The short answer
Installing a consumer unit in a garage typically costs around £400–£900 in the UK, though the range is wide because the cable run from the house is often the dominant cost driver. A small 4-way or 6-way garage board for basic lighting and sockets might run £400–£600 in a simple, close-to-house installation; a larger sub-board for a workshop or EV charger, with a longer armoured cable run underground or overhead, can push to £700–£1,000 or above. The work is notifiable under Part P of the Building Regulations as a new circuit from the house, so it must be carried out by — or pre-notified through — a registered electrician, and should come with an Electrical Installation Certificate (EIC).
A garage consumer unit is a small sub-board fed from the main house consumer unit. The complexity — and therefore the cost — depends heavily on the distance and route of the supply cable and on what the garage needs to power.
Typical garage unit costs
- Small garage board (4–6 way)~£400–£600
- Larger sub-board / workshop (8–10 way)~£600–£1,000+
- Armoured cable (per metre, supply only)~£8–£20
- EIC and Part P notificationshould be included
- RegulationPart P notifiable outbuilding circuit
What drives garage consumer unit installation costs
The headline figure has several components, and the cable run is often more significant than the board itself:
- Cable run length and type: the supply from the house to the garage must be protected — typically armoured SWA (steel-wire armoured) cable buried underground or run overhead. A garage 5 metres from the house costs far less to cable than one at the far end of a long garden. Underground routes also need a trench, which adds time or plant hire.
- Board size and type: a simple garage for lighting and sockets needs a small 4-way or 6-way board; a workshop with power tools, heating and an EV charger needs a 6-way to 10-way unit with appropriate protection. An RCBO board costs more than a simpler RCD board.
- Earthing: a detached outbuilding must have its own earthing arrangement (typically a supplementary electrode), which adds to the installation.
- Isolation requirements: the feed from the house must include a means of isolation — usually a fused connection unit or a suitable breaker in the house consumer unit — which may be a new circuit or an existing spare way.
- EV charger readiness: if the board is being installed to accommodate an EV charger, the supply cable and isolation must be sized and rated for that load from the outset.
| Scenario | Typical cost | Notes |
|---|---|---|
| Basic 4-way board, attached/close garage | £350–£550 | Short cable run, lighting + sockets |
| 6-way sub-board, detached garage (<10m) | £500–£700 | Armoured cable underground |
| 8-way sub-board, detached garage (>15m) | £700–£1,000 | Longer cable run, possible trench |
| Workshop / EV-ready board, 10-way | £800–£1,200+ | Larger board, heavier supply cable |
| Trench excavation (if required) | £50–£150+ extra | Depends on length and ground condition |
Indicative UK figures for guidance. Sources: Checkatrade and MyJobQuote trade cost guides. Actual costs depend on site conditions and electrician's inspection.
Part P and certificates for garage work
Running a new circuit from the house to an outbuilding — including the garage consumer unit — is notifiable work under Part P of the Building Regulations in England and Wales. This means:
- The work must be carried out by a registered electrician (a member of a competent-person scheme such as NICEIC, NAPIT or SELECT) who self-certifies and notifies building control, or the work must be pre-notified to building control directly.
- You should receive an Electrical Installation Certificate (EIC) for the new installation.
- Without certification, the installation may not be covered by your home insurance, and you will likely have to account for the uncertified work when selling the property.
Scotland has slightly different arrangements under the Building (Scotland) Regulations; the same principle — that this is notifiable electrical work — applies, but the administering body differs.
Getting the supply sizing right first time
The most expensive mistake with a garage sub-board is undersizing the supply cable. An armoured cable buried underground is costly and disruptive to replace. Before the job is quoted, have a clear list of what you want the garage to power now and in the next five to ten years. If an EV charger is even a possibility, tell the electrician at the outset so the cable, the isolation and the board can be sized for that load from the start.
Similarly, if the house consumer unit is already full — no spare ways — the electrician may need to fit a larger board in the house as well, which changes the scope and cost of the overall job. A site visit and a clear scope before accepting any quote avoids surprises.
Frequently asked questions
Does a garage consumer unit need its own earth?
Yes. A detached outbuilding must have its own earth electrode (typically a rod or tape) because it is a separate structure from the house. The earthing arrangement must be confirmed as adequate during testing and documented on the EIC.
Can I use a small consumer unit or do I need a full board?
The board size depends entirely on what you want to power. A simple garage for a few sockets and lights can use a small 4-way or 6-way unit. A workshop with heavy tools, heating or an EV charger needs a properly sized board rated for those loads. Tell your electrician what you plan to run so the board is right first time.
Is garage wiring notifiable under Part P?
Yes. Running a new circuit from the house to an outbuilding is notifiable work under Part P of the Building Regulations in England and Wales. The installation must be carried out by a registered electrician who self-certifies, or pre-notified to building control. You should receive an EIC on completion.
Sources & further reading
- Checkatrade — cost of replacing a fuse box / consumer unit
- MyJobQuote — replace a fuse box cost guide
- gov.uk — Part P: electrical safety in dwellings (outbuildings)
Figures on this page are typical UK ranges drawn from published sources and depend on your specific property and installation. They are guidance, not a quotation.