Charging an electric car from a three-pin socket on an extension lead is a stopgap, not a plan. Drawing around 2.3 kW for many hours puts a continuous load on a socket and wiring that were never designed for it, and domestic sockets have started fires when abused this way. A purpose-built home charger, wired on its own circuit, is faster, safer and in most cases cheaper per mile. This guide explains what the installation involves, what the Smart Charge Points Regulations require of the unit you buy, where grants still exist, and what you can reasonably do yourself.

How much power do you need?

Home chargers are almost always single-phase and rated at up to 7.4 kW, which is a 32 A supply at 230 V. Three-phase supplies allow higher figures but most UK houses have single-phase. The arithmetic for charging time is simple:

Charging time (hours) = energy needed (kWh) ÷ charging power (kW)

As an example with assumed figures, adding 40 kWh to a battery at 7.4 kW takes 40 ÷ 7.4 ≈ 5.4 hours, ignoring the tapering that happens near full charge and the losses in the charger and car, which typically add several per cent. At a 3.6 kW rating (16 A) the same top-up takes about 11 hours. Many cars cannot accept the full 7.4 kW on alternating current anyway; check your vehicle’s onboard charger rating. For most drivers who cover under 40 miles a day, even a 3.6 kW unit refills the car overnight, but 7 kW gives flexibility.

The dedicated circuit

An EV charger needs its own circuit from the consumer unit, with its own overcurrent protection. For a 32 A charger, typical practice is a 40 A protective device and a cable sized for the run length, installation method and ambient temperature. A commonly used cable is 6 mm² two-core and earth (T&E) for short, clipped-direct runs, stepping up to 10 mm² for longer runs or if the cable is buried in insulation or the voltage drop is too high. These are examples of common practice, not a design: the installer must calculate the cable size for your specific route under BS 7671. Our EV charger circuit and breaker calculator and the BS 7671 cable size calculator show how load, length and method affect the result.

Charging is a continuous load, so the circuit can run at its rated current for hours. That is why the cable and protective device are chosen with a margin and why the consumer unit must have capacity. Before ordering, the installer should check:

  • The existing consumer unit has a free way and is in good condition. Many older units need replacing, which is itself notifiable work.
  • The incoming supply can carry the extra load. In a house with electric heating, a heat pump or an immersion heater, simultaneous demand can approach the supply limit. Many installers apply a maximum demand assessment, and some chargers offer load-balancing with a clamp on the incoming meter tail to reduce the charge rate automatically when other loads are high.
  • The earthing arrangement of the supply, discussed next.

Earthing: PME and open-PEN protection

Most UK homes have a TN-C-S, or protective multiple earthing (PME), supply. In this arrangement a fault on the supply neutral can lift the earth of the whole installation to a dangerous voltage. For a car parked outside on wet ground, that is a real shock risk: someone standing barefoot on the ground touching the car body could receive a dangerous current. BS 7671 therefore does not allow an EV charger to rely on a PME earth unless extra protection is provided. The common solutions are:

  1. A charger with built-in open-PEN detection, which disconnects if the supply voltage goes out of tolerance, so that no dangerous voltage can appear on the vehicle.
  2. A separate earth electrode (an earth rod) that creates a local TT earth for the charger, with RCD protection.
  3. Supply from a TT installation if the property has one.

Which is cheaper depends on the site. Soil conditions can make an earth rod hard to achieve a low enough resistance, while chargers with built-in protection are widely available. Your installer should explain which they are using and why.

RCD protection and DC fault detection

EV chargers can leak small direct currents in a fault, which can blind a standard Type AC RCD. BS 7671 requires either a Type B RCD or an RCD of Type A with additional 6 mA DC fault detection, which many chargers include as standard. The circuit also needs a 30 mA RCD. Check the charger’s documentation to see what is built in, and make sure the installer does not duplicate protection unnecessarily or leave a gap.

Tethered or untethered?

A tethered charger has a fixed cable attached; an untethered one has a socket (usually Type 2) and uses your own cable. Tethered units are convenient and are always connected; untethered units look tidier when idle, protect the cable from weather and suit homes with two different cars. Either works. The choice is mostly aesthetic and practical.

The Smart Charge Points Regulations 2021

The Electric Vehicles (Smart Charge Points) Regulations 2021 apply to most home and workplace charge points sold in Great Britain from 30 June 2022. They are made under the Automated and Electric Vehicles Act 2018 and cover Great Britain; Northern Ireland has its own arrangements. The core requirements for the charger you buy include:

  • It must be capable of sending and receiving information over a communications network, and of responding to signals to adjust charging.
  • It must include pre-set default charging hours that fall outside peak hours. The regulations define peak hours as 8am to 11am and 4pm to 10pm on weekdays. The owner must be able to accept, change or remove the default hours at first use, and the charger must let the user override the default and charge immediately.
  • It must have a randomised delay feature, to stop millions of chargers all switching on at the same instant at the start of an off-peak window. (This requirement is described in the Regulations’ guidance; check the instructions of your specific model.)
  • It must meet security and tamper-protection requirements and measuring-device standards.
  • Manufacturers must provide a statement of compliance.

These obligations are on the manufacturer and seller of the charger, not on you. In practice they mean any new charger you buy should be “smart”, but you retain the ability to override scheduled charging. Installers should help you set the schedule so that your car is ready when you need it, and ideally align it with a time-of-use electricity tariff.

Do you need planning permission?

In England, installing a wall-mounted charger on a house or a free-standing charge point in the garden or driveway is often permitted development, provided limits on size, siting and height are met and the property is not a listed building or in a few restricted situations. Different limits apply to flats and to land in conservation areas, and Scotland, Wales and Northern Ireland have their own rules. Check the Planning Portal or ask the local planning authority before installing something that sits close to a highway or in a designated area. If you plan to dig a trench across a shared drive or pavement, you may need consent from the owner or highway authority.

Building regulations and Part P

A new EV circuit is notifiable electrical work in England. A registered installer certifying through a Competent Person Scheme will notify building control and issue an Electrical Installation Certificate and a compliance certificate. Our Part P guide explains the options if you are not using a registered installer. Do not attempt connection yourself unless you are qualified: the earthing and protection requirements above are not simple.

New dwellings in England must be built with EV charge point infrastructure under Approved Document S (in force since June 2022), which is why new-build homes often come with a ready-made cable route and a charge point. This does not apply to existing homes.

Grants and costs

The government’s chargepoint grants have changed over time. The earlier general home charger grant for houses ended in 2022. As of 2026, the GOV.UK electric vehicle chargepoint grants cover flat owners, renters, landlords and some others, with a grant of up to £500 per socket from 1 April 2026 reported for those groups, running to 31 March 2027. Because the details differ by group (and have been revised more than once), read the current GOV.UK page and use only an installer approved under the scheme. Homeowners with their own off-street parking in a house should assume there is no grant. Typical charger and installation prices vary widely with cable run, consumer unit work and whether any groundwork is required; get several quotes and ask what is included, such as the cable run length, any consumer unit upgrade and the certificate.

Check the electricity tariff, too. Some suppliers offer cheaper overnight rates for EV drivers, and a smart charger can use them automatically. If you have solar panels, some chargers can adjust to surplus generation, though not every model supports it.

A step-by-step sequence

  1. Decide where the car parks and measure the cable route to the consumer unit.
  2. Check your car’s maximum AC charging rate.
  3. Ask for a survey and a written quote that states the circuit design, protective devices, earthing method and certificates.
  4. Choose a charger that meets the Smart Charge Points Regulations and has the protections you need.
  5. Have the work done by a registered installer, who tests and certifies it.
  6. Set up the schedule in the app and file the certificate with your property documents.

This is general information, not electrical advice. Wiring regulations, grants and planning rules change, so confirm the current position with a registered installer and official sources.

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