Can Your House Take a 7kW EV Charger? The Load Check Before You Order One

The short answer

Most Cornish houses take a 7.4 kW charger without any upgrade work. A 7.4 kW unit is a dedicated 32 A single-phase circuit, and a modern consumer unit on an 80 A or 100 A main fuse has room for it. The four things that change that answer are the size of your main fuse, the state of the consumer unit, the earthing arrangement, and what else in the house draws heavily at the same time.

None of them is exotic, and all four can be established before you buy anything. A quote given over the phone without any of them is a price, not an assessment.

What your main fuse is rated at

The main (service) fuse is the sealed cut-out where the supply enters the house, usually next to the meter. Domestic supplies are commonly 60, 80 or 100 A. A 32 A charger on a 100 A supply is comfortable; on an older 60 A supply alongside an electric shower, an immersion heater and an induction hob, the arithmetic gets tight on a winter evening.

Tight does not mean impossible. It means the design has to account for it — which is what load management, below, is for. What it must never mean is an installer quietly fitting the charger and hoping, because the failure mode is the main fuse blowing, and that is a supplier call-out, not something your electrician can reset.

Room in the consumer unit

A charger needs its own way with the correct protective device. If the consumer unit is full, or is an older board without the required protection, the options are a separate enclosure next to it or a board upgrade. Neither is dramatic, but they change the price, and they are the most common reason a fixed quote moves after a survey.

Earthing, PME and open-PEN

This is the technical point that matters most and gets explained least. Most UK supplies, including across Cornwall, use PME (protective multiple earthing). Vehicle charging outdoors introduces a specific risk if the supply's combined neutral-and-earth conductor fails, so Section 722 of BS 7671 requires that case to be dealt with. In practice that means either a chargepoint with integral open-PEN detection, which disconnects if it sees the fault signature, or a separate earth electrode installed to the required specification.

Nearly all current chargepoints include open-PEN protection, which is why this rarely adds cost — but it is a direct answer to the question of whether any electrician can fit one. They can, if they work to Section 722 and notify under Part P. The ones who do it weekly simply hit fewer surprises.

Load management

Load management (sometimes "load curtailment") monitors the whole-house current and throttles the charger when the rest of the house is drawing hard, then lets it return to full speed. It is the standard answer to a smaller main fuse, and it is invisible in practice: your car charges a little slower for twenty minutes while the shower runs.

It also matters for the overnight window. Since 2022 the Electric Vehicles (Smart Charge Points) Regulations have required new home and workplace chargepoints to have smart functionality, including default off-peak charging hours and a randomised start delay — so a compliant unit is already trying to charge when the grid and your tariff are cheapest.

Three-phase and 22kW chargers

A 22 kW charger needs a three-phase supply. Three-phase is uncommon in Cornish housing outside farms, converted commercial buildings and some newer developments, and a domestic single-phase supply is not upgraded on request — it is a DNO job with a cost and a timescale attached. Before accepting any quote that offers 22 kW at home, establish what supply the property actually has.

For most drivers it is academic anyway: at 3.5 miles per kWh, a 7.4 kW charger returns roughly 25 miles of range per hour, so a seven-hour off-peak window is around 175 miles. Very few households need to beat that at home.

What a survey actually looks at

Main fuse rating; consumer unit type, condition and spare ways; earthing arrangement; the cable route from board to parking space and its length; where the meter is; and whether anything else is about to be added — a heat pump, a hot tub, a second car. The last one catches people out: it is far cheaper to size for both at once than to come back.

If you want the models, prices and grant position first, see EV charger installation Cornwall. If you already have panels and want the car to use them, charging an EV from your own solar covers how diversion actually behaves.