Power circuits (page 2)

This material is " for information purposes " only. Strict rules govern what electrical work can be done without notification and inspection. Read more...

Back to page 1

Radial circuit

These circuits have a twin and earth cable running from the consumer unit to each of the socket outlets or fused connection units in turn, one after another, but it stops at the last one. There is no return cable back to the consumer unit from the last socket or unit. There is no limit to the number of socket outlets / fused connection units supplied, and spurs may be added. The cable used and the fuse required may differ from a ring main, depending on the application. Large appliances often have to be on their own circuit. Be sure you know the regulations before attempting any work. These include the following:

For a floor area up to 20 m sq, 2.5 mm sq cable is used and the circuit is protected by a 20 amp fuse. The maximum length of cable is 35 m when a cartridge fuse is fitted and 33 m with an MCB.

For a floor area up to 50 m sq, 4 mm sq cable is used and the circuit is protected by a 30 amp cartridge fuse or 32 amp MCB. The maximum length of cable is 38 m when a cartridge is fitted and 15 m with an MCB. It should be noted that the rewireable fuse is not allowed in this instance.

Large appliances like cookers must be supplied by their own separate radial circuit.

• The mains supply
• Lighting circuits
• New sockets