Can you install an EV charger on a detached garage?

Most detached garages have some kind of supply, and most of those supplies were installed for a light, a socket and maybe a freezer. A 7.4kW charger draws 32A continuously, an entirely different proposition.

So the first job is establishing what's actually there:

• What size cable runs to the garage, and is it armoured or something less suitable buried in the ground?
• How is it protected back at the house, and how long is the run?
• Is there a board in the garage, or does everything come off one circuit?
• What else is out there that will be running at the same time?

Occasionally an existing supply is generous enough to take a charger as it stands. More often it isn't, and it's better to know that before you buy a unit.

Where a new run is needed, it's steel wire armoured cable, sized for the load and the distance, taken from the house consumer unit out to a small board in the garage.

• Buried at a sensible depth with warning tape above, or clipped along a wall or fence line where the route allows.
• Route agreed with you beforehand, and recorded, so nobody puts a spade through it in two years' time.
• A small consumer unit in the garage, so the building has its own protection and a fault out there doesn't take the house out.
• Reinstatement where the route crosses a lawn, border or driveway, worth being explicit about in the quote.

This is the part that makes a detached-garage job cost more than a wall-mounted one. It isn't difficult work; it's just more of it.

It's worth knowing this exists, because it occasionally changes the design. Most UK supplies are PME, where the earth and neutral are combined in the incoming supply. Extending that earthing arrangement out to a detached building, particularly one you can touch while standing on the ground outside, needs thought, and sometimes the right answer is a separate earth electrode for the outbuilding.

Your electrician should be establishing the earthing arrangement at survey stage. If nobody asks about it, that's a reasonable prompt for a second opinion.

Sometimes, yes, and it's worth asking. If the car parks on the drive in front of the garage rather than inside it, a charge point on the house wall may reach perfectly well and cost considerably less.

If the car genuinely lives in the garage, or the garage is the only sensible mounting position, the armoured run is the right answer, and while it's being done, it's the cheapest time you'll ever have to give that garage a proper supply for everything else too.