What is an RCBO?

A mechanical switching device designed to make, carry and break currents under normal service conditions and to cause the opening of the contacts when the residual current attains a given value under specified conditions. In addition it is designed to give protection against overloads and/or short circuits and can be used independently of any other overcurrent protective device within its rated short circuit capacity.

When should I use an RCBO?

An RCBO is a combination of an MCB (mini circuit breaker) and RCD (Residual Current Device). Since an RCBO provides protection against overloads and short circuits (MCB) and earth leakage (RCD) it is used for vital circuits that should not be 'switched off' by an RCD when there is a fault on a different circuit protected by that RCD. ..... You would not, for example, want your freezer in the garage, security system or most importantly fire alarms disabled because there is a fault on your lighting circuit.

RCBOs can also be used to make an older 16th edition fuse board compliant with the new 17th edition regulations. Since an RCBO provides earth leakage protection on each circuit you can simply replace the MCBs on your fuseboard which are not currently protected by and RCD.