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DO YOU REALLY NEED A TYPE B RCD?

The short answer is YES?

A Residual Current Device (RCD) is a device intended to detect dangerous residual currents and thereby mitigate the risk of electric shock or fire. In the case of EV charging, there is a risk of AC and DC residual currents, and it is vitally important that the RCD technology used has the ability to detect AC and DC residual currents.

You may think if you buy a charge point with a Type B RCD already fitted that your installation will not require one at the charge point main electrical box but chances are your electrician will want to fit one as it is more important to cut the power upstream in case of accidental cable damage.


Type B RCD´s are much more expensive than Type A but the reason they are recommended is that the charging circuitry in the power electronics of a modern EV has the potential to introduce harmonics or ‘smooth DC residual currents’ while charging. This DC residual current could potentially ‘blind’ a Type A RCD, rendering it incapable of responding to a situation in which there is a genuine electric shock risk.

A Type B RCD on the other hand provides a more comprehensive detection capability for various residual fault currents, including smooth DC currents.



At Teison we highly recommend that you make sure your electrician fits a Type BRCD on your charge point installation.

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