Electrical Work During a Renovation | Horsham Builder’s Guide

Electrical work is one of those elements of a renovation that people tend to think about too late. The focus at the start of a project is usually on the exciting decisions — the kitchen layout, the bathroom tiles, whether to knock through to create open-plan living. The electrics get treated as something that will sort itself out along the way. Then halfway through the build, the walls are open, the plasterer is booked for next week, and suddenly everyone realises that nobody has properly planned where the sockets go, how many circuits are needed, or whether the existing consumer unit can handle the additional load.

Getting the electrical work right during a renovation isn’t complicated, but it does require planning, coordination, and the right conversations at the right time. This guide explains how the electrical side of a renovation fits into the wider project, when decisions need to be made, what to budget for, and how to avoid the mistakes that cost time and money to fix.

Why Electrics Need Planning Early

Electrical work during a renovation happens in two distinct phases — first fix and second fix — and both need to be programmed into the build schedule at specific points. Miss these windows and you’re either holding up other trades or paying to redo work that’s already been completed.

First fix is the rough-in stage. This is when cables are run through the walls, floors, and ceilings to the positions where sockets, switches, light fittings, and fixed appliances will eventually be installed. The cables are left with bare ends poking out of the wall, ready to be connected later. First fix has to happen after any structural work and before the plasterer arrives. Once the walls are plastered, running cables means chasing into fresh plaster and then patching it — additional cost, additional time, and a worse finish.

Second fix happens after plastering, painting, and often after flooring is down. This is when the electrician returns to fit the faceplates on sockets and switches, hang light fittings, connect appliances, and carry out all testing and certification. Second fix needs to be coordinated with the decorator and the kitchen or bathroom fitter to ensure everything happens in the right sequence.

The reason electrics need planning early is that first fix decisions are locked in once the plasterer finishes. Moving a socket from one wall to another before plastering is a ten-minute job. Moving it afterwards means cutting into a freshly plastered wall, rerouting the cable, replastering, redecorating, and wasting everyone’s time. The further into the project you leave electrical decisions, the more expensive changes become.

What Electrical Work Does a Renovation Typically Need?

The scope of electrical work depends entirely on what you’re doing to the property, but most renovations across Horsham involve some or all of the following.

Additional sockets are almost universal. Older properties were built with far fewer sockets than modern life demands. A 1960s house might have two double sockets in the living room and one in each bedroom. A modern renovation typically adds sockets for media equipment, bedside lamps, home office setups, kitchen appliances, and charging points throughout. Planning socket positions carefully at the start avoids the unsightly extension leads and adapters that plague under-provisioned homes.

New lighting circuits are common, particularly when the layout changes. If you’re knocking through rooms to create open-plan living, the original lighting plan no longer works. Recessed downlights, pendant lights over dining tables and kitchen islands, under-cabinet kitchen lighting, and dimmer switches all need planning during first fix. Lighting has a huge impact on how a room feels, and getting it right during the renovation rather than retrofitting later is both cheaper and better.

Dedicated circuits for high-demand appliances are a requirement in modern kitchens. Electric ovens, induction hobs, dishwashers, and washing machines each need their own circuit with appropriate protection. If you’re installing a new kitchen as part of your renovation, the electrician needs to know the appliance layout before first fix so the correct circuits are run to the right positions.

Consumer unit upgrades are frequently needed during renovations, particularly in older Horsham properties. If the existing consumer unit is full, outdated, or lacks RCD protection, the renovation is the ideal time to upgrade it. Adding circuits to a board that’s already at capacity isn’t possible without either upgrading the unit or fitting a supplementary board. Doing this during the renovation, when walls are already open and trades are on site, is far more cost-effective than doing it as a standalone job later.

Rewiring, either partial or full, is sometimes necessary. If your renovation involves opening up walls and the existing cabling is old, deteriorated, or doesn’t meet current standards, replacing it while access is available makes obvious sense. Running new cables through open walls is straightforward. Running them through finished walls is expensive and disruptive. A renovation is often the best opportunity you’ll get to upgrade the wiring without paying for the access separately.

Outdoor electrics are worth considering during a renovation if you have any plans for garden lighting, external sockets, a garden room, or an EV charger in the near future. Running a cable from the consumer unit to an external point while the house is being renovated is cheap and easy. Doing it as a separate project later means lifting floorboards, drilling through walls, and making good — all of which cost more than doing it at the right time.

When Should You Involve the Electrician?

The electrician needs to be involved far earlier than most people think. Ideally, they should visit the property during the planning stage, before any building work starts. This initial visit allows them to assess the existing installation, identify what needs upgrading or replacing, and advise on circuit requirements based on your plans.

For a kitchen renovation, the electrician needs to see the kitchen design — not just the room layout but the specific positions of appliances, the worktop lighting plan, and where sockets will be needed. A kitchen designer or builder can provide this, but the electrician needs it before first fix begins.

For a bathroom renovation, the electrician needs to know the lighting plan, the position of any electric shower or heated towel rail, the extractor fan location, and whether underfloor heating is being installed. Bathrooms are special locations under the wiring regulations, with specific rules about what can be installed in different zones relative to water sources. Getting this right from the start avoids compliance issues later.

For whole-house renovations, the electrician should walk through the entire property and discuss room by room what’s needed. This is the time to think about the mundane stuff that makes a huge difference to daily life — where you’ll charge your phone at night, where the hoover plugs in on the landing, whether you want a socket inside the cupboard under the stairs, and whether the TV position needs a media plate with power, aerial, and data connections behind it.

The key point is that involving the electrician after the build has started limits your options and increases costs. Involving them during the planning stage gives you the best outcome at the lowest price.

What Should You Budget for Electrical Work?

Electrical costs vary with the scope of the renovation, but here are realistic ranges for common scenarios across Horsham.

A single-room renovation with additional sockets, new lighting, and a switch upgrade typically costs between £500 and £1,200 for the electrical element. A kitchen renovation with dedicated appliance circuits, under-cabinet lighting, new sockets, and possibly a consumer unit upgrade usually falls between £1,000 and £2,500. A full bathroom electrical package including downlights, extractor fan, heated towel rail connection, and potentially underfloor heating connection costs between £500 and £1,500.

A whole-house renovation with new lighting throughout, additional sockets in every room, dedicated kitchen circuits, bathroom electrics, a consumer unit upgrade, and outdoor provision typically costs between £3,000 and £7,000. If a full rewire is needed on top of this, add another £3,000 to £6,000 depending on the size of the property.

These figures cover labour and materials for the electrical work only. They don’t include light fittings, appliances, or the decorative faceplates for sockets and switches, which are usually chosen by the homeowner and supplied separately.

Common Mistakes to Avoid

The most expensive mistakes in renovation electrics almost always come down to poor planning or late decisions.

Not planning socket positions properly is the most common regret. People renovate their entire house and then discover they don’t have a socket where they need one for the bedside lamp, the home office desk, or the kitchen worktop. Spend time during the planning stage walking through each room and thinking about how you’ll actually use the space. Mark socket positions on the walls with masking tape before first fix and live with them for a few days to check they feel right.

Choosing light fittings too late causes problems because different fittings have different fixing, wiring, and spacing requirements. A flush-mounted downlight needs a different ceiling cut-out and wiring arrangement from a pendant on a hook. If the electrician doesn’t know what fittings you’re using before first fix, they have to make assumptions that may not match what you eventually choose.

Underestimating the consumer unit situation catches people out. If your existing board doesn’t have spare capacity for additional circuits, the electrician can’t simply add more. A consumer unit upgrade needs to be factored into the budget and programme from the start, not discovered as an unwelcome surprise during first fix.

Forgetting about future needs is a missed opportunity. A renovation gives you access to walls, floors, and ceilings that are normally sealed up and inaccessible. If there’s any possibility you’ll want an EV charger, a garden room supply, additional outdoor lighting, or a home office setup in the next five to ten years, running the cables now while access is open costs a fraction of what it would cost to retrofit later.

Getting the Electrical Work Right

The single most important thing you can do is bring the electrician into the conversation early and make your decisions before the build starts. A good electrician working alongside your builder ensures the electrical work is programmed into the renovation at the right points, coordinated with other trades, and completed without delays or compromises.

If you’re planning a renovation at your Horsham property, get in touch. We coordinate all trades including electrics from day one, ensuring your project runs smoothly and the finished result works exactly the way you need it to.