What is an RCCB?
An RCCB (Residual Current Circuit Breakers) is a type of RCD (Residual Current Device) that is used for electrical protection, in particular to people. They are designed to rapidly disconnect the circuit (within a few milliseconds) when it detects that the electric current is not balanced between the phase conductor. This is in particular during the earth leakage situation when a person comes into contact with a live wire.
A typical specification of 30mA or less leakage is used for home protection.
An RCCB must be used with an MCB to give a full protection as RCCB do not offer short-circuit or overload protection.