Socket Rings: Three separate ring circuits are often used for sockets around the home, one upstairs, one downstairs and one for the kitchen. Each separate ring is fed from the consumer unit via an individual 32A type B circuit breaker and a separate 30mA RCCB via a split load board or a combined 32A/30mA RCBO device.
It is wired using two x 2.5 mm Twin and Earth PVC cables with the outgoing cable going to each socket on the ring and returning to the consumer unit where it connects in the same terminals on the circuit breaker, neutral bar and CPC bar as the outgoing cable.
Branches know as spurs may be taken off the ring from any socket or by breaking into one of the cables of the ring. They can either be non-fused which connect directly to the ring or can be a fused spur which connect to the ring via a switched or unswitched-fused connection unit. The number of points allowed off each type spur differ…
Non-fused spur can only have one twin socket or one fixed appliance and a fused spur can have as many sockets as you require but care should be taken to ensure that the total load does not exceed the 13A fuse within the switched or unswitched-fused connection unit. This 13A max load may be okay in a conservatory but not in the kitchen. The total number of spurs should not exceed the total number of sockets on the ring.
Socket Radials: Can be used where only a few sockets may be required, such as a conservatory or garage. Fed from the consumer unit via an individual 16A type B circuit breaker and a separate 30mA RCCB via a split load board or a combined 16A/30mA RCBO device. It is wired using 2.5 mm Twin and Earth PVC cable and goes to each socket and stops at the last socket and does not return to the consumer unit.
Additional and very useful information concerning the do’s and don’ts of ring and radial circuits can be found in Appendix 15 of BS7671:2018