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EV CHARGING EQUIPMENT

John Peckham
I am hearing from my network of contractors, that have actually read the new 722, that they have been asking charging equipment manufactures for documentary proof to comply with Note 5 of 722.411.4.


They are getting knocked back for asking or in one case a Declaration that says the particular device complies with BS 7671. I think that is wrong to declare that as BS 7671 is an installation safety standard and not a product standard. I believe that as a minimum the equipment must comply with the Low Voltage Directive and be CE marked. I also believe that manufacturers have to issue a Declaration of Conformity. 


BS 7671 722 has numerous references to the various standards required such as BS EN 61851 that the equipment must comply with. I am thinking it may be illegal to offer the sale of equipment that does not comply with the Low Voltage Directive and is not CE marked?


I am hoping the countries top man of equipment safety standards, Paul Skyrme , sees this post and will come on and give us his expert view?


Has any forum member asked for a Declaration of Conformity from EV charging equipment manufacturers and received one?
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    Having designed a few  bits to go into vehicles over the years, I think part of the problem is that there is a collision of cultures about what is an acceptable risk and an adequate failure rate for a safety measure.


    A car has a great many single points of failure that could if they occured result in instant death in very credible conditions, and we are happy with that.  And the next time you hammer along the Mway  spare a thought for the single skin of the  tank of fuel slung underneath, or  the exhaust hot enough to set fire to paper or grass,  or the fact your track rode ends are each held by a single slightly rusting bolt, as are a number of other vital parts.


    Electrical installations on the other hand start with the principle of double fault to danger (fault from live to case AND open CPC perhaps) and then may well add 3rd and  4th layer defences. like RCDs and  bonding, insulated and sleeved.

    If we graded the fault risks in a car the same way as we do with fixed wiring most cars would be a C2 as they leave the factory.


    Of course cars do kill more people, a some thousands a year in the UK, and put perhaps 10 times that no in hospital, but mostly die to driver errors or external effects like falling trees. or playing children, not mechanical matters, so that is acceptable.

    I imagine that the designers of the car chargers were simply working to their normal standard, the fact it was mains is less of a consideration, rather than a conspiracy to make life hard.

    Also, even though it is clear to us,  I think the knowledge is not generally out there - even among folk who ideally would know better.  I have lost count of the no. of times I have sighed reached for a whiteboard pen and explained things like what exactly is PME, and why inverters on vehicles need an NE bond if you'd like an RCD to actually do anything, to other electronic designer  types, many of whom design power supplies and other significant stuff, there is a tendancy to stop thinking at the 3 pin connector at the top left of the diagram marked 'mains in', and treat the other side of it as not part of the current design.

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    davezawadi:

    I really don't see how these control signals in any reasonable system could cause additional risk Andy.




    Unfortunately, some of the control signalling for EVs to BS EN 61851-series (Mode 3 and Mode 4 - the protective devices in Mode 2 should cover upstream, at least if there's Type A RCD upstream) uses the protective conductor to the vehicle. The idea is that this also checks the integrity of the protective conductor connection.


    A simple N-E fault in the connecting lead or at the vehicle then causes DC residual current - unfortunately N and E are also connected upstream of the installation as well. The currents involved are unfortunately within  the "affects RCD" range.




    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.






    This is not the case - see above. Having said that, at least Type A would be recommended for modern installations.




    I note that Graham K pointed out that changing the design of electric car chargers in the future to class 2 is essentially impossible.






    I didn't say double insulated was impossible. I simply said 'They aren't and won't be until we have wireless charging, if that ever gets off the ground.' - a mere statement of fact, given that the conductive charging standards are now well established ... globally, regionally in CENELEC, and nationally in the UK. There are still a lot of vehicles already out there that will require charging equipment to the current standard, and it will take time for those to disappear.

     




    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.






    If you consider that we have plug-in petrol hybrids, which also have to meet the standard, then, just like with aircraft (even though aviation kerosene is normally only explosive in vapour form) avoidance of static is seen as important, through earthing the fixed electrical ground power, and also providing static discharge for a tending bowser. Earthing is even required for the topologies of Mode 4 rapid chargers that include electrical separation (see Annex K of the 4th Ed of the IET CoP for EV Charging Equipment Installation).


    In addition, there is a requirement to install EV charging in the curtilage of petrol filling stations. Avoidance of static is important there too.



    Overall, it's my opinion that, regardless of the rights and wrongs of where we are right now, within the time it will take to get to a point where all electric vehicles are double insulated, at least one of the following will have happened:



    1. Wireless charging will be a reality

    • An alternative technology will have arrived (fuel cells is one example)

    • The industry will have got completely fed up with the PME situation and resolved that one way or another.

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    I really don't see how these control signals in any reasonable system could cause additional risk Andy.



    It was just one theory - based on the apparent requirement in BS 7671 only applies to BS EN 62196 connectors - as these have CP and PP signals which as far as I can tell are 12V d.c., referenced to the c.p.c, and share the flex and connectors between the (mode 3) charge point and the vehicle. A simple short between one of these and say the N in the same connector would seem a possible source of d.c. within the loop the supply RCD sees.


    The other possibility is of course a fault between the vehicle's battery systems and mains - which I agree should be possible to design out. However I gather that at least one popular model currently on the market has a design that re-uses the same circuitry for both plug-in charging and while driving - so doesn't provide proper double-insulation between the a.c. and motive d.c. sides. Not ideal - and hopefully a bodge that VF drive or SMPSU manufacturers wouldn't have to resort to - but apparently where we are at the moment.

     

       - Andy.
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    0 Former Community Member

    davezawadi:

    I note that Graham K pointed out that changing the design of electric car chargers in the future to class 2 is essentially impossible.




    In the early days of modern electric mobility (around 2009) car manufacturers refused to limit themself to topologies that prevent DC-faults and now we have to deal with those shortsighted decisions.

    So the infrastructure had to cure that by stipulating a type B RCD or equivalent aproaches.

    But please keep in mind that in those days the automotive industrie was still considered a spearhead of technology.

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    would ELV be 1/ viable & 2/ "Safe" ?
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    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.
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    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.
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    Simon Barker:

    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.




    If on PME, not in accordance with either BS 7671 or ESQCR. The ESQCR prohibits the connection of a caravan or boat to PME, and Mobile/Transportable Units are generally classed as Caravans for this legislation, so Section 717 of BS 7671 has restrictions on connection of those to PME as well!



    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. ?



    Well, see above - why is a car any different to a caravan, as you quite rightly say !



    How can it be so difficult?



    It wouldn't be if the EV mains interface were double insulated, but that's another story. They aren't and won't be until we have wireless charging, if that ever gets off the ground.



    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?



    Neither should Mobile & Transportable Units, and neither should should boats.


    "Just TT the supply" is effective, IF it's done properly and safely ... which includes separation below ground from metalwork (pipes, cables etc.) connected to the PME - for caravans and boats, GN 7 recommends 10 m, based on data from BS 7430.  The other problem, is that BS 7671 requires simultaneously accessible exposed-conductive-parts to be connected to the same earthing system - so if you can't connect to the PME, that can't happen.


    And you see the big problem that's present especially for small curtilage properties, like most homes ...

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    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?
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    Chris Pearson:




    Sparkingchip:

    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.




    Oh dear! They don't seem to understand the difference between the capacity of the fuse holder and the rating of the fuse within it; and no mention of the earthing arrangement.


     








    There are a couple of points in the video it where I tried to freeze frame for closer inspection 

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