Description
The ring starts at the consumer unit (also known as fuse box, distribution board, or breaker box), visits each socket in turn, and then returns to the consumer unit. The ring is fed from a fuse or circuit breaker in the consumer unit.
Ring circuits are commonly used in British wiring with fused 13 A plugs to BS 1363. They are generally wired with 2.5 mm2 cable and protected by a 30 A fuse, an older 30 A circuit breaker, or a European harmonised 32 A circuit breaker. Sometimes 4 mm2 cable is used if very long cable runs (to help reduce volt-drop) or derating factors such as thermal insulation are involved. 1.5 mm2 mineral-insulated copper-clad cable (known as pyro) may also be used (as mineral insulated cable can withstand heat more effectively than normal PVC) though more care must be taken with regard to voltage drop on longer runs.
Many lay people in the UK refer to any circuit as a ring and the term lighting ring is often heard from novices. It is not unheard of to see lighting circuits wired as rings of cable (though usually still with a breaker below the cable rating) in DIY installations.
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