ELCB

Short for Earth Leakage Current Breaker. Detects earth leakage.

Current through the body, not voltage, is what harms people. Because of that RCCBs are preferred instead of ELCBs.

Mechanism

Has a trip coil. Trips when voltage difference between the frame earth and the reference earth exceeds the rated voltage (usually ). The trip coil is energized by the voltage difference, and the spring-loaded contact is released which breaks the circuit and cuts off power. Up to about has been traditionally considered as a safe voltage.

2 earth terminals are required for the proper operation.

• Frame earth: to which all non-conducting metallic parts of equipment are connected
• Reference earth