Residual Current Circuit Breaker

An RCCB (residual current circuit breaker) provides protection against residual current faults, most commonly referred to as earth leaks or (in the USA) ground faults. However, RCCBs can also be used to protect three phase systems where the fault may be to earth but could also be between live phases.

An RCCB only protects against residual current faults (and specifically not overload or short circuit faults) and should therefore be used in conjunction with one or more MCBs.

The residual current sensitivity (in mA) is the key parameter when specifying an RCCB and defines the fault level you want the RCCB to detect and protect against, with 30mA being the most common in the UK and Europe.

The RCCB also has a main current rating (usually 25A – 63A). It is critical to understand this is nothing to do with its protection capabilities and simply states the maximum continuous circuit current the RCCB can carry under normal working conditions. So, for example, you could use a single 40A RCCB to provide residual current fault protection for 4 x 10A separate MCB circuits.

Both 6kA and 10kA short circuit ratings available. This describes the maximum short circuit the RCCB can withstand and still be resettable. However, this rating is applicable only when used in conjunction with an appropriate MCB (or fuse).

The RCCB device will detect and trip against electrical leakage currents, so providing protection against electric shock caused by indirect contacts.

We have a range of RCCBs available, and all offer the opportunity to download a data sheet for further information on each.