The consumer unit, commonly known as the fuse box, is the centre of a home wiring installation. It is usually mounted close to the electricity meter. A modern consumer unit as in the picture above houses modular electrical devices called circuit breakers. There are four main kinds of circuit breakers in a common household consumer unit: Main switch, MCB and RCD.

The main switch functions like a master switch that can isolate the incoming electrical power supply to the house.

After the main switch, the incoming power supply is split into several circuits such as power, lighting and appliances.

Each circuit is protected and controlled by a Miniature Circuit Breaker (MCB). When the circuit draws current above the MCB rated current, the MCB trips and turns off the power to protect the devices on that circuit.

In modern homes, consumer units are also equipped with a Residual Current Device (RCD). An RCD is a sensitive safety device that switches off the electricity when it detects a fault. It is designed to prevent electrical shocks & fire caused by earth faults. Circuits that power outdoor devices must be installed with RCD protection.

Every circuit breaker should be labelled carefully so that the circuits can be identified and isolated when work needs to be undertaken on them.