This is a safety topic, not a DIY invitation. If you are looking at old, mixed, damaged or unlabelled wiring, stop and get a competent electrician to identify and test the circuit.
UK wiring colours table
| Conductor | Current common colour | Older common colour | Safety note |
|---|---|---|---|
| Live | Brown | Red | Can be dangerous even when a switch appears off. Must be isolated and tested. |
| Neutral | Blue | Black | Neutral is not a safe-to-touch label. Faults and borrowed neutrals can be hazardous. |
| Protective earth | Green/yellow | Green/yellow, green, or bare conductor with sleeving in some older cables | Earth continuity is a safety function and should be tested, not assumed. |
| Three phase | Brown, black, grey phases with blue neutral | Red, yellow, blue phases with black neutral | Do not assume black or blue means neutral unless the whole installation is identified. |
Wire colour checker
Select what you can see. The result is only a likely identification note, not permission to work on the circuit.
Old and new colours in the same property
It is common to find old and new colours in the same house, especially where a circuit has been extended. A new brown-and-blue cable may join older red-and-black wiring inside a light fitting, junction box or consumer unit area. The important thing is not the colour memory test; it is whether the circuit has been identified, labelled and tested properly.
When to call an electrician
- You see old and new colours together and are not sure what each conductor does.
- A black, blue or grey conductor appears to be used as a live conductor.
- Earth sleeving is missing, damaged or inconsistent.
- The cable is rubber, fabric, brittle, heat damaged or shows signs of past overheating.
- You are changing bathroom, kitchen or outdoor electrical work where extra rules can apply.
Brown is not always safe to touch
Brown commonly means live, but no wire should be touched until the circuit is isolated and tested.
Blue is not a guarantee
Blue normally means neutral in modern wiring, but wiring faults and mixed circuits can make assumptions dangerous.
Black can mean different things
Black can be old neutral or a modern three-phase conductor depending on the installation.
Earth must be tested
Green/yellow sleeving suggests protective earth, but continuity and bonding still need proper testing.
If wiring colours are unclear during a kitchen, bathroom or repair job, ABC Home can arrange safe checks through its electrical service in Aberdeen.
Sources and checks used
- Electrical Safety First: guidance on common UK wire colours, including brown live, blue neutral and green/yellow earth.
- Screwfix UK wiring colours guide: practical old-vs-new colour comparison for common domestic wiring.
FAQ
What are the current UK wire colours?
For common single-phase domestic wiring, brown is live, blue is neutral and green/yellow is protective earth.
What were the old UK wiring colours?
Older single-phase wiring commonly used red for live and black for neutral, with earth often green/yellow, green or bare with sleeving depending on age and cable type.
Can old and new wire colours be mixed?
Yes. Extensions and repairs can leave old and new colours in the same installation. That is why identification and testing matter.
Is black wire neutral in the UK?
In older single-phase wiring, black was commonly neutral. In modern three-phase systems, black can be a phase conductor. Do not guess from colour alone.
