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is DC residual current protection required ?


I have a question regarding the use RCD type Bs and residual current detectors.

From what i have read online, it seems that EVSE stations require some sort of protection against DC fault currents. This can either be implemented with a type B rcd or a circuit that detects DC currents of 6mA or higher. From what i have read this requirement is stated in the IEC 61851 standard.

Could an expert on this topic perhaps help me clarify if this is also a requirement for single phase AC chargers or just 3 phase AC chargers? Is this an international requirement or just in the EU? I do not have access to these standards and would rather get an answer from someone with experiance on this topic anyways.

Thank you for your time.

DC residual current protection is required in the EU for both single and 3 phase.

Does OpenEVSE Hardware support RCD Type B?

No, the built-in GFCI in the regular build of OpenEVSE does not do DC fault detection, it only detects AC faults, so installed in the EU and other harmonized territories like the UK WILL require an external type B RCD.

note: External DC RCD protection is also required in the UK.
a good resource is run by the Openenergymon UK/EU resellers:

Recent UK wiring regulations now require installations to include protection against a PEN loss protection, for when an TN-type protective earth somehow becomes disconnected from the N conductor. That means either fitting a dedicated earth rod or a unit that monitors voltage levels and will disconnect all conductors if it is detecting over-voltage or under-voltage events that imply the protective earth is faulty. Your country's local wiring regulations may, or may not, also include such a requirement, and it depends on your property's particular electrical installation as to what earthing type is used.

I've always found this a weird requirement, you can use the granny chargers in regular household plugs without DC fault detection and then suddenly if its an evse you should use DC fault detection while its the same internal logic. So i've personally connected the evse to a 32amp socket (the blue ones), i'm not claiming you should do this or that you will get through a checkup, but at least i can just unplug the evse.

The comments above suggest that an external RCD Type B is required to be installed with an Open EVSE.
In New Zealand, manby of the EVSE being installed have DC filtering built into their EVSE and an external RCD Tyupe B is not required.  Is there any clarity from OpenEVSE around the capability of their EVSE.  We have enquired through their support team, but have not received a response.  Regards Howard Lewis AB Electrical (

It does seem crazy.  With a PEN fault, if the EV charger doesn't get you, the outdoor tap, or your indoor plumbing and radiators will.

I prefer having a 32A Commando socket.  Then if my charger breaks or becomes obsolete, swapping it out is easy.

It would be nice however if there is a solution, to match the likes of the Zappi. 

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