How UK Home Electrics Are Laid Out

UK homes are supplied with single-phase 230V AC from the distribution network. The supply enters through a sealed meter (owned by your energy supplier) and feeds your consumer unit (CU) — the grey or white box you'll find under the stairs, in a cupboard, or on a wall.

The Consumer Unit

MainsConsumerUnitRing main (32A)Lighting (6A)

Each MCB (Miniature Circuit Breaker) in the CU protects one circuit. If a fault occurs, the MCB trips — disconnecting only that circuit, not the whole house.

The Circuits

Most UK homes have:

  • Ring final circuit — powers all standard socket outlets (13A sockets) in a room or floor. Runs as a ring: one cable leaves the CU, loops around the sockets, and returns to the same MCB.
  • Lighting circuit — powers ceiling lights and their switches. A radial (single-run) circuit, usually 6A.
  • Radial circuits — single-run circuits for higher-load appliances (kitchen, utility room).
⚡ Open the Design canvas to try building a circuit

What You Can Do Yourself

Under Part P of the Building Regulations, some electrical work is notifiable (requires a registered electrician or local authority approval) and some is not. As a DIYer, you can generally:

  • Add a socket or light to an existing circuit (non-notifiable)
  • Replace like-for-like fittings (non-notifiable)

You cannot do the following yourself without notification:

  • Install a new circuit from the consumer unit
  • Work in kitchens, bathrooms, or outdoors (special locations)

See Part P — what DIYers can & can't do for the full rules.