 and before 1st April 2006 may be installed in accordance with Amendment No. 2 : 2004 or Amendment No 1 : 2002, in other words they may use the harmonised colours or the old colours but not both.
Extensions, alterations or repairs to existing wiring
An extension, alteration or repair to an existing single-phase installation should be wired in the colours of brown, blue and green and yellow. If any of these changes are made to an installation that results in both the old and new wiring being present, a warning notice must be affixed at or near the appropriate distribution board or consumer unit (Regulation 514-14-01).
An extension, alteration or repair to an existing three phase installation should be wired in teh colours of brown, black, grey, blue and green and yellow. Old and new phase conductors should be fitted with sleeves marked L1, L2 and L3 and neutral conductors should be fitted with sleeves narked N to avoid any possible confusion. As with the single phase installation, where changes result in both the old and new wiring being present, a warning notice must also be affixed at or near the appropriate distribution board or consumer unit.
Identification of Conductors
|Protective conductors||Green and yellow|
|Functional earthing conductor||Cream|
|AC Power Circuit(1)|
|Phase of single-phase circuit||L||Brown|
|Neutral of single- or three-phase circuit||N||Blue|
|Phase 1 of three-phase circuit||L1||Brown|
|Phase 2 of three-phase circuit||L2||Black|
|Phase 3 of three-phase circuit||L3||Grey|
|Two-Wire Unearthed DC Power Circuit|
|Positive of two-wire circuit||L+||Brown|
|Negative of two-wire circuit||L-||Grey|
|Two-Wire Earthed DC Power Circuit|
|Positive (of negative earthed) circuit||L+||Brown|
|Negative (of negative earthed) circuit(2)||M||Blue|
|Positive (of positive earthed) circuit(2)||M||Blue|
|Negative (of positive earthed) circuit||L-||Grey|
|Three-Wire DC Power Circuit|
|Outer positive of two-wire circuit derived from three-wire system||L+||Brown|
|Outer negative of two-wire circuit derived from three-wire system||L-||Grey|
|Positive of three-wire circuit||L+||Brown|
|Mid-wire of three-wire circuit(2)(3)||M||Blue|
|Negative of three-wire circuit||L-||Grey|
|Control Circuits, ELV and Other Applications|
|Neutral or mid-wire(4)||N or M||Blue|
(1) Power circuits include lighting circuits.
(2) M identifies either the mid wire of a three wire d.c. circuit, or the earthed conductor of a two wire earthed dc circuit.
(3) Only the middle wire of three-wire circuits may be earthed.
(4) An earthed PELV conductor is blue.