Earthing

The Institution for Engineering and Technology (IET) sets guidance on electrical circuits in the UK, and has paid increasing attention to electric vehicle charging over recent years. Without delving too deep into the electrical details, this page highlights two recommendations: maintaining earthing exclusion zones around chargepoints, and including O-PEN fault protection devices.

Earthing exclusion zones

Chargepoints and their circuits must be at least 2.5m from other circuits on different earthing systems. This is to prevent risk of simultaneous earthing.

The 2.5m should be measured from the potential position of charging cars, which may be a considerable distance from the chargepoint itself.

This means that chargepoints should not be installed too close to lampposts, unless they are on the same earthing system.

It also has considerable implications for pavement channels. The government's Electric Vehicle Chargepoint Grant for Households with On-Street Parking has safety requirements that explicitly say: Electrical equipment of different systems must be at least 2.5 metres apart, for example a charging vehicle and another charging vehicle, or a charging vehicle and metalwork that is connected to a different earth system, such as a streetlight. This may mean two neighbouring houses are unable to both install cross-pavement solutions, or a cross-pavement solution cannot be installed near metalwork.

The above guidance is aimed at chargepoint installers, but some authorities are more cautious than others when it comes to eligibility for pavement channels and proximity to lighting columns or existing pavement channels.

O-PEN fault protection devices

O-PEN fault protection devices limit the damage that may be done if a certain conductor goes open circuit. In 2024, the IET published a standard for such devices.

The vast majority of home chargers and public chargers now contain an O-PEN fault protection device such as matt-e.

Some people think that O-PEN fault protection devices mean that the risk of simultaneous earthing is reduced so much that it should be possible to do away with earthing exclusion zones. This would mean it would be possible to have pavement channels in next-door houses.

For more details, see the IET's Code of Practice for Electric Vehicle Charging Equipment Installation and Regulation 411.3.1.1 of BS 7671, the IET Wiring Regulations.