Second Fix Electrics: Sockets, Lights, and Final Wiring

Your electrician will quote you a number. You'll pay significantly more than that number. This isn't a scam. It's how second fix electrics works on every extension project, and understanding why is the difference between a budget blowout that blindsides you and one you planned for.

Second fix is when all the cables your electrician buried in the walls during first fix finally get connected to something visible. Faceplates go onto sockets and switches. Light fittings get hung. The consumer unit gets completed, tested, and certified. Your extension goes from a shell with wires poking out of walls to a space with working power.

The work itself takes 3-5 days for a typical extension. But the invoices will arrive over weeks or months, because second fix electrics rarely happens in one clean visit.

What's actually in the quote

The quote your electrician gave you at the start of the project covers a defined scope: a certain number of sockets, switches, and light fittings connected to the circuits wired during first fix. Standard white accessories are usually included. That's it.

What the quote almost certainly doesn't include:

• Chrome, brushed steel, or matt black faceplates (you'll pay the difference over standard white)
• Smart thermostats and their wiring
• Smart doorbells and their transformers
• Outdoor lighting circuits
• Under-cabinet kitchen lighting
• Island or peninsula power coming up through the floor
• USB-C integrated sockets
• TV trunking and data points
• Shelving or display lighting
• Any fittings the electrician buys on your behalf

Each of these is individually reasonable. A smart thermostat adds £100 – £150 in materials plus an hour or two of labour. A pair of outdoor porch lights might be another few hundred. Under-cabinet lighting, a shelving transformer, a doorbell transformer. On their own, none of them feel like a problem.

They compound.

Clarify one thing before any work begins: who is buying materials? Some electricians supply everything and add it to the invoice. Others expect you to buy sockets, switches, and light fittings yourself. If you don't agree this upfront, you'll end up paying retail prices on components your electrician picked up from the wholesaler, marked up.

The scheduling dance

Second fix electrics sits in a tight sequence with three other trades, and getting the order wrong wastes everyone's time.

The plasterer must finish first. Faceplates go onto flat, plastered walls, and if the plaster isn't dry and firm, the electrician can't fix backing plates flush. Gaps between faceplate edges and wall are a common defect that building control and NHBC inspectors look for.

The electrician needs to finish before the decorator, not because the decorator can't work around missing faceplates (they can, and a good decorator often prefers to paint with plates off for a cleaner cut-in) but because if the electrician fits the plates after the paint is dry, the freshly decorated area around each plate gets scuffed during installation and you are looking at touch-ups. The clean sequence is: electrician fits back-boxes and dresses cables at first fix, decorator paints with faceplates either temporarily loosened or not yet fitted, electrician returns to fit and test plates last.

The kitchen fitter needs the electrician to have connected island sockets, under-cabinet wiring, and any integrated appliance feeds before fitting units around them. But the electrician also needs the kitchen fitter to have the island in position before making final connections there. This creates a chicken-and-egg problem that requires coordination, not just a schedule.

If your second fix falls over Christmas or a bank holiday period, expect delays. Electricians have the same holidays as everyone else, and the ones who work through Christmas charge premium rates. Plan around it or accept the cost.