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
  • Sorry, I am not quite picking up on what Mike is saying, can you just clarify if this is touch current as measured through a body model?

  • I think, which is why I queried it, they seem to allow any no of amps to flow in the CPC, so long as it is not flowing L-E, In other words L and N currents balance - i.e. in a standard worded like that,  you are not regulating  the shock a victim would receive if the CPC broke and their body replaced it, but the rather the result of an RCD-like measurement of residual supply current, phase currents minus neutral currents  sort of thing. 

    On a stand alone item like a kettle on an insulated worktop, the two are the same, but not for anything that has any degree of installation that allows a second earth path.

    As a silly extreme imagine a double wound transformer with its primary wired L-N and its secondary wired between the supply CPC and some plumbing or building steel that is casually earthed , The CPC current is not derived from a pole of the supply, so L-N currents balance but a CPC current  is very much flowing , and if the voltages and series resistances were chosen right then breaking the cpc and holding both sides could be painful ;-) 

    As far as I know most PA testers actually do measure CPC current, with varying degrees of error on non-sinusoidal waveforms, and for the purposes of the CE mark, the test gear that gets used in the labs does too - well at least it does on the stuff we CE mark,which is not electric  car chargers to be fair.

    It just seems a strange way to set a limit that is really about shock protection, hence the query.

    Mike.

Reply
  • I think, which is why I queried it, they seem to allow any no of amps to flow in the CPC, so long as it is not flowing L-E, In other words L and N currents balance - i.e. in a standard worded like that,  you are not regulating  the shock a victim would receive if the CPC broke and their body replaced it, but the rather the result of an RCD-like measurement of residual supply current, phase currents minus neutral currents  sort of thing. 

    On a stand alone item like a kettle on an insulated worktop, the two are the same, but not for anything that has any degree of installation that allows a second earth path.

    As a silly extreme imagine a double wound transformer with its primary wired L-N and its secondary wired between the supply CPC and some plumbing or building steel that is casually earthed , The CPC current is not derived from a pole of the supply, so L-N currents balance but a CPC current  is very much flowing , and if the voltages and series resistances were chosen right then breaking the cpc and holding both sides could be painful ;-) 

    As far as I know most PA testers actually do measure CPC current, with varying degrees of error on non-sinusoidal waveforms, and for the purposes of the CE mark, the test gear that gets used in the labs does too - well at least it does on the stuff we CE mark,which is not electric  car chargers to be fair.

    It just seems a strange way to set a limit that is really about shock protection, hence the query.

    Mike.

Children
  • I think, which is why I queried it, they seem to allow any no of amps to flow in the CPC, so long as it is not flowing L-E, In other words L and N currents balance - i.e. in a standard worded like that,  you are not regulating  the shock a victim would receive if the CPC broke and their body replaced it, but the rather the result of an RCD-like measurement of residual supply current, phase currents minus neutral currents  sort of thing. 

    Agreed ... that is effectively the approach taken in some standards.

    As a silly extreme imagine a double wound transformer with its primary wired L-N and its secondary wired between the supply CPC and some plumbing or building steel that is casually earthed , The CPC current is not derived from a pole of the supply, so L-N currents balance but a CPC current  is very much flowing , and if the voltages and series resistances were chosen right then breaking the cpc and holding both sides could be painful ;-) 

    Yes, I do see where you're going. But that's a number of things going wrong in sequence rather than instantaneously, so therefore not "single fault conditions" or "additional protection".

    It just seems a strange way to set a limit that is really about shock protection, hence the query.

    BS EN IEC 62368-1 is very interesting. Doesn't align with BS EN 61140 at all really - especially where "SELV" and "PELV" are concerned, hence limiting the use of electronic supplies for certain special locations in BS 7671:2018+A2:2022.