EV charger installation, supplied and fitted on its own circuit.

What a home charger installation costs

The standard price is for a 7 kW smart charger on a dedicated circuit run up to 15 m from the board, fitted where no digging is needed.

A longer cable run puts the price up, and so does a trench across a drive or a lawn. If the board has no room for another circuit, a new consumer unit may have to go in first. Anything beyond the standard job is priced on the written quote before you decide.

Siting the charger and checking the supply

The charger has to sit where the charging lead reaches the car's port without stretching across a path, and clear of a bumper as the car pulls in. We agree the spot at the survey.

From the charger, the cable runs to the board along an outside wall, fixed where it won't get knocked, or under a floor and through the loft. The power goes off for a short while when it is connected at the board.

A charger working flat out draws nearly as much as an electric shower and keeps going for hours, while the network operator's main fuse limits what the whole house can take at once. Building regulations guidance says new work should only go on once the existing equipment can carry the extra load, including the meter and the network's cable into the house. I look at the main fuse rating and the meter first, and if the supply needs upgrading, the network operator does that work.

Where the supply is tight, some chargers can measure what everything else in the house is using and slow their charging to stay inside the limit.

At the board, the circuit needs an RCD of a suitable kind. A fault in the car or the charger can leak direct current, which can stop an ordinary RCD working, so the protection has to cope with that unless the charger has it built in.

Why home chargers have to be smart

Under the Electric Vehicles (Smart Charge Points) Regulations 2021, a charger sold for a home in Great Britain has to be a smart charger. It must be able to change when and how fast it charges in response to a signal, and keep charging if it loses its internet connection.

Out of the box it is set to charge outside the busiest hours, and you can change or remove that setting when you first use it. It also has a randomised delay, so the chargers in a street don't all start at the same moment, and it has to meet a security standard.

Earthing and PEN-fault protection

Many houses take their earth from the supply cable, an arrangement called PME, where one conductor in the cable serves as both neutral and earth. If that conductor breaks, metalwork connected to the house earth can rise to a dangerous voltage.

Outdoors the risk is greater, because whoever touches the car is standing on the ground. So the wiring regulations only allow a PME earth for an outdoor charge point with an extra measure in place, either an earth electrode or a device that disconnects the car when that fault happens. Some chargers have the device built in.

Which measure suits a house depends on its earthing and where the charger goes. Whichever it is, PEN-fault protection is in the standard price.

Charging without a rewire

A charger doesn't usually mean rewiring the house. It's fed by a new circuit from the consumer unit, leaving the existing wiring as it is. That circuit is sized to carry the full charging current for hours at a time, which is why a charger is never taken off a socket circuit.

Wiring behind the board that hasn't been tested in years is worth a condition report before anything new is added to it.

Choosing the charger

A 7 kW smart charger is the usual size for a house on a single-phase supply, and it's what the standard job uses. Chargers come tethered, with a cable fixed to the unit, or untethered, with a socket for the car's own cable, which then lives in the boot.

Some chargers can top the car up from solar panels while they are generating. Fitting the panels is a different job, covered under solar and battery installations.

Building regulations for a home charger

Adding a circuit for a charger is notifiable building work in England, the same as any new circuit in a home. Part S, the part of the Building Regulations written for charge points, is for new and converted homes and for major renovations, so a charger added to a house that is already lived in falls outside it.

I test the circuit and the charger before handing over, and you get an Electrical Installation Certificate with the results.