Guide
EV charger in a detached garage or on a long cable run
A charger in a detached garage or at the bottom of a garden may be possible, but the distance and route can add electrical work and cost. Ask an installer to assess the supply cable, protection, groundwork and any data connection. There is no single cable size that suits every home.
In plain English
Plan the whole route, not just the charger position
Walk the proposed route with the installer: from the home's electrical equipment, across the garden or driveway, through the garage wall and out to where the car parks. Note approximate distance, changes in level, paving, garden beds, gates and places where cars cross.
A short, clear route may be simpler than a shorter route blocked by paving, retaining walls or buried services. Do not dig to investigate or assume the route is clear. The installer should check permissions, access and how disturbed surfaces will be restored.
Think about how the charger will connect to its app or energy service. Wi-Fi may not reach a detached garage; some products have another connection option, while other smart features need a reliable signal. Ask what will work at the proposed location.
In plain English
Why a long cable run needs a proper design
Voltage drop is the reduction in voltage along a cable while electricity is flowing. In simple terms, a longer route can mean less voltage reaches the charger. The installer considers the distance alongside expected power, cable type, how it will be installed and the equipment protecting the circuit.
A cable inside a wall, buried in a duct, surrounded by other cables or run through a warm or shallow channel may need a different design. Existing supply capacity, earthing and protective devices also matter. There is no universal cable size for every detached garage.
Do not choose or buy a supply cable from an online sizing chart. Have a competent installer design and assess the actual route. The IET cable-channel information illustrates how installation conditions affect a design; its examples are not a specification for your garden.
In plain English
Ask what digging and reinstatement cost
Check whether the quote includes trenching, ducting, drilling, a post, reinstating paving or landscaping and disposing of spoil. A route across a driveway can involve different work from one beside a wall. Ask what the finished surface will look like and who is responsible if it later settles.
Other buried services may affect where a route can go. The installer must establish the safe method. If a route touches a public highway or pavement, stop and check permissions. For a crossing from a house to street parking, read the no-driveway guide.
In plain English
What photos and details help an installer quote?
Send safe photographs of the parking position, proposed charger location, visible consumer-unit and meter area, and the route between them. Include a rough distance, surface types, gates or shared land, and whether solar, a home battery or other large electrical loads are present.
Ask each installer to state the route, cable length, groundwork, making good, monitoring and electrical work included. Two quotes can differ because they allow for different routes or reinstatement; ask what could change the price after a survey. Never remove electrical covers or dig a test trench for a quotation.
Your next step
Before ordering a charger
Confirm the car's charging connector and AC limit, the lead length needed from the final charger position, and whether the charger's connectivity works in the garage. The supply cable from the house and the plug-in lead from wallbox to car are different parts of the installation.
Use the installation overview, the cable-size guide and the consumer-unit guide to prepare questions. The final design belongs to an installer assessing your property.
Further reading
Sources
- Last reviewed
- EV charging design considerations for pavement cable channels — Institution of Engineering and Technology, Wiring Matters, July 2026. Current-carrying capacity, temperature, voltage drop and route assessment. Example tables use specific cable and channel conditions.
- Electric vehicles: cost, time and what's involved — UK Power Networks. Supply assessment, installer notification and site-specific network work. UK Power Networks' process applies in its own service area; other operators have their own arrangements.
- Protective, isolation and switching devices explained — Institution of Engineering and Technology, Wiring Matters, July 2026. Dedicated Mode 3 charging circuits, different protective-device functions and the need for installation-specific selection. Not a universal consumer-unit or breaker specification.
- Electrical safety advice for electric vehicles — Electrical Safety First. Dedicated charging equipment, competent installation and stopping use of damaged charging cables.
- Multiple installations at the same property — UK Power Networks. Combined electricity demand, installer assessment and notification or supply work in this operator's area; checked 6 October 2026.