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Another "EV Charger mounted on a metallic building with PME supply" question

Former Community Member
Former Community Member
Hi All,


I'm new to the forum, but not new to being a sparky, but through it was time i got online and got involved in the community. I know this previously came up on this thread in the previous incarnation of the forum, but the OP finally resolved to move the EV points further away from the metallic building, so it didn't really get answered.

Firstly, i am an experienced sparky and an OLEV approved EV chargepoint installer with many installs under my belt, but i've been working up from installs in homes and small businesses knowing this question would come up one day - now that time is here.

I have been asked to install a double socket single phase charge point on this commercial unit which is metal clad (this is really the only option for a place to put the pint without massive excavation through the car park which is many sim of tarmac. It's a large industrial unit with a TN-S 3-phase supply, approx 500kVA demand after diversity. The point is coming from a sub board near the location of the charge point (about 15m). The only issue is the fact i need to assume the TN-S could be PME as the DNO will not guarantee otherwise, but the metal clad building is obviously bonded to the PME terminal. The customer does not want any additional structures or enclosures putting up, the loading can not be guaranteed to be balanced as there is various equipment starting a stopping all day on different phases which discounts 722.411.4.1(i), and there is literally no open ground for at least 150m so i've discounted 722.411.4.1(ii), so this only leaves Electrical separation as a protective measure against an open neutral fault as far as i can see. I have 2 questions:


1. Am i correct that this is the only option? Is there anything else i should consider. I have a quote for the transformer and it isn't too expensive, and although it will need a bit of manhandling in to place at 80kg, it's a viable option. But i know a lot of people have concerns over this method in practise.


2. In the CoP for EV Charging Equipment Installations 3rd Ed., Figure 5.3. it shows the CP for the EV charge point originating from the N between the transformer and the RCD for the chargepoint. Doesn't this contradict 722.312.2.1 in BS7671, as its effectively a PEN conductor at that point? Or does 722.413 override this?


Cheers


Lee


P.s. question 3. in addition, surely the risk here isn't any greater than with the EV chargepoint installed that without, and someone standing on the same tarmac and leaning on the buildings steelwork or cladding? I obviously want to meet the regs, but isn't there something missing for this sort of situation which will likely become more common in the next few years.
  • 0

    AJJewsbury:

    One other thought (sorry, going off at a tangent now) ... should these devices be subject to any testing? (either on testing or during periodics). I guess they'd share some basic technology with RCDs (current/voltage sensing, comparison with a threshold and triggering mechanical contacts) - and if after all these years RCDs are considered vulnerable to failure should we not take similar precautions with these new devices?


    I guess a variac and a stopwatch would do - but maybe there's a market for a new kind of tester...


      - Andy.




    The same argument could be levelled at mcb's ...

  • 0
    Indeed, and the argument has always been that MCBs are relatively simple, not relying on a delicate balance like an old style RCD, or lots of internal electronics, like a new style RCD or RCBO, and they are hard to test, needing large fault currents. (Although to be fair at least the 'dead short' magnetic part and the mechanical behaviour of an MCB can be tested with a car battery and a couple of jump leads. or perhaps a welding supply, so it is not so hard to detect the obvious fakes on the market if you have to - .)


    And of course MCBs are sold as a replacement for fuses, which cannot sensibly be tested in advance of real operation, and at least in the UK, are backed up by a company fuse, so failure of the breaker to open is not a danger to life, though some thin cable may need replacement.


    Charge points on the other hand combine a lot of risk factors, especially public ones - the risk of damage by connection of a defective car, water ingress into connectors, connectors being run over, damage by surges on the network, lightning induced currents in some locations and of course they are jammed full of complex electronics, and this includes a special earth fault detection mechanism. Given their cost I can imagine the type B RCD counterfeiters rubbing their hands with glee if they knew they would  not be tested
  • Former Community Member
    0 Former Community Member

     





    My only issue is that the Zappi isn't suitable for this install as it's not the right product and also isn't applicable with the OLEV, and PodPoint only really install their own points. It would be great for someone to market and mass produce this device above so we can install them instead. I would do it myself if i was in the right position to start another business! Lol.


     






    Just had another quick look, and they may well be OLEV funded,

     

     aca629c257e08298e903f69e9373e104-huge-olev.png

  • 0

    so you (like me) can get your thoughts in now.



    I already have!

       - Andy.
  • Former Community Member
    0 Former Community Member

    Naj93:




     





    My only issue is that the Zappi isn't suitable for this install as it's not the right product and also isn't applicable with the OLEV, and PodPoint only really install their own points. It would be great for someone to market and mass produce this device above so we can install them instead. I would do it myself if i was in the right position to start another business! Lol.


     






    Just had another quick look, and they may well be OLEV funded,

     

     aca629c257e08298e903f69e9373e104-huge-olev.png

     

     




    Sorry Naj, i wasn't clear on this - the Zappi is OLEV approved, but only for the EVHS (home charging). This is a workplace install so they need to also be on the WCS for workplace charging. There are differing requirements for this. 

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