Electrical wire colours

As we already know, there are two main types of alternating current electrical installations: single-circuit and three-circuit. The electrical wires in each of electrical installation can perform one of the following three functions: live, neutral and earth.

Here we will explain how to differentiate one from the other thanks to the colour coding of electrical cables.

It should be noted that internally the three cables are the same, differing only in the colour of the sheathing.

IEC Standard 60446

This is the International Electrotechnical Commission standard which indicates the colours and/or labels to identify each type of cable. It is the standard most commonly used in Europe.

Black, brown, red, orange, yellow, green, blue, violet, grey, white, pink and turquoise colours can be used. Green and yellow may also be used as long as they do not cause confusion.

Colour combinations can also be used, but the green/yellow combination can only be used to identify earth.

Live wire colour

In the past, the colour brown or black used to be used to identify the live cable. Nowadays, the standard indicates that, in single-circuit installations, the colour brown should be used. This cable is labelled as L.

This colour also identifies the first live cable (L1) in a three-circuit installation, the following cables being black (L2) and grey (L3).

It is not surprising to find that in some cases, grey wiring is also used to identify live in a domestic installation.

Neutral wire colour

Neutral, according to IEC 60446, remains the colour blue as in previous versions of the standard. It is labelled N..

Earth wire colour

The earth wire is described as green-yellow. In most cases it is actually green with a yellow line. These conductors are not marked..

Old wiring colours in the United Kingdom

Although they now follow the regulations of the International Electrotechnical Commission, this was not the case a number of years ago. For this reason, it is possible to find installations with other cable colours, for example:

• Live: Red (single-circuit). Red, yellow and blue (three-circuit).
• Neutral: Black.
• Earth: Green-yellow.

AC Power Cable Colour Chart