Explain how a single-phase earth leakage circuit breaker will operate when a fault current is detected in an electrical installation.

A single-phase earth leakage relay (Residual Current Device) operates by continuously monitoring the current flowing through the live and neutral conductors. In a healthy circuit, these currents are equal and opposite, resulting in a zero net current. If an earth fault occurs, some current leaks to earth, creating an imbalance between the live and neutral currents. When this imbalance (residual current) exceeds a predetermined trip threshold (e.g., 30 mA), the relay rapidly trips, disconnecting the electrical supply to the faulty circuit and preventing electric shock.