10-04-2017, 09:33 PM
The radial circuit
Two types of radial circuit are permitted for socket outlets. In neither case is the number of sockets to be supplied specified, so the number will be subject to the constraints of load and diversity. The two standard circuits are:
1. - 20 A fuse or miniature circuit breaker protection with 2.5 mm live and 1.5mm protective conductors (or 1.5 mm if m.i. cable) feeding a floor area of not more than 50 m . If the circuit feeds a kitchen or utility room, it must be remembered that a 3 kW device such as a washing machine or a tumble dryer takes 12.5 A at 240 V and that this leaves little capacity for the rest of the sockets.
2. - 32 A cartridge fuse to B888 or miniature circuit breaker feeding through 4 mm live and 2.5 mm protective conductors (or 2.5 mm and 1.5 mm if m.i. Cable) to supply a floor area no greater than 75m .
The arrangement of the circuits is shown in . 4mm may seem to be a large cable size in a circuit feeding 13 A sockets. It must be remembered, however, that the 2.5 mm ring circuit allows current to be fed both ways round the ring, so that two conductors are effectively in parallel, whereas the 4 mm cable in a radial circuit must carry all the current.
