A fuse board is a major piece of electrical equipment designed to provide overload and fault protection to individual final circuits (for example, the cooker, plug sockets, Lights, shower, etc).
Overloading can occur due to a fault (short circuit) in a circuit or due to excessive power consumption. Whatever the cause, whenever an overload occurs and power consumption exceeds the fuse rating of the circuit, the fuse blows to protect the integrity of the affected circuit.
In addition to the overload and fault protection, modern-day fuse boards, now widely known as consumer units, are designed to provide extra layers of protection from fatal electrical hazards.
Consumer units are equipped with a combination of RCDs (residual current devices) and MCBs (miniature circuit breakers) or standalone RCBOs (residual current breakers with overcurrent) and SPDs (surge protection devices).
The RCDs and RCBOs are life-saving devices which protect humans or livestock from electrocution, while the MCBs are the modern equivalent of the old rewireable or cartridge fuses. The SPD protects sensitive household electrical equipment from external power surges, which usually occur due to lightning striking. Although, there are other causes of occasional external power surges.
The new consumer units are constructed of fire-rated, non-combustible material, usually metal, to prevent the spread of accidental electrical fires.