EVSE Earth leakage limits

Anyone know what earth leakage current limit applies for an EVSE?

For regular Type 2 Mode 3 32A 7kW or 21kW AC charge points.

For the purposes of in service inspection and testing is there an earth leakage limit specified by an applicable product standard?

I'm not talking about DC leakage currents (whole different can of worms).

They are (generally) built double insulated so does a 0.25mA Class II limit apply?

They supply an EV which is definitely Class 1, they are not handheld but are certainly a similar touch voltage shock risk, so does a 0.75mA limit apply?

They are fixed equipment (strictly the EV isn't fixed but that's splitting hairs), but not motor operated (certainly while charging), so does a 3.5mA limit apply?

Your learned thoughts appreciated?

Parents
  • AC EVSE (without vehicle) has the following touch-current limits according to BS EN IEC 61851-1:2019 and BS EN 61851-22:2002.

    The test is made when the EVSE is functioning with a resistive load at rated output power.

    In addition, BS EN 61851-21 permitted up to 5 mA of additional "leakage" from the vehicle.

    Therefore, up to 8.5 mA AC may be expected - I always tell people to expect 9-10 mA combined because occasionally, it's on the verge of "might just operate" the 30 mA RCD mandated by BS 7671. There's certainly no overhead for other equipment on the same circuit.

    Plus on the protective conductor itself (between PC and PE) there is the DC/pulsed DC of the pilot, don't forget.

  • This is a new one to me, and it seems quite oddly worded - as I presume you have a copy, could you clarify what is a 'network pole' in this context please ?  It also reads as if touch current is interpreted quite differently to the way we would for an appliance and really means non diverted CPC current.

    M

  • could you clarify what is a 'network pole' in this context please

    Live conductor - not uncommon.

    It also reads as if touch current is interpreted quite differently to the way we would for an appliance and really means non diverted CPC current.

    I think you can view it like that, but again this is becoming more common in product standards.

  • Is it fair to say it appears that the protective conductor currents may approach the threshold specified in Regulation 543.7, which pertains to high protective conductor currents exceeding 10 mA ? 

  • yes but actually it sounds like it could be a lot higher, the protective conductor currents may be anything - amps if you like!

    As apparently only the CPC current that comes L-E directly is being considered. other currents flowing in the CPC that may still be a consequence of the operation of the charger or the car attached, between the CPC and other paths to earth such as mechanical mountings or external reference electrodes etc are ignored.

    I can see an argument for ignoring diverted neutral current coming from the network, as there is very little one can do about that as product design, apart from TT,  but it feels odd to ignore currents in the CPC generated by the system under test, especially in a system that uses the bit of CPC between car and charger  as part of its signalling path.

    Mike.

Reply
  • yes but actually it sounds like it could be a lot higher, the protective conductor currents may be anything - amps if you like!

    As apparently only the CPC current that comes L-E directly is being considered. other currents flowing in the CPC that may still be a consequence of the operation of the charger or the car attached, between the CPC and other paths to earth such as mechanical mountings or external reference electrodes etc are ignored.

    I can see an argument for ignoring diverted neutral current coming from the network, as there is very little one can do about that as product design, apart from TT,  but it feels odd to ignore currents in the CPC generated by the system under test, especially in a system that uses the bit of CPC between car and charger  as part of its signalling path.

    Mike.

Children
  • currents in the CPC generated by the system under test” Is this matter typically disregarded, or is it simply not given due consideration?

  • but it feels odd to ignore currents in the CPC generated by the system under test, especially in a system that uses the bit of CPC between car and charger  as part of its signalling path.

    currents in the CPC generated by the system under test” Is this matter typically disregarded, or is it simply not given due consideration?

    But surely those are between PE and PC between the vehicle and the EVSE only ... not back through the supply PE unless there's an N-PE fault?

  • IF that bit of the CPC went high impedance, and a person got connected in its place, would i hurt ? I.e does the standard limit the open circuit voltage or short circuit current that may flow. ?

    But surely those are between PE and PC between the vehicle and the EVSE only ... not back through the supply PE unless there's an N-PE fault?

    or, as you yourself have pointed out to me in another post about TT that seems to be very hard to find on the forum at the moment,  a connection between the body of the car and any sort of earth that is in addition to the ones you expect.

    Now I can easily visualize such a contact as being with an adjacent car, or a metal guard rail, shopping trolley etc. For now, electric cars are expensive and rare and probably in the hands of folk who park carefully and  keep them lovingly shiny and the paint job intact. Bur, eventually electric vehicles will drift down to the rest of us, including those who on a bad day  occasionally park badly and or leave trailers and so on attached to the car once parked.

    Mike

  • So surly the EV industry will need to adapt to these safety concerns? 

  • The manufacturers work to harmonized European vehicle standards.  Weird quirks of BS7671 aren't really a consideration.