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 workplaces, often installed in electrical panels or as plug-in devices. They are essential for ensuring safety in areas with high moisture, such as bathrooms and kitchens, where the risk of electric shock is greater. Regular testing of RCDs is recommended to ensure they function correctly.