What safety devices are used in domestic electrical systems?

Domestic electrical systems use safety devices like circuit breakers, fuses, residual current devices (RCDs), and earthing systems.

Circuit breakers are automatic switches that protect electrical circuits from damage caused by overload or short circuit. When the current flowing through the circuit exceeds a safe level, the circuit breaker trips, cutting off the electrical supply. This prevents overheating and potential fires. Circuit breakers can be reset manually after the fault is fixed, making them reusable.

Fuses are simpler devices that also protect against overcurrent. A fuse contains a thin wire that melts when the current exceeds a certain level, breaking the circuit and stopping the flow of electricity. Unlike circuit breakers, fuses need to be replaced once they have blown. They are often found in plug tops and older electrical systems.

Residual Current Devices (RCDs) are designed to protect against electric shock. They work by detecting any difference between the live and neutral wires. If there is an imbalance, it indicates that some current is leaking, possibly through a person who has touched a live part. The RCD quickly cuts off the power, reducing the risk of serious injury or death. RCDs are often found in modern consumer units (fuse boxes) and can also be used in individual sockets.

Earthing systems are another crucial safety feature. They provide a path for electrical current to flow safely to the ground in case of a fault. This helps to prevent electric shocks. Metal parts of electrical appliances are connected to the earth wire, so if a live wire touches the metal casing, the current will flow to the ground instead of through a person.

These safety devices work together to ensure that domestic electrical systems are safe to use, protecting both people and property from electrical hazards.