A home EV charge point is a fixed charging unit for an electric car on your own property: a wall-mounted unit (wallbox) or a post, connected to the electrical installation on its own dedicated circuit. Unlike an ordinary socket outlet, a charge point is designed to deliver full power for hours on end, and it communicates with the vehicle about the permitted charging current.
An extension lead or a standard socket outlet is not an alternative: neither is designed for sustained loading, and both present a real fire risk.
Power and connection
| Supply | Power | Typical charging rate |
|---|---|---|
| Single phase, 16 A | About 3.7 kW | About 15-20 km per hour |
| Single phase, 32 A | About 7.4 kW | About 30-40 km per hour |
| Three phase, 16 A | About 11 kW | About 50-60 km per hour |
| Three phase, 32 A | About 22 kW | About 100-120 km per hour |
The charging rate is limited by the weakest link in the chain: the supply, the charge point and the car’s onboard charger. Many cars will not charge on AC faster than 7.4 or 11 kW, in which case a larger unit brings no benefit.
What the installation involves
- Assess the supply — is there room for an extra circuit in the consumer unit, and is the main fuse rating adequate?
- Dedicated circuit — the charge point gets its own circuit with its own protective device and residual current protection
- Residual current protection — charging can produce DC residual current. A type B RCD is required unless the charge point itself provides DC fault detection
- Earthing arrangement — on a PME supply an open PEN conductor is a recognised hazard, so either an earth electrode or a charge point with integral open-PEN detection is needed
- Cable route and groundwork — the cable size follows from the length and the current; a freestanding post means a trench with a duct
- Load management — this automatically reduces the charging power when the rest of the house is drawing heavily
Have the work done by a competent electrician to BS 7671, including Section 722 for electric vehicle supply equipment, and notified under the building regulations. For a straightforward installation including unit, labour and a dedicated circuit, a total in the order of 1,000 to 2,500 euros is realistic; groundwork, a long cable route or a supply upgrade come on top.
Related terms
- Consumer unit
- Circuit
- Residual current device
- Earthing
- Electrical installation
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