Planning ElectricsFor a Home Extension or Renovation

A home extension, loft conversion, or major renovation is a significant investment — and the electrical work is one of the most important elements to get right. Poor planning or substandard installation at this stage is expensive and disruptive to fix later. This guide explains what to think about, when to involve an electrician, and how to make sure the work is done correctly and certified.

Involve Your Electrician Early

The biggest mistake homeowners make with extension electrics is treating them as an afterthought. Involving an electrician at the planning stage — ideally before the builder has started — allows them to advise on cable routes, consumer unit capacity, lighting layouts, and socket positions before walls go up and floors go down. Making changes after first fix is done is expensive and often means lifting finished floors or disturbing newly plastered walls.

A good electrician will also identify whether your current consumer unit has the capacity to take the new circuits required, or whether an upgrade is needed as part of the project. Better to find this out at the beginning than halfway through.

What Electrical Work Typically Happens in an Extension?

The scope of electrical work in a typical single or double-storey extension usually includes:

• First fix — running cable to all socket, lighting, switch, and appliance positions before the walls are boarded or plastered. This is the stage to run cables for anything you might want in the future, even if you don't connect it immediately.
• Connecting to the consumer unit — new circuits for the extension are run back to the main board and connected, ensuring the board has capacity and the correct protective devices.
• Second fix — once the plastering is done and decorating is underway, sockets, switches, and light fittings are fitted and connected.
• Testing and certification — all new work is tested to BS 7671 wiring regulations and an Electrical Installation Certificate (EIC) is issued on completion.

Loft Conversions

Loft conversions have their own specific electrical considerations. Access for cable runs can be more challenging, and it's worth thinking carefully about what you'll be using the space for — a bedroom will have different requirements to a home office or playroom.

Key considerations for loft conversions include:

• Adequate socket positions for the intended use, plus additional circuits for future flexibility.
• Recessed LED lighting — particularly useful in lofts where headroom is limited and protruding fittings would be impractical.
• Data and Wi-Fi points if the space will be used as a home office — wireless signal can be poor at the top of a house, so a wired network point is often the most reliable solution. See our Data & Wi-Fi installation service.
• Smoke detection — building regulations require interlinked smoke alarms in loft conversions. This is typically hardwired rather than battery-operated.

Kitchen Renovations

A kitchen renovation almost always requires significant electrical work, particularly if the layout is changing. Kitchens have specific regulations — including requirements for RCD protection on all circuits and restrictions on socket positions near sinks and hobs.

Common electrical work in a kitchen renovation includes:

• Dedicated circuits for the cooker, oven, and hob (these must be on their own circuit and correctly rated for the appliance).
• Circuits for integrated appliances — fridge-freezer, dishwasher, washing machine, tumble dryer — each ideally on a dedicated circuit with a local isolation point.
• Socket positions — review these carefully before committing to a layout. Too few sockets leads to extension leads and a cluttered worktop.
• Under-cabinet lighting and recessed downlights for the main illumination.
• Extractor fan wiring if not already in place.

Garage Conversions and Garden Rooms

Garage conversions and garden rooms are increasingly popular and both require a proper dedicated circuit run from the main house, not just an extension lead from the nearest socket. For a garden room used as a home office or gym, you'll typically want:

• A dedicated circuit with its own RCD protection at the consumer unit.
• An armoured cable run from the house — either underground or overhead — to the building.
• A sub-distribution board in the outbuilding to supply sockets, lighting, and any heating.
• Data cabling if the building will be used for work.

Building Regulations and Certification

All new electrical work in extensions, conversions, and renovations is notifiable under Part P of the Building Regulations. This means it must either be carried out by a registered competent person (such as a NICEIC Domestic Installer) who can self-certify, or inspected by Building Control after completion.

Using a registered electrician like Upton's means the certification is handled as part of the job — you'll receive an Electrical Installation Certificate on completion, which you'll need when selling the property. Uncertified work can cause significant problems at the point of sale and may affect your home insurance.

How to Plan Socket and Lighting Positions

Before first fix, think carefully about how you'll actually use each room. Walk through the space and consider:

• Where will the furniture go? Avoid sockets being hidden behind wardrobes or beds.
• Where will you want lamps, TVs, computers, or charging stations?
• Do you want any USB charging sockets built into the walls?
• Do you want outdoor sockets for garden equipment or a hot tub?
• Would you benefit from a dimmer switch in any rooms?

It costs very little extra to add additional socket positions or cable runs at first fix stage. Doing it later, once the walls are finished, is considerably more disruptive and expensive.