Electrical vehicle charging

The Society of Motor Manufacturers & Traders (SMMT) has said that in 2021 more electric cars were registered in the UK than in the previous five years combined. As a result, demand for home-based charging infrastructure solutions is set to escalate, with consumers looking for an easy, safe, and convenient method to power up their vehicles from the comfort of their home.

To help electrical contractors who may be receiving increased requests to support customers, our Training and Technical Support Manager, Ian Wassell, answers the most frequently asked questions when it comes to amending a pre-installed consumer unit to safely incorporate an electric vehicle charging device.

How many mA should an RCD that is supplying a vehicle charger be rated at?

It clearly states that regulation 722.531.3 requires the RCD (Max 30mA) supplies the car charger installation.

If the car charger has an RCD-DD that will detect and disconnect any DC issues above 6mA, what type of RCD can be used?

It is recommended that a Type A RCD is used in this circumstance. This is because a Type A can still work correctly up to a level of 6mA DC. If over 6mA, the Type A device could be blinded and fail to work. The Type A RCD is the preferred option as Type A solutions are now commonplace and cost effective. As a result, most EV charger manufacturers have specified a 6mA RCD-DD that is already built in.

Why would you not connect a Type A RCD downstream of a Type AC RCD?

Any DC problem from the vehicle up to 6mA will not be disconnected by the car charging equipment and the Type A RCCB is not affected by DC up to 6mA. However, a Type AC fitted upstream in the consumer unit could be affected or even blinded by this DC. The RCCB fitted in the consumer unit supplies other circuits around the home which may no longer have residual current protection. Should anyone contact anything live on any of the circuits supplied from this device, it could lead to severe consequences.

Do you have to disconnect the neutral when supplying a vehicle charger with a 30mA RCD?

Regulation 722.531.3 requires that an RCD (Max 30mA) supplies the car charger. This RCD will disconnect all the live conductors, including the neutral. Therefore, the single module RCBO should not be used for this type of application.

Access our Electric Vehicle Charging training module through the Hager Online Academy. Covering all safety requirements and protection solutions, click here to get started.