If you’re extending or renovating, the electrics happen in two visits with a long gap between them — and getting the timing right with your builder is the difference between a smooth job and cables in the wrong place. Here’s how it sequences, so you can plan it properly.
First thing to know
Electrical work on an extension splits into first fix and second fix. First fix happens once the structure is up, roof on and walls are open but not yet plastered: we run all the cables, back-boxes and any pipework for lights and sockets while everything is accessible. Then the plasterers move in. Second fix happens near the end, once decoration is nearly done: we fit the sockets, switches, lights, connect it all back to the fusebox, then test and certify. The key thing your builder needs from us is a first-fix slot booked before the plasterer — miss it and cables get buried or chased back in at extra cost. We’ll also tell you early if the extension’s extra load means your existing fusebox needs upgrading, so it isn’t a surprise at the end.
Safety note
Agree socket, switch and light positions before first fix, on site, with a pencil on the wall — not from a plan on a screen. Moving a socket after plastering means breaking open a finished wall. Ten minutes walking the rooms with us before we run a single cable saves the most common and most annoying extra cost on any extension.
When to call us
Call us as soon as you’ve got a builder and a start date — not the week the plasterer’s booked. We’ll work to your builder’s programme, hit the first-fix and second-fix windows, handle any fusebox upgrade, and issue the certificate your building control sign-off needs. Bring us in early and the electrics become the part of the project nobody has to worry about.
Want a price for this?
Get an honest range in two minutes with the instant estimate — no contact details needed.