COMMON CONSUMER UNIT DEVICES AND CONFIGURATIONS
MAIN SWITCH
RCD
MCB
RCBO
AFDD/RCBO
MAIN SWITCH:
The main switch isolates the incoming supply to the whole consumer unit. This can only be operated manually.
RCD (Residual Current Device):
An RCD is a device designed to provide protection against electrocution or electrical fires, by isolating all the circuits protected by that device when it detects an earth leakage fault.
Often an RCD will protect a number of circuits within the consumer unit. In some older installations it can be used as a main switch which means the RCD protects the entire installation.
For more information regarding RCD protection, please click here.
MCB (Miniature Circuit Breaker)
An MCB device operates upon detection of a short circuit fault or overload. An installation will be divided into individual circuits, with a suitably sized circuit breaker protecting it.
RCBO (Residual Current Circuit Breaker with Overload Protection)
An RCBO device incorporates the functions of an RCD and an MCB, meaning they will operate upon detection of an earth leakage fault, short circuit fault or overload.
RCBOs protect individual circuits, meaning that in the event of a fault, only the affected circuit will be isolated and the rest of the installation will remain energised.
AFDD/RCBO (Arc Fault Detection Device/ Residual Current Circuit Breaker with Overload Protection)
An AFDD/RCBO device incorporates the functions of an AFDD, an RCD and an MCB, meaning they will operate upon detection of an arc fault, an earth leakage fault, short circuit fault or overload.
AFDD/RCBOs protect individual circuits, meaning that in the event of a fault, only the affected circuit will be isolated and the rest of the installation will remain energised.