Detailed breakdown of garage electrical installation costs in the UK for 2026 — detached garage from £800, integral garage from £400, SWA armoured cable and trenching costs, garage consumer unit, EV charger add-ons, and Part P compliance.
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Written and reviewed by Andrew Moore, founder of Elec-Mate, against BS 7671:2018+A4:2026, IET Guidance Note 3 and the IET On-Site Guide.
The short answer
A detached garage electrical installation typically costs £800 to £2,000, and an integral garage £400 to £800. Rewiring an existing garage on a sound existing supply also runs £400 to £800. Trenching adds £15 to £25 per metre through a garden, or £30 to £60 through concrete.
The single biggest variable is the SWA cable run from the house and what it has to cross. Adding a 7 kW EV charger while the trench is open costs £200 to £400 rather than £600 to £1,200 as a separate job.
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01 · Cost Guide
| Job | Typical cost | What it covers |
|---|---|---|
| Detached garage, full install | £800 – £2,000 | SWA cable, trenching through garden, small consumer unit, lighting and socket circuits, testing and certification |
| Integral (attached) garage | £400 – £800 | Circuits fed from the main house consumer unit through the party wall. No external cable run, no trenching |
| Rewire an existing garage | £400 – £800 | New lighting and socket circuits on a sound existing supply, small board if needed, testing and certification |
| EV charger, added to the same job | £200 – £400 | Marginal cost of a 32 A circuit when the supply cable and board are being installed anyway. Charger unit not included |
| EV charger, standalone job | £600 – £1,200 | Circuit and installation as a separate visit. Charger unit not included |
| Trenching, per metre | £15 – £60 | £15 – £25 through lawn or soft ground, £30 – £60 through concrete |
Three things decide where in the range a garage job lands: whether the garage is attached or detached, how far the cable has to travel, and what it has to travel under. A 10-metre run across a lawn and a 25-metre run under a concrete driveway are the same electrical design and completely different jobs on the day.
In England and Wales, installing the new circuit that supplies a garage — and installing or replacing a consumer unit — is notifiable under Part P of the Building Regulations. An electrician registered with a competent person scheme self-certifies the work, so no separate building control application is needed.
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02 · Cost Guide
A detached garage installation means running an armoured cable from the main house consumer unit to the garage, usually underground. Cost scales almost entirely with the length and difficulty of that run.
| Cable run | Typical cost | Scope |
|---|---|---|
| Up to 10 m, through garden | £800 – £1,200 | Usually one day. 6mm² SWA, trench through lawn, small consumer unit, one lighting circuit, one socket circuit |
| 10 – 25 m, mixed surfaces | £1,200 – £1,600 | Longer run, likely trenching through a path or patio, higher materials cost |
| Over 25 m, or under a driveway | £1,600 – £2,000+ | Diamond cutting or boring through the slab, significant reinstatement, and possibly a larger cable to hold the voltage drop |
Beyond about 25 metres the cable stops being sized purely on current-carrying capacity and starts being sized on voltage drop. Section 525 of BS 7671 requires the voltage at fixed current-using equipment to stay within its product standard, and Regulation 525.202 deems that satisfied where the drop from the origin of the installation to the load point stays inside the figures in Appendix 4, Table 4Ab — 3 % for lighting and 5 % for other uses. Stepping from 6mm² to 10mm² to hold that figure adds material cost across the whole run, not just the extra metres.
03 · Cost Guide
An integral or attached garage shares a wall with the house, which removes the external cable run, the armoured cable and the trenching from the job entirely. Circuits are fed from the main house consumer unit through the party wall.
| Scope | Typical cost | What it covers |
|---|---|---|
| Lighting and sockets only | £400 – £600 | One lighting circuit, one socket circuit (ring final or radial), tested and certified. Assumes the existing board has spare ways |
| Plus consumer unit upgrade | £800 – £1,200 | New consumer unit in the house to Reg 421.1.201, plus all garage circuits |
| Plus EV charger | £1,000 – £1,800 | Dedicated 32 A EV circuit, board work if required, charger installation. Charger unit not included |
Inside an integral garage, standard 2.5mm² twin and earth is fine for the socket circuit provided it runs in a permitted zone or is mechanically protected. Because the run stays within the building structure, no armoured cable is needed.
Socket-outlets rated up to 32 A need additional protection by a 30 mA RCD under Regulation 411.3.3 — which in a garage matters, because that is exactly where extension leads and outdoor power tools get plugged in.
04 · Cost Guide
Regulation 522.8.10 is the one that decides the cable. A cable buried in the ground must incorporate an earthed armour or metal sheath — or both — suitable for use as a protective conductor, unless it is installed in a conduit or duct that provides equivalent protection against mechanical damage. For a domestic garage supply that means SWA in practice.
| Decision | What applies |
|---|---|
| Standard domestic supply | 6mm² SWA is the usual starting point for lighting, sockets and a small workshop. The final size must be confirmed against the Appendix 4 table for the reference method actually used — direct in the ground and in a duct in the ground are different columns — and against the protective device rating. |
| EV charger supply | A 7 kW charger draws around 32 A for long periods. On longer runs 10mm² SWA is commonly needed to keep the total voltage drop within the 5 % allowed for “other uses” in Appendix 4, Table 4Ab. |
| Burial depth | Reg 522.8.10 requires “a sufficient depth to avoid being damaged by any reasonably foreseeable disturbance of the ground” and gives no figure. The familiar 0.6 m comes from notes to the caravan park and marina sections (Regs 708.521.7.2 and 730.521.101.3.2) and is the working minimum the trade applies to garden runs. |
| Marking the route | Reg 522.8.10 requires the location of buried cables to be marked by cable covers or a suitable marker tape, and buried conduits and ducts to be suitably identified. Sand bedding above and below the cable is good practice rather than a BS 7671 requirement. |
| Overhead alternative | Where trenching is not viable, an insulated overhead run on a catenary is an option and is far cheaper than cutting a driveway. BS 7671 gives no general height for a domestic span; the benchmark installers work to is the 3.5 m — and 6 m where vehicles pass beneath — set for caravan parks and marinas in Regs 708.521.7.3 and 730.521.101.3.3. |
05 · Cost Guide
Once a garage has more than one final circuit it needs a distribution board of its own. Regulation 314.4 requires each final circuit to be connected to a separate way in a distribution board, and Regulation 462.2 requires every circuit to have a means of isolation for all live conductors. A small board where the supply enters the garage satisfies both and keeps a fault in the garage off the house board.
| Board | Fitted cost | Suits |
|---|---|---|
| Small, 4 way | £300 – £450 | One lighting circuit, one socket circuit, one or two spares. RCBOs or dual RCD |
| Larger, 6 – 8 way | £400 – £600 | Adds an EV charger circuit, a workshop power circuit, outdoor sockets and security lighting |
| Lockable isolator | Add £40 – £90 | Reg 462.3 lists padlocking and lockable enclosures as ways of preventing inadvertent re-closure. Worth it where the garage is shared or let |
What BS 7671:2018+A4:2026 asks for
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06 · Cost Guide
If the garage is being wired anyway, adding an EV charger circuit costs a fraction of what the same charger costs as a standalone visit. The supply cable, the trench and the consumer unit are the expensive parts, and they are already paid for.
| Route | Cost | Notes |
|---|---|---|
| Added to the garage job | £200 – £400 | 7 kW / 32 A circuit only. Cable and board already covered by the main job |
| Standalone installation | £600 – £1,200 | Separate visit, separate cable route and board work |
| Charger unit itself | £500 – £900 | Typical range for a smart charger. Not included in either figure above |
A 7 kW charger needs a dedicated 32 A circuit and draws close to that continuously, so the supply SWA has to be sized for the load with the correction factors that apply to its actual reference method — depth of burial, grouping with other circuits and any thermal insulation. On runs over roughly 20 metres, 10mm² SWA is commonly what the voltage drop calculation lands on. Full detail is in the EV charger installation cost guide.
On grants: the domestic Electric Vehicle Homecharge Scheme closed to most homeowners in 2022. The remaining chargepoint grants are aimed at flat owner-occupiers, renters, landlords and workplaces, and are administered by the Office for Zero Emission Vehicles (OZEV). Check current eligibility on GOV.UK before you promise a customer a contribution — the schemes and the amounts change.
07 · Cost Guide
In England and Wales, installing a new circuit to supply a garage, and installing or replacing a consumer unit, is notifiable work under Part P of the Building Regulations. That applies whether the garage is detached or integral. Minor work on an existing circuit outside a special location is generally not notifiable. Scotland and Northern Ireland operate their own building standards regimes.
| Document | What it is and why it matters |
|---|---|
| Electrical Installation Certificate | The EIC records the design, construction, inspection and test results, and is required by Reg 644.1. It is the compliance evidence solicitors routinely ask for on garage and outbuilding work when a property is sold. |
| Building Regulations Compliance Certificate | Issued when an electrician registered with a competent person scheme such as NICEIC or NAPIT self-certifies the work and notifies building control on your behalf. Without a registered electrician, the alternative is a building control application before the work starts. |
| EV chargepoint notification | The new circuit is notifiable under Part P in the usual way. Separately, a new chargepoint is normally notified to the distribution network operator; most EV installers handle that as part of the job. |
08 · Cost Guide
Garage installations are good bread-and-butter work. The scope is well defined, the design is routine, and an EV charger is an easy upsell once the supply cable and board are already on the quote.
Never quote a detached garage from the doorstep. Measure the route, note every surface it crosses, and find out what is already under the driveway. Quote the trenching as its own line item so the customer can see what the ground is costing them, and so a change of route does not eat your margin.
If the customer has a car, put the charger on the quote as a priced option rather than mentioning it. Adding a 32 A circuit while the trench is open costs a few hundred pounds; coming back for it later costs four figures. Showing both figures side by side is what closes it — the quoting app will produce the with-and-without version for you.
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Create itemised garage electrical quotes with armoured cable, trenching, consumer unit, and EV charger options. Issue EICs on site.
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