A home extension is a significant investment, and the electrical installation is one of the most important elements to get right. Poor electrical planning causes problems for years — too few sockets, inadequate lighting, or circuits that can't support the intended use of the space.
Getting the Electrician Involved Early
The best time to involve your electrician is at the planning stage — ideally before your architect finalises drawings. This allows you to:
- Position sockets, switches and lighting correctly from the start
- Design circuits that suit how the space will actually be used
- Avoid structural conflicts (e.g., cable runs through structural elements)
- Cost the electrical work accurately before committing to the project
First Fix and Second Fix
Like all new-build electrical work, extension electrics happen in two phases:
First fix — installing cables and back boxes before plastering. This is done after the walls are up and roof is on, but before insulation and plasterboard.
Second fix — fitting sockets, switches, light fittings and connecting everything up, done after plastering and typically after decoration.
How Many Sockets Do You Need?
As a minimum guide for a living room extension:
- 4–6 double sockets around the perimeter
- 2 sockets on the TV wall (or more if wall-mounting a TV with media unit)
- USB sockets at least in one or two positions
- Outdoor socket if the extension has external access
For a kitchen extension, requirements are higher — kitchen circuits need to be planned carefully around appliances and worktops.
Lighting Design
Think about your lighting scheme at planning stage:
- Downlights: how many, what spacing? (General rule: one downlight per 1–1.5m² of floor area for even lighting)
- Feature lighting: pendants, wall lights, under-cabinet lighting?
- Dimmers: which circuits need dimmer capability?
- Smart lighting: are you planning smart controls?
Connecting to the Existing Installation
Your extension circuits will need to connect back to your existing consumer unit. If the consumer unit is old or has no spare ways, an upgrade may be needed at this stage — which is often a convenient time to do it anyway.
Part P Compliance
All electrical work in extensions is notifiable under Part P. Your electrician should be NICEIC registered (or registered with another scheme) to self-certify the work.
Onyx Electrical Solutions plans and installs electrical installations for extensions across Greater Manchester. Call 07000 000000 for a free consultation.