Glan gluaisne
Active Member
Happy to help. If the electrician questions why a Type B is needed (and, to be fair, it isn't yet that well understood by some), then just mention that it's now a requirement that's in the wiring regs, section 722, paragraph 531.3.101:
This part of the regs has been subject to recent amendment. Although the requirement for a DC tolerant RCD (Type B or Type EV) has been around for many years now (since about 2012, IIRC) it was largely ignored, primarily because Type B RCDs used to be prohibitively expensive (around £400 or so back when charge points were first being installed here in the UK).
BTW, "electrical separation" in the above refers to the use of an isolation transformer, but one rated for a 32 A charge point would cost a fortune and be far too large to fit in most domestic situations. I'm not even sure that anyone actually makes one, either.
722.531.3.101 Unless supplied by a circuit using the protective measure of electrical separation, each charging point incorporating a socket-outlet or vehicle connector complying with the BS EN 62196 series shall be protected by an RCD having a rated residual operating current not exceeding 30 mA.
Except where provided by the EV charging equipment, protection against DC fault currents shall be provided by:
(i) an RCD Type B, or
(ii) an RCD Type A or Type F in conjunction with a residual direct current detecting device (RDC-DD) complying with BS IEC 62955 as appropriate to the nature of the residual and superimposed currents and recommendation of the manufacturer of the charging equipment.
RCDs shall comply with one of the following standards: BS EN 61008-1, BS EN 61009-1, BS EN 60947-2 or BS EN 62423.
NOTE 1: Types of RCD are described in Regulation 531.3.3 in respect of their behaviour when exposed to DC components and
frequencies.
NOTE 2: Requirements for the selection and erection of RCDs in the case of supplies using DC vehicle connectors according to the BS EN 62196 series are under consideration.
NOTE 3: An RCD Type A or Type F in conjunction with an RDC-DD can be arranged with the RDC-DD inside the EV charging
equipment and the Type A or Type F RCD upstream in either the charging equipment or the installation.
This part of the regs has been subject to recent amendment. Although the requirement for a DC tolerant RCD (Type B or Type EV) has been around for many years now (since about 2012, IIRC) it was largely ignored, primarily because Type B RCDs used to be prohibitively expensive (around £400 or so back when charge points were first being installed here in the UK).
BTW, "electrical separation" in the above refers to the use of an isolation transformer, but one rated for a 32 A charge point would cost a fortune and be far too large to fit in most domestic situations. I'm not even sure that anyone actually makes one, either.