It is the charging point that requires additional protection by 30 mA RCD, not charging equipment.

RCD protection of DC outlets is not really supported by "AC RCDs" (of the types specified in BS 7671).

Bh said:

An appropriate RCD should, however, be provided on the AC input to DC charging equipment without separation, according to Regulation 722.531.3.101.

This is good practice, but I understand that "leakage currents" may, in some cases, make 30 mA RCD protection impractical.

HOWEVER, I think the thing that is being "missed" is that 722.531.3.101 also contains requirements for selection of RCD Type. Where RCDs are required for ADS (e.g. TT system on AC side, or where disconnection times can't be met by OCPDs), the TYPE of the RCD is selected according to 722.531.3.101 where separation is not achieved - you will, effectively, need a Type B because of the possibility of DC leakage currents

It is the charging point that requires additional protection by 30 mA RCD, not charging equipment.

RCD protection of DC outlets is not really supported by "AC RCDs" (of the types specified in BS 7671).

Bh said:

An appropriate RCD should, however, be provided on the AC input to DC charging equipment without separation, according to Regulation 722.531.3.101.

This is good practice, but I understand that "leakage currents" may, in some cases, make 30 mA RCD protection impractical.

HOWEVER, I think the thing that is being "missed" is that 722.531.3.101 also contains requirements for selection of RCD Type. Where RCDs are required for ADS (e.g. TT system on AC side, or where disconnection times can't be met by OCPDs), the TYPE of the RCD is selected according to 722.531.3.101 where separation is not achieved - you will, effectively, need a Type B because of the possibility of DC leakage currents

Graham,

first and foremost, thanks for the reply. It's quite amazing to think someone can post a question on this forum and speak directly with the lead author of the EV charging CoP. It goes to show how good of a resource this forum is! Straight from the horse's mouth...

I'd agree that there is a real need (in most cases) for a type B RCDs because of the possibility of DC leakage currents, the last thing we want is the RCD to be blinded. I also think it's important to consider the issues associated with having type B RCDs downstream of type A RCDs, I've seen it overlooked a number of times.

gkenyon said:

Bh said:

An appropriate RCD should, however, be provided on the AC input to DC charging equipment without separation, according to Regulation 722.531.3.101.

This is good practice, but I understand that "leakage currents" may, in some cases, make 30 mA RCD protection impractical.

Could you please explain why it's considered good practise? After all, you did say the following:

gkenyon said:

RCD protection of DC outlets is not really supported by "AC RCDs" (of the types specified in BS 7671).

thanks, Bh.

Bh said:

Could you please explain why it's considered good practise?

Whilst the words are agreed by Committee, I can give a personal opinion here being that in converters without separation, you're effectively connecting mains through a controlled rectifier and a bit of electronics. If the electronics break down somehow, it's theoretically possible you're connected to the AC mains.

Leakage is an issue, so a 30 mA RCD on the AC side might not be possible ... so if you have a TN system on the AC side, it's really this is a question to the manufacturer as to whether an RCD is necessary on the AC side, and what rating  and type should it be?