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Why is it okay for marine vehicles to use the 30 mA standard but not terranean vehicles? Is there an EVSE that doesn't have this problem? This discussion migh

Why is it okay for marine vehicles to use the 30 mA standard but not terranean vehicles? Is there an EVSE that doesn't have this problem? This discussion might interest you: https://old.reddit.com/r/evcharging/comments/15blqlj/how_some_manufacturers_are_handling_gfci_breaker/jtrgm7s/ https://old.reddit.com/r/evcharging/comments/15blqlj/how_som...

atoav 2y ago
I would be very interested in "stray inductance and capacitance" are meant to produce a 5mA flow out of your circuit. Or let's phrase it like that: If the proper cables are used and if the wiring isn't absolute dogshit next to other absolute dogshit the cited reason isn't the reason. Try to induce 5mA of foreign circuit into a cable on purpose and you will see what I mean. Measuring equipment exists so we don't need to guess here.. The issue is more that manufactureres calculated with a 30mA threshold for ages and if they did a bad job, they produced equipment that just barely made that threshold. Typically such norm changes are known well ahead, I am more familar with European norms, but changes like these are known a decade ahead. So it isn't as if manufacturers of such equipment are suddenly surprised by new regulations. And if the new rule starts to work that should only affect newly built unints (or units where the electrical installation is renewed). So if your EV charger trips the GFCI because of bad electrical wiring, thr wiring likely had to be replaced due to new norms anyways.. Why the thresholds for different areas differ is usually a mix of historical reasons, lobbying and a "we didn't get around to that yet". It is hard to answer such questions in isolation, maybe marine equipment has other maintenance cycles, crazier cabling requirements, maybe there are fire suppression measures that allow to relax that requirement more, maybe it doesn't make sense at all. As someone who has read through nearly 100 GB of norm PDFs I can assure you that just comparing two thresholds in isolation is practically worthless if you ignore the other differences in the rules.
- Workaccount2 2y ago
  My guess is that it is likely from Y caps filtering common-mode noise. They are great for filtering EMI to pass strict emissions regs, so it is easy to use them liberally. I'll admit I don't know what kind of currents they see, but 5mA on transients wouldn't be particularly surprising. There is also the factor of how sensitive the GFCI is.
  - photon_rancher 2y ago
    Over 100nF of unbalanced Y-caps is needed at 60Hz/120V to see 5mA gnd current. That would be a big Y capacitor (2.2n or lower is common) and they’re usually used in a balanced configuration which would reduce it further. If a Y capacitor fails on one leg, you have a problem. If a Y capacitor fails is only present on one leg, you have a problem. And if it’s resistive leakage, that’s almost a watt of dissipation - also huge and probably a short in a cable and potentially a fire risk. 5mA is a massive threshold for well designed devices
    - Workaccount2 2y ago
      It would be fast transients that are in the kHz to MHz and over 120V. Thats why I wonder about the sensitivity of the GCFI. Can it tolerate 5mA for 50ns?
      - atoav 2y ago
        It should, typically trip times should be in the single digit miliseconds range (the idea is to stop within half of a 60/50Hz cycle).

atoav 2y ago

I would be very interested in "stray inductance and capacitance" are meant to produce a 5mA flow out of your circuit. Or let's phrase it like that: If the proper cables are used and if the wiring isn't absolute dogshit next to other absolute dogshit the cited reason isn't the reason. Try to induce 5mA of foreign circuit into a cable on purpose and you will see what I mean. Measuring equipment exists so we don't need to guess here.. The issue is more that manufactureres calculated with a 30mA threshold for ages and if they did a bad job, they produced equipment that just barely made that threshold. Typically such norm changes are known well ahead, I am more familar with European norms, but changes like these are known a decade ahead. So it isn't as if manufacturers of such equipment are suddenly surprised by new regulations. And if the new rule starts to work that should only affect newly built unints (or units where the electrical installation is renewed). So if your EV charger trips the GFCI because of bad electrical wiring, thr wiring likely had to be replaced due to new norms anyways.. Why the thresholds for different areas differ is usually a mix of historical reasons, lobbying and a "we didn't get around to that yet". It is hard to answer such questions in isolation, maybe marine equipment has other maintenance cycles, crazier cabling requirements, maybe there are fire suppression measures that allow to relax that requirement more, maybe it doesn't make sense at all. As someone who has read through nearly 100 GB of norm PDFs I can assure you that just comparing two thresholds in isolation is practically worthless if you ignore the other differences in the rules.

Workaccount2 2y ago
My guess is that it is likely from Y caps filtering common-mode noise. They are great for filtering EMI to pass strict emissions regs, so it is easy to use them liberally. I'll admit I don't know what kind of currents they see, but 5mA on transients wouldn't be particularly surprising. There is also the factor of how sensitive the GFCI is.
- photon_rancher 2y ago
  Over 100nF of unbalanced Y-caps is needed at 60Hz/120V to see 5mA gnd current. That would be a big Y capacitor (2.2n or lower is common) and they’re usually used in a balanced configuration which would reduce it further. If a Y capacitor fails on one leg, you have a problem. If a Y capacitor fails is only present on one leg, you have a problem. And if it’s resistive leakage, that’s almost a watt of dissipation - also huge and probably a short in a cable and potentially a fire risk. 5mA is a massive threshold for well designed devices
  - Workaccount2 2y ago
    It would be fast transients that are in the kHz to MHz and over 120V. Thats why I wonder about the sensitivity of the GCFI. Can it tolerate 5mA for 50ns?
    - atoav 2y ago
      It should, typically trip times should be in the single digit miliseconds range (the idea is to stop within half of a 60/50Hz cycle).