Ring Main Circuit Breaker Size

This design reduces the consequences of faults and enables the use of smaller diameter wire than would be used in a radial circuit of equivalent ampacity.

Ring main circuit breaker size. Cable rating for cables used in a ring main must be no less than two thirds of the rating of the ring main s protective device. Well he said because a piece of 2 5mm2 can only take circa 26 amps and if the ring main broke at any point it would effectively make it two radials and it would be protected by a 32 amp breaker if done the traditional way. A 30a circuit breaker can safely carry the exact 30a current but nec suggests 80 as a safe current limit as compared to the rated current. 75 m 2 area 4 0 2 5 30 or 32.

Ring main mcb size. In practice meeting this requirement is rarely an issue. The size of a circuit breaker is the maximum current that can pass through the breaker without tripping the circuit and causing a loss of power. The ring is fed from a fuse or circuit breaker in the consumer unit.

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. A ring final circuit or ring circuit informally also ring main or just ring is a wiring technique developed and used in the uk that uses two conductors for each of live neutral and earth to supply each connected socket or other load. Ring circuits are commonly used in british wiring with socket outlets taking fused plugs to bs 1363 because the breaker rating is much higher than that of any. Discussion in electrics uk started by jaffadutch 8 jul 2005.

This topic originated from the how to page called types of electrical circuits. As circuit breakers cbs and overcurrent protection devices ocpd are designed for 100 rated current i e. Hi guys recently i had an issue with a ring main in my flat either the circuit was over loaded or the connection at the breaker was poor. Usually the protective devices used on a ring main will be a 30 a fuse 30 a breaker or 32 a breaker and the cables are usually 2 5mm in size.

In other words the breaker controlling a circuit should be 125 percent of the continuous load maximum current expected to last for three hours or more and 100 percent of the non continuous load. Either way it ended up with a burnt out breaker with black scorch marks on the top and melted cables by the breaker. Circuit breaker and conductor selection capacity conductor size copper circuit breaker capacity a main mm 2 earth mm 2 up to 600 w 1 5 1 5 6 600 1 200 w 1 5 or 2 5 1 5 10 1 200 1 800 w 2 5 or 4 0 2 5 16 a1 ring circuit serves max. Assuming your cable size is 2 5 mm squared twin and earth the sockets should be on one of two sized breakers depending which way they have been wired 32 amp for a ring main and 16 amp for a radial circuit i do hope this helps.