Wiring Colours

UK Electrical Wiring Colours

There are 3 main colours for the UK 230V AC electrical colour codes, these colours include brown, blue and green / yellow, each wiring colour code has a difference purpose as set out below.

UK Single Phase (230V) Electrical Wiring Colour Codes are:

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

The new (since 2004-2006) UK wiring colours are green and yellow for the earth wire, brown for the live wire and blue for the neutral wire.

UK Three Phase (400V) Electrical Wiring Colour Codes 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 colours were changed, the new colours became mandatory in 2006, the old UK wiring colours before 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

For other great electrical articles & blogs you might like to take a look at this Top 25 Electrician Blogs and Websites, we are also listed there.