Planning the electrics for a renovation: decide before the plasterer arrives.
The electrics for a renovation should be planned before the builder is booked, not after the walls are open. Almost every electrical decision in a renovation is cheap to make on paper and expensive to change once the plaster is on, so the order matters: inspect what you have, decide what the house needs to do for the next twenty years, then let the electrician wire it in one visit rather than three.
Start with an inspection, not a wish list.
Before anyone draws a socket on a plan, find out what the existing installation can carry. An Electrical Installation Condition Report tests the circuits behind the walls and tells you, in coded findings, whether the wiring can stay, whether parts of it have to go, and whether the consumer unit has the capacity and the protection for what you are about to add. A house that only needs a partial rewire is planned very differently from one that needs the lot, and finding out on day three of the strip-out is the expensive way to learn it. Our guide to the signs a house needs rewiring covers what actually matters.
The order the work happens in.
A renovation runs in a fixed sequence and the electrics touch three points in it. Miss one and the next trade closes the door on you.
- Strip-out. Floors up, old plaster off, ceilings down where they are coming down. This is when cable routes are surveyed properly, because you can finally see the joists and the voids.
- First fix. Cables, back boxes and containment go in before the plasterboard and plaster. Every socket, switch, light position, data point, extractor fan and outdoor feed you will ever want in that wall has to be decided by now. This is the window the whole article is about.
- Second fix. After plastering and decorating, the faceplates, fittings and consumer unit are connected, then every circuit is tested and certified.
The gap between first fix and second fix is where plans quietly change. The kitchen designer moves the island, a wall light becomes two. Each change is a chase in fresh plaster and a return visit. Share one dated drawing between the builder, the kitchen supplier and the electrician, and issue any revision to all three at once.
The decisions that lock in at first fix.
- Where the consumer unit lives. Moving it later means moving every circuit in the house. If the existing position is in a cupboard you are about to remove, or somewhere you cannot reach, decide now.
- Spare capacity. A board with no spare ways cannot take a new circuit without being replaced, and the replacement is itself a job. Plan the board for the circuits you will want in ten years, not the ones you have today. Our guide to whether you need a new fuse board covers the honest triggers.
- The big loads. An electric shower, an induction hob, an oven on its own circuit, a heat pump, an EV charger, a hot tub. Each wants its own circuit and each pulls on the same incoming supply. Even if the heat pump or charger is a few years away, the cable route and the spare way cost very little while the floor is up.
- Bathrooms and kitchens. The wiring regulations treat bathrooms as special locations with zones that dictate what can go where, and both rooms carry the most circuits in the house. Shaver points, mirror lighting, underfloor heating, extractors and towel rails all need a feed that is easy now and awkward after tiling.
- Lighting as circuits, not just fittings. Decide which lights switch together, where you want two-way switching, and whether any room wants dimming or scene control. A switch position is a cable, and a cable is a first-fix decision.
- Data and everything else that needs a wire. A home office, a TV wall, a doorbell camera or a wired access point all work better on a cable, and a cable in the wall costs almost nothing at first fix. Leave a draw cord in any empty conduit.
- Outside. Garden sockets, lighting, a shed or office supply. The feed leaves the house through a wall you are about to render or a floor you are about to finish.
What is notifiable, and why it changes the timing.
In England, Part P of the Building Regulations means certain domestic electrical work must be notified to building control: adding a new circuit, replacing a consumer unit, and most work in a bathroom. A renovation of any size almost always includes at least one of those. If a registered electrician does the work, they certify and notify it themselves and you receive an Electrical Installation Certificate plus a Building Regulations compliance certificate. If the work is done by somebody who is not registered, building control has to be told before the work starts and inspects it, which adds time and cost. The certificates are what a buyer’s solicitor asks for when you sell.
If you are extending as well as renovating, the extension wiring guide covers the new-build side, and the guide to what an extension electrical quote should include shows how to turn the decisions on this page into a scope you can compare.
What the price is made of.
We do not publish figures because two houses of the same size can be days apart in labour. The price is built from the number of circuits and points, how much of the existing wiring the inspection says can stay, whether the consumer unit is being replaced, the length and difficulty of the cable routes, how many special locations are involved, the testing of every circuit at the end, and the certification and notification. A clear first-fix drawing shortens all of it, because the electrician is wiring a plan rather than working out the plan on site.
What you should have at the end.
An Electrical Installation Certificate for the new work, a Building Regulations compliance certificate for anything notifiable, the schedule of test results that sits behind the certificate, and a copy of the drawing showing what went where. Keep them with the house paperwork. If you let the property, the landlord electrical safety rules mean the next inspection is due within five years, and a clean set of certificates makes it a short one.
We plan and wire renovations across Buckinghamshire, Bedfordshire, Hertfordshire and Northamptonshire, and we are in Milton Keynes and Bedford most weeks. If you would like us to look at the plans before the builder starts, that is the cheapest visit of the whole project.
Sources: Approved Document P, Electrical safety: dwellings; IET: Part P, England and Wales; BS 7671, the IET Wiring Regulations; GOV.UK: Building regulations approval; The Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020.
Asked about this.
Should I rewire when renovating a house?
Only if an inspection says so. An EICR tests the existing circuits and tells you whether they can stay, need partial replacement or need a full rewire. Many renovated houses need a partial rewire plus a new consumer unit rather than the lot, and the report is what settles it. If a rewire is needed, a renovation is the cheapest time to do it because the floors and walls are already open.
At what stage does the electrician come in on a renovation?
Three times. Before the work starts, to inspect and help plan. At first fix, after strip-out and before plastering, to run cables and fit back boxes. And at second fix, after decorating, to fit the faceplates and fittings, connect the consumer unit and test and certify everything. The planning visit is the one people skip, and it is the one that saves the most.
How many sockets should each room have?
The wiring regulations do not set a number, so it is a design decision. Plan for how the room will actually be used, including the furniture positions, then add more than feels necessary, because a socket is cheap at first fix and expensive once the wall is plastered. Kitchens, living rooms and home offices are where people most often run short.
Do I need a certificate for electrical work during a renovation?
Yes. New circuits, a replacement consumer unit and most bathroom work are notifiable under Part P of the Building Regulations in England. A registered electrician issues an Electrical Installation Certificate and notifies building control for you, and you receive a compliance certificate. Keep both. They are asked for when the house is sold or let.