Wiring colours according to IEC
Which colour each conductor uses in an installation and in the internal wiring of control panels and machines, and how colours differ in other countries.
Phases, neutral and protective earth
These are the conductor colours of an AC installation according to IEC 60445, the same ones used throughout Europe:
| Conductor | Colour |
|---|---|
L1 Phase 1 | Brown |
L2 Phase 2 | Black |
L3 Phase 3 | Grey |
N Neutral | Light blue |
PE Protective earth | Green-and-yellow |
Green-and-yellow is reserved for the protective conductor and must not be used for anything else. Light blue is reserved for the neutral; if the circuit has no neutral, it may be used for another function, but never as a protective conductor.
Control panel and machine wiring
For the internal wiring of the electrical equipment of machines, IEC 60204-1 recommends these colours by circuit type:
| Colour | Circuit |
|---|---|
| Black | AC and DC power circuits |
| Red | AC control circuits |
| Blue | DC control circuits |
| Orange | Circuits that stay live with the main switch open, such as interlocks supplied from an external source |
| Light blue | Neutral |
| Green-and-yellow | Protective earth |
Orange warns that the wire may be live even when the panel is switched off. If your company uses other colours, state them on the cover sheet of the schematic.
Old colours and other countries
Not every installation follows the current colours. These are the cases you will meet most often:
| Where | L1 | L2 | L3 | N | PE |
|---|---|---|---|---|---|
| Europe (current) | Brown | Black | Grey | Light blue | Green-and-yellow |
| UK, before 2004 | Red | Yellow | Blue | Black | Green-and-yellow |
| USA, 208/120 V (custom) | Black | Red | Blue | White or grey | Green |
| USA, 480/277 V (custom) | Brown | Orange | Yellow | Grey | Green |
In the USA, the NEC only sets the colour of the neutral (white or grey) and of the grounding conductor (green, green with yellow stripes or bare); phase colours are a widespread custom, not a requirement.
Practical rules
- Measure before you touch. In old or modified installations the colours may not follow the standard: always verify that there is no voltage with a tester, never trust the colour alone.
- Colour and number. The colour tells you the wire's function; its number, which terminal it goes to. Both must match the schematic.
- Control cables. In multicore cables the cores are usually numbered rather than coloured: identify them by their number.
- Document the colour code. Put it on the cover sheet of the schematic, especially if you depart from IEC 60204-1.
IEC 60617 symbols guide kW to amps calculator
Common questions
What colour is the neutral?
Light blue, both in installations and in machine wiring.
Can I use green-and-yellow for anything else?
No. Green-and-yellow is reserved for the protective conductor.
Why are there red wires in a panel if the phases are brown, black and grey?
Because, in the internal wiring of machines, IEC 60204-1 recommends red for AC control circuits. It is not a phase of the installation.
What colour is used for 24 V DC wiring?
IEC 60204-1 recommends blue for DC control circuits, which is what a panel's 24 V is.
Links
- IEC 60445 · Identification of terminals and conductors, including their colours (official IEC page)
- IEC 60204-1 · Electrical equipment of machines: general requirements (official IEC page)
- Reference designation according to IEC 81346 · FaseCAD guide