New rooms are the easy part. The question that decides how an extension's electrical package is scoped is what the existing installation can support — capacity at the board, condition of the circuits being extended, and whether bonding is adequate.
Test the existing first
We test before designing. If the existing board is full, or circuits show poor insulation resistance, extending them simply spreads the problem into new plasterwork. It is far cheaper to know at the drawing stage.
Designing the new space
Extensions are usually open-plan, which means switching and socket positions need thinking about in terms of how the space will be used rather than by copying a standard layout.
- Switching at every natural entry point to the space
- Sockets set against the intended furniture layout
- Lighting zoned so the whole space need not be lit at once
- External supplies and lighting on the new elevation
- Data and TV routes decided before plasterboard
Certification and coordination
New circuits are notifiable, and you will receive a full installation certificate. We coordinate first and second fix with the builder's programme and will attend for building control inspections where required.
Common questions
- Can the extension run off existing circuits?
- Sometimes for lighting, rarely for sockets. Testing and load assessment decide.
- Will the board need replacing?
- Only if capacity or protection is inadequate. We will tell you at survey.
- Do you coordinate with the builder?
- Yes, directly, on both fix dates.
- Are underfloor heating supplies included?
- We provide and certify the electrical supply; the heating system itself is usually its own installer.
Send the plans and we will scope the electrical package alongside your builder's programme.
Related guides
- Rewiring During a Renovation, How to Sequence ItA renovation is the cheapest time a house will ever be rewired.
- Electrics for a Kitchen RefitThe kitchen carries more electrical load than any other room, and gets the least planning time.
- Powering a Garden Office or OutbuildingA garden office is a small installation in its own right, not a long extension lead.