A residual-current device/breaker (RCD), or residual-current circuit breaker (RCCB) or Safety Switch, is an electrical wiring device. It gets installed in the electrical panels of residential and industrial buildings and disconnects a circuit whenever it detects that the electric current between the energized conductor and the return neutral conductor is unbalanced. Such an imbalance may indicate current leakage through the body of a person who is grounded and accidentally touching the energized part of the circuit. A deadly shock can result from these conditions. RCDs are designed to disconnect quickly enough to prevent injury caused by such shocks. They also can prevent development of causing fire conditions.