Which protection device automatically disconnects the supply in case of earth faults?

The Earth Leakage Circuit Breaker (ELCB) is the correct choice because it is specifically designed to monitor the current flowing through the live and neutral circuits and can automatically disconnect the electrical supply when it detects an imbalance that suggests an earth fault. This imbalance indicates that some current is leaking to the ground, which could pose a serious shock hazard or fire risk. By disconnecting the supply, the ELCB helps protect both people and equipment from the potential dangers of these faults.

In contrast, while fuses and circuit breakers also serve protective functions, they primarily protect against overcurrent situations rather than specifically monitoring for earth faults. Fuses will melt to interrupt the circuit under excessive current conditions, and circuit breakers will trip on overcurrent as well but do not specifically detect earth faults. Surge protectors are designed to protect against voltage spikes and transients rather than detecting or disconnecting in the event of earth faults. Thus, ELCBs are uniquely suited for detecting and responding to earth fault conditions, making them the preferred device for this purpose.