Wiring Colours

UK Electrical Wiring Colours

The electrical wiring colours in the UK are, Live wire = Brown, Neutral wire = Blue, Earth wire = Green and Yellow (Yellow with a green stripe).

UK Single Phase Electrical Wiring Colours are:

• Line (Live) = Brown
• Neutral = Blue
• Earth = Green / Yellow

UK Three Phase Electrical Wiring Colours are:

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

Note: The “Line” conductor might also be referred to as the “Live” or “Hot” conductor depending on the country.

In 2004 the UK wiring regulations changed, the old UK wiring colours before 2004 were as follows,

UK Single Phase Wiring Colours (before 2004):

• Line (Live) = Red
• Neutral = Black
• Earth = Green /Yellow

UK Three Phase Wiring Colours (before 2004):

• Line L1 or “R” (red phase) = Red
• Line L2 or “Y” (yellow phase) = Yellow
• Line L3 or “B” (blue phase) = Blue
• Neutral = Black
• Earth = Green / Yellow

As the UK wiring colours have changed, great care should be taken before undertaking extension, alteration or repair that all conductors are correctly identified.

Note: Green & Yellow = A single green & yellow stripy conductor, NOT a choice between a single green or single yellow conductor.

USA Electrical Wiring Colors

The electrical wiring colors in the United States vary depending on the voltages, they also use a “Hot” wire in some circumstances.

USA Single Phase Wiring Colors (120v, 208v, 240v):

• Line = Black
• Neutral = White
• Earth = Green

USA Three Phase Wiring Colors (120v, 208v, 240v):

• Line L1 = Black
• Line L2 = Red
• Line L3 = Blue
• Neutral = White
• Earth = Green

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