There doesn't seem to be much point in a 30mA RCD if the socket outlet is DC (mode 4) - it's not going to provide additional protection (e.g. in the case of a damaged flex) like it would for a directly connected AC system (modes 1-3).

I suspect NOTE 2 to 722.531.3.101 is the giveaway - it's still "under consideration"....

  - Andy.

Hi Andy, thanks for your response.

I hear what you say about Note 2 of 722.531.3.101. I also understand that the RCD won't be providing additional protection on the DC side.

However, If you look to Appendix J of the EV charging CoP (5th edition), you'll notice that it calls for electrical separation to be established using an isolating transformer to BS EN 61558-2-4. EV charging manufacturers are stating that galvanic isolation is provided but not by means of an isolating transformer to BS EN 61558-2-4.

Furthermore, If you look to section J2 of Appendix J, you'll see the following: BS 7671 does not, at present, require RCD protection for the DC output to the vehicle. An appropriate RCD should, however, be provided on the AC input to DC charging equipment without separation, according to Regulation 722.531.3.101.

Am I missing something?

Hi Andy, thanks for your response.

I hear what you say about Note 2 of 722.531.3.101. I also understand that the RCD won't be providing additional protection on the DC side.

However, If you look to Appendix J of the EV charging CoP (5th edition), you'll notice that it calls for electrical separation to be established using an isolating transformer to BS EN 61558-2-4. EV charging manufacturers are stating that galvanic isolation is provided but not by means of an isolating transformer to BS EN 61558-2-4.

Furthermore, If you look to section J2 of Appendix J, you'll see the following: BS 7671 does not, at present, require RCD protection for the DC output to the vehicle. An appropriate RCD should, however, be provided on the AC input to DC charging equipment without separation, according to Regulation 722.531.3.101.

Am I missing something?

However, If you look to Appendix J of the EV charging CoP (5th edition), you'll notice that it calls for electrical separation to be established using an isolating transformer to BS EN 61558-2-4. EV charging manufacturers are stating that galvanic isolation is provided but not by means of an isolating transformer to BS EN 61558-2-4.

I guess your other option is to provide an isolating transformer upstream of the EVSE, so that the EVSE and its immediate supply circuit are protected by separation.

   - Andy.