The flow of current through electrical facilities always involves risks. Poorly insulated equipment, faulty wires and incorrect use of an electrical devise cause currents to flow through the wrong path (i.e., through the insulation) to the earth. This current is called ' Leakage Current '.
Earth Leakage is an electrical hazard and is responsible for electrical shocks and fire risk. Earth Leakage and its associated hazard can be prevented by residual current device (RCD), similar to that of a residual current circuit breaker (RCCB), also popularly known as Earth Leakage Circuit Breaker (ELCB).