An Earth Leakage (ELCB) is a safety device used in electrical installations with high Earth impedance to prevent shock. It detects small stray voltages on the metal enclosures of electrical equipment, and interrupts the circuit if a dangerous voltage is detected. When an electric shock occurs, or leakage current in grid exceeds the stipulated values, the E/L cuts off the fault power in a very short time to protect the safety of humans and electrical equipment. it can also function as a non-frequent switch for circuits.