Electric cable and flex

• Brown is Live
• Blue is Neutral.
• Earth will be a bare wire that needs fitting with yellow-and-green sleeving.

If the cable has four cores (used for two-way switching) the colour coding will be:

• Brown*
• Black*
• Grey*
• Earth will be a bare wire that needs fitting with yellow-and-green sleeving.

*Any or all may be live.

• Red is Live.
• Black is Neutral.
• Earth will be a bare wire or may be fitted yellow-and-green sleeving.

If the old cable has four cores as used for two-way switching, the colour coding will be red, yellow, blue (any or all may be live) and a bare earth wire.

Cable comes in different sizes and is classified by the area of the cross-section of the cores and can range from 1mm² to 10mm². The size of the cable you require depends on the current supplied by the circuit. Below is a list of common cable sizes and what they are used for. If you are not sure what size of cable you need, seek advice from a professional electrician.

As mentioned above flex also comprises PVC sheathing that protects colour-coded insulated conductors or cores. The PVC sheath of standard flex can be damaged if it comes into contact with a hot surface, there fore portable appliances that produce high levels of heat such as an electric iron or toaster, may well be fitted with rubber sheathing heat-resistant up to 85°C or a braided flex.

The cores in three-core electric flex are colour coded as below:

• Brown is Live
• Blue is Neutral
• Yellow-and-green is Earth

The cores in two-core electric flex are colour coded as below:

• Brown is Live
• Blue is Neutral

For non-metal light fittings and double insulated appliances such as some power tools.

Use for all appliances that need to be earthed.

There is also 1.5mm² heat resistant flex for use with immersion heaters.

• Television and radio wiring uses coaxial cable, which is capable of transmitting at a high frequency.
• Telephone cable contains six colour-coded conductors.
• Computer networks require Ethernet cable and modem cable.