Most of the expensive mistakes in a renovation's electrics are made before anyone picks up a pair of pliers.
They are made in the gap between deciding to renovate and deciding where things go, because that gap is usually filled by a builder’s programme rather than by anyone thinking about how the rooms will actually be used.
This is a guide to getting that part right: when to involve an electrician, what has to be decided early, what happens in what order, and what you should be left holding at the end.
Key Takeaways
- The electrical layout must be agreed before first fix, not after plastering
- Involve an electrician at the design stage, not when the builder is ready
- Expect two visits: first fix before plastering, second fix after decorating
- The power goes off in stages, not for the whole project
- You should end up with a certificate and a labelled board, not just working sockets
When To Involve An Electrician
Earlier than most people do. The useful moment is when the layout is being decided, not when the builder says they are ready for the sparks.
The reason is simple. Once a wall is plasterboarded and skimmed, moving a socket means cutting it open and making it good again. A decision that costs nothing on a drawing costs a day and a redecoration once the wall is closed. Every renovation we go into late has at least one of these.
It is also when the awkward questions are cheapest to answer. Is the existing consumer unit going to cope with what you are adding? Is the incoming supply big enough for an induction hob, a heat source and a car charger? Does the circuit feeding the kitchen date from a period when a kitchen meant a kettle and a fridge? Those answers change the budget, and you want them before you have committed to a kitchen rather than after.
What Gets Decided Before First Fix
First fix is the stage where cable goes in while the walls are open. Everything below has to be settled before it starts, because afterwards it is all expensive:
- Socket positions and quantities, room by room, including the ones you will want and have not thought of: bedside, desk, kitchen island, hallway for a vacuum
- Where the furniture is going, because a socket behind a wardrobe is a socket you do not have
- Lighting layout and switching, including which lights are controlled from where, and whether any of it needs dimming
- Anything hard-wired: hob, oven, extractor, shower, heating controls, outside lighting
- Data and networking, which is far easier now than later and almost always regretted when skipped
- Whether a charge point, solar or battery storage is coming, now or in a few years
That last one matters more than people expect. Running a cable or leaving capacity at the board while the walls are open costs very little. Retrofitting around a finished house costs a great deal more. If an EV charger is anywhere in your thinking, say so at this stage even if you are not buying the car yet.
The Order Things Happen In
A renovation’s electrics happen in two visits, separated by everyone else’s work.
First fix. Cables are run through open walls, floors and ceilings to every position agreed, back boxes are fitted, and the circuits are left ready. Nothing is connected and nothing works yet. This is the stage that locks in your layout.
Plastering, then the rest of the build. We are off site. Walls get closed, floors go down, decorating happens.
Second fix. Sockets, switches, light fittings and any hard-wired appliances are fitted and connected, the consumer unit work is completed, and the whole installation is tested and certified.
The gap between the two is usually where a renovation programme slips, and it is worth understanding that the second fix date depends on the plasterer and the decorator rather than on us. We will tell you what we need in place before we come back.
How Long Is The Power Off?
Not for the whole job, which is the thing most people are bracing for.
For most of first fix the existing circuits can stay live, because the new cable is not connected to anything yet. The power goes off for specific pieces of work: tying new circuits into the board, changing the consumer unit, and testing at the end.
If you work from home, say so at the first visit rather than on the morning it matters. We can usually plan the board work for a specific day, or keep a working circuit live while the rest is dealt with. It is a straightforward thing to arrange in advance and a very awkward one to arrange at nine in the morning.
Do You Need A Rewire Or Not?
Renovation is the point where this question gets asked properly, and the honest answer is that it depends on what is behind the plaster rather than on the age of the house.
Sometimes a renovation is the right moment for a full rewire: the walls are open anyway, the disruption is already happening, and doing it later means doing the damage twice. Sometimes the existing circuits are perfectly sound and only the areas being changed need new work, which is a partial rewire and considerably cheaper.
What settles it is testing, not guessing. We test the existing circuits, tell you what the results show, and quote for the work the installation actually needs. If you want to know what tends to point towards a rewire, our guide on the signs a house may need rewiring covers it.
A related point worth being clear about: a new consumer unit does not improve the cable behind it. On sound wiring it is a sensible upgrade. On failing wiring it tends to start tripping, because modern protection detects faults the old board never could. That is the new board working, not failing, and it is why we test before quoting rather than after fitting.
What You Should Have At The End
When the work is finished you should be left with more than sockets that work:
- An Electrical Installation Certificate covering the work carried out
- A labelled consumer unit, so the next person to look at it knows what is what
- Any manufacturer documentation for equipment installed
- A walkthrough of anything that is not self-explanatory
Keep the certificate. It is what you will be asked for when you sell, and it is the only proof that the work was tested rather than simply finished.
How We Approach Renovation Work
We work with homeowners and small-scale developers on renovations, extensions and new builds, and the most useful thing we do is usually the conversation before the quote.
We will come and look at the property, go through the layout room by room, test what is already there, and tell you honestly which parts of the existing installation can stay. Then you get a free, itemised quote covering the full scope rather than a figure that grows once the walls are open.
As NICEIC Approved Contractors with over twenty years of experience, everything is tested, certified and left tidy, with floor protection down before we start and all waste taken away. We carry out electrical installations across Salisbury, Downton and the surrounding villages.