EV CHARGING EQUIPMENT

So if seen installed as supplied we can start writing up the observations on an EICR.

Referring to NAPIT Codebreakers throws up at least two C2 rated observations.



From the data sheet:


The Masterplug EVH132S1SP mode 2 charging unit is fitted with a type B RCBO for additional local protection.


The Masterplug EVH132S1SP EV mode 2 charging unit can be classed as being EV Ready. The EV ready unit provides the homebuilder with a low cost, future proof solution that, as well as providing EV charging in Mode 2 format to satisfy planning, can also be used an outdoor IP66 rated domestic 13 Amp socket. This unit is ideal for the homebuilder.


Andy Betteridge 

So the old adage, you get what you pay for, holds true.


Spend £70 or less on a EV looky likey consisting of a labeled 13-amp single socket and a near useless RCBO in a plastic box and you will need to spend a couple of hundred quid on a consumer unit with a new consumer unit with a type B 30 mA  DP RCD in it on top of the other installation charges to top the EV battery up at a rate that allows around eight miles of driving for each hour charging, 


Or you can spend a considerable amount of money on a top end EV charger that can possibly just be connected into a spare way in your existing consumer unit and charge the EV one hell of a lot faster. Though the possibility of the installation costing over £20K with a supply upgrade to three-phase.


Installation of the dirt cheap "charger" could easily cost half as much again or more than the expensive charger.


Andy Betteridge

Andy, I don`t think that gives you any surprise. You knew it already. Life has lots of instances like that

Does anyone have any technical documentation (from IEC or whatever) as to why EV charging points need DC sensitive RCDs? I have a large inverter MIG welder (450A, approx 15kVA max) which is basically a large switch mode PSU. It has all the modern bells and whistles like PF of 1 and obviously gives DC out, just like an electric vehicle. Does this mean that its socket (3ph 63A) needs a fancy RCD if I were to fit one? After some analysis I cannot see why any reasonable fault would give a DC leakage sufficient to prevent normal RCD operation, and therefore wonder if this EV requirement is even sensible, or thought up by someone with nothing better to do or perhaps a manufacturer wanting to increase sales revenue. It is often quoted that this is due to the fact that the mains comes to a rectifier first which could pass current in only one direction, but whether this prevents RCD operation is a moot point. It would also require multiple faults (earth fault and electronic fault which did not stop operation), which is pretty unlikely. Perhaps I need to do some more experiments with rectified leakages? Thoughts welcome....

I'm still wondering why it is that we've been running boats, caravans, burger vans, garden tools and pressure washers from outdoor sockets for years, and all it needs is a single RCD protecting the circuit.  But the moment someone wants to charge an EV, it needs some box full of magical pixie dust, or everyone who touches the vehicle when it's on charge will instantly be electrocuted. ?


How can it be so difficult?


Edit: OK, so I think caravans shouldn't be on TN-C-S.  So just TT the supply.  If the EV charge point is outdoors, is that too hard?

Spend £70 or less on a EV looky likey consisting of a labeled 13-amp single socket and a near useless RCBO in a plastic box and you will need to spend a couple of hundred quid on a consumer unit with a new consumer unit with a type B 30 mA  DP RCD in it

Perhaps cat & pigeons time. I've been re-reading 722 and noticed that the requirement for a B-type RCD could be read as applying only to charge points with BS EN 62196 outlets (whether fixed sockets or trailing lead connectors) - and so not BS 1363 ones (or BS EN 60309 ones for that matter).


I think the wording isn't clear - specifically whether "socket-outlet or vehicle connector complying with the BS EN 62916 series" should be read as 'any kind of socket outlet, or BS EN 62916 vehicle connectors' or 'socket-outlets complying with BS EN 62916 or vehicle connectors complying with BS EN 62916' (why don't we use brackets in English?). But as the same phrase is used several times further on in 722.55.101.0.201.1 where it 'clearly' meant to mean the 2nd option - so I'm fairly confident that the authors didn't mean to include BS 1363 sockets in the requirement.


Then there's the question of whether that interpretation makes logical sense and is safe. I guess one point of view is that if the source of these d.c. fault currents is thought to be the d.c. 'pilot' wires in BS EN 62916 charge-point to vehicle wiring system (the ones that communicate acceptable charging rates, that the vehicle is connected and so on) - then the absence of these in a BS 1363 plug/socket system might be seen as reducing the risk. OK these signals are present further downstream, after the in-lead box of tricks - but then that box of tricks was (originally) meant to be plugged into an ordinary socket which should have no presumption of upstream B-type RCD protection - so that box should provide whatever protection is necessary (but that'll be down to whatever product standard it's meant to comply with rather than BS 7671).


So maybe, just maybe, there is a market for these 'mode 2' charge points.


   - Andy.

I really don't see how these control signals in any reasonable system could cause additional risk Andy. The usual stated reason for type B RCDs is that they detect DC current as faults, rather than preventing AC fault detection by saturating the transformer. That was the reason for my post above, because it suggests that any equipment using a SMPS should have a type B RCD, which is of course foolish, or possibly necessary to comply with the latest regulations.


I note that Graham K pointed out that changing the design of electric car chargers in the future to class 2 is essentially impossible. Why? I see very little difficulty with most SMPS designs to make them class 2, with the possible exception of EMC, which is somewhat more difficult. All we need is an edict that all cars must be class 2 from next year, and no manufacturer will have any great difficulty complying if they wish to sell any cars. After all these are expensive high tech products with massive development teams available, so adding a bit of insulation cannot be that difficult. In all designs the battery is completely isolated from the mains supply, so the basic separation of systems is already present. Thus the risk becomes very small and car charging very straightforward wherever one plugs in.