A Residual Current Device (RCD) is a safety device designed to prevent electric shock and electrical fires. It works by monitoring the flow of electricity in a circuit and quickly disconnecting the power if it detects an imbalance, which may indicate a fault or leakage of current. This helps protect people from electric shocks and reduces the risk of electrical fires caused by faulty wiring or appliances. RCDs are commonly used in homes and commercial buildings as part of electrical safety systems. They can be installed as standalone devices or integrated into circuit breakers. Regular testing of RCDs is essential to ensure they function correctly and provide the necessary protection against electrical hazards.