Consumer unit
The distribution board of a domestic installation. A main switch, residual- protection and a row of circuit devices on a DIN rail split the incoming supply into individually protected final circuits. Modern UK consumer units sit in non-combustible enclosures and increasingly give every circuit its own instead of sharing across banks.
Where Consumer unit fits in the learning path
The Installation section covers these units:
- Wiring Systems & Enclosures
- Cable Selection & Circuit Design
- Earthing, Bonding & Consumer Units
Curriculum mapping: C&G 2365 Units 203/204/305.
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An automatic switch that turns a circuit off when too much current flows, whether a slow overload or a sudden short circuit. It has replaced the rewirable fuse in modern boards. Each one is chosen by its current rating, such as 6 A for lights or 32 A for sockets, and by its type: B for most home circuits, C or D where equipment draws a big surge as it starts.
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MCB — Miniature Circuit Breaker
An automatic switch that turns a circuit off when too much current flows, whether a slow overload or a sudden short circuit. It has replaced the rewirable fuse in modern boards. Each one is chosen by its current rating, such as 6 A for lights or 32 A for sockets, and by its type: B for most home circuits, C or D where equipment draws a big surge as it starts.
Read the MCB entryRCBO — Residual Current Breaker with Overcurrent protection
A single DIN-rail device combining an RCD and a circuit breaker, so one module gives a circuit both residual-current protection and overload/short-circuit protection. The practical win is selectivity: a fault on one circuit trips that circuit alone, instead of dropping every circuit that shares a bank RCD.
Read the RCBO entrySPD — Surge Protective Device
A device that diverts brief, high-voltage spikes — from lightning activity or heavy switching — safely to earth before they reach sensitive equipment. Usually fitted at or near the consumer unit, SPDs have moved from a luxury to an expected part of new installations as homes fill with vulnerable electronics.
Read the SPD entryNotifiable work
Domestic electrical work that must be notified under Part P of the Building Regulations in England and Wales. Wales covers more kinds of work than England; Scotland and Northern Ireland run their own systems. It includes a new circuit, a replacement consumer unit and some work in bathrooms. There are two lawful routes: an electrician registered with a competent-person scheme certifies and notifies it, or the householder tells local authority building control before starting and pays for it to be inspected.
Read the Notifiable work entryA definition is a start. Using it in a real question is where it sticks.