UK Wiring Colour Codes - Live, Neutral and Earth Wire Colours
In the current UK system, the live wire is brown, the neutral wire is blue, and the earth wire is green and yellow. These colours apply to all fixed wiring installed since April 2006 and all flexible cables since 1971. Installations before 2006 used red for live and black for neutral.
This guide gives the current and old colours for single-phase, three-phase, and DC circuits, explains when and why the colours changed, sets out the safety rules where old and new colours mix, and shows which cable holds which colours.
At a glance: Brown = live, blue = neutral, green/yellow = earth. In three-phase, the live cores are brown (L1), black (L2), and grey (L3). Need the cable to match? We stock the full range in every standard colour - see our electrical cables range.
What are the current UK wiring colours?
Since 31 March 2006, all new fixed wiring in the UK must use the harmonised colours set out in BS 7671 (the IET Wiring Regulations). The table below gives the single-phase colours, the conductor each colour identifies, and its function in the circuit.
| Colour | Conductor | Function |
|---|---|---|
| Brown | Live (line) | Carries current from the supply to the circuit |
| Blue | Neutral | Returns current to the supply to complete the circuit |
| Green and yellow | Earth (CPC) | Provides a safe path for fault current to protect against shock |
Flexible cables use the same brown, blue, and green/yellow system. Flex changed to these colours in 1971, more than 30 years before fixed wiring. In a UK plug, brown connects to the live terminal on the right, blue to neutral on the left, and green/yellow to earth at the top.
What were the old UK wiring colours?
UK fixed wiring installed between 1977 and 2006 used red for the live conductor and black for the neutral. The earth was green and yellow from 1977, and plain green before that. The table below gives the pre-2006 single-phase colours against the current equivalent.
| Conductor | Old colour (pre-2006) | Current colour |
|---|---|---|
| Live (line) | Red | Brown |
| Neutral | Black | Blue |
| Earth (CPC) | Green/yellow (green pre-1977) | Green/yellow |
The change was published on 1 April 2004 and became mandatory for new installations on 31 March 2006. Wiring fitted in that transition window can use either system. The change aligned the UK with the IEC 60446 European harmonised standard.
What are the three-phase wiring colours?
Three-phase supplies are found in commercial and industrial premises and carry three line conductors plus neutral and earth. The current and old three-phase colours are set out below. The earth is green and yellow in both systems.
| Conductor | Current colour | Old colour (pre-2006) |
|---|---|---|
| Line 1 (L1) | Brown | Red |
| Line 2 (L2) | Black | Yellow |
| Line 3 (L3) | Grey | Blue |
| Neutral | Blue | Black |
| Earth (CPC) | Green/yellow | Green/yellow |
Why mixed old and new colours are dangerous
Two colours carry opposite meanings between the old and new systems, which is the main risk in any installation that mixes both. Black was the neutral before 2006, but black is now a live L2 conductor in three-phase wiring. Blue was the L3 phase in old three-phase wiring, but blue is now the neutral. A conductor cannot be identified by colour alone in an unknown installation.
Identification rules under BS 7671
- In three-core-and-earth cable, the brown core is the live. The black and grey cores must be sleeved brown at every termination where they carry live potential, such as in two-way switch wiring.
- The bare copper earth (CPC) in twin and earth cable must be sleeved green and yellow at every termination point.
- Where old and new colours exist in the same installation, a warning notice at the consumer unit was required by BS 7671 Regulation 514.14. That regulation was deleted by Amendment 2:2022, but fitting or keeping the notice remains recommended practice.
- Always test with an approved voltage indicator before touching any conductor in an installation of unknown age.
Which colours are inside common cables?
Cable colour codes only help once the right cable is on site. The list below maps the most common UK cable types to the core colours they hold and links to each range.
- Twin and earth (6242Y): brown live and blue neutral cores plus a bare earth, in a grey or white sheath. Used for domestic lighting, sockets, cookers, and showers. See twin and earth cable.
- Three-core-and-earth (6243Y): brown, black, and grey cores plus a bare earth. Used for two-way switching and some heating controls. Black and grey are sleeved brown where live.
- Single core 6491X: available in every harmonised colour individually - brown, blue, black, grey, and green/yellow. Used for panel wiring, conduit, and meter tails. See single core cable.
- SWA armoured cable: two, three, four, and five core versions with cores numbered or colour-coded to the harmonised standard. Used for outdoor, underground, and industrial power. See SWA cable.
- Flexible H07RN-F: brown, blue, and green/yellow on three-core, with black and grey added on four and five core. Used for trailing supply and temporary power. See H07RN-F cable.
- Control cables (SY, CY, YY): numbered cores for control and signal circuits, with green/yellow earth where fitted. See SY, CY, and YY cable.
Not sure which size to order alongside the colour? Use our cable calculator or read the cable sizing guide.
UK wiring colour FAQ
What colour is the live wire in the UK?
The live wire is brown in all UK wiring installed since April 2006 and in all flexible cables since 1971. Before 2006, the live conductor in fixed wiring was red. In three-phase systems, the live cores are brown, black, and grey.
When did UK wiring colours change?
UK fixed wiring colours changed on 1 April 2004, becoming mandatory for new installations on 31 March 2006. Red and black were replaced by brown and blue. Flexible cable colours had already changed to brown and blue in 1971.
Is black wire live or neutral?
Black depends on the era. In fixed wiring before 2006, black was the neutral. In current three-phase wiring, black is a live L2 conductor at 400V. This overlap is why an unknown installation must be tested, not assumed.
What colour are L1, L2, and L3?
In current UK three-phase wiring, L1 is brown, L2 is black, and L3 is grey, with a blue neutral and a green/yellow earth. Before 2006, the phases were red, yellow, and blue, with a black neutral.
Do old wiring colours need to be replaced?
Existing installations with old colours do not need rewiring on colour alone. Any new wiring added since April 2006 must use the harmonised colours. An EICR will identify wiring that is unsafe and due for replacement on condition.
What colour is the earth wire?
The earth wire is green and yellow striped, and has been since 1977. It did not change in 2006. The bare copper earth in twin and earth cable must be sleeved green and yellow at every termination point.
Buy cable in the correct colours
We stock the full cable range in every standard harmonised colour, cut to length or in full drums, with fast delivery from six UK branches.
- Low voltage cables - twin and earth, single core, panel wiring, flexible
- SWA armoured cable - 2 to 5 core, BS5467 and BS6724
- Medium voltage cables - 3.3kV to 33kV utility and industrial
- Full electrical cables range - every type and voltage class
Free cable cutting service. Order the exact length you need and we cut it from the drum at Wrexham, reducing waste and project cost.
Cable Advice From Our Technical Team
Not sure which cable or colour you need for your installation? Our technical team has over 55 years of combined experience supplying cable for domestic, commercial, industrial, and utility projects across the UK. We can help you specify the correct cable type, size, and colour - and get the best trade price.