@cm @weezmgk @Habrok42 @momo @das_menschy @Wifiwits @cgudrian @LilahTovMoon That’s my suspicion. The adapter probably doesn’t properly detect L/N swapping and only checks to see if N and PE have potential. Wire it sufficiently incorrectly and it puts hot on the output. Or maybe the car assumes N and PE are the same thing and has the chassis connected to N (or to both).

As for how to detect it, once you have power, it’s pretty straightforward to make a DC reference and check for AC potential between that reference and each input line. You can’t confirm whether a given line is actually earth versus something with DC bias, but you can tell whether AC exists in the absence of significant load. Think like running a set of non-contact voltage testers. Then only engage the relays (or IGBTs or whatever else you may want to use) to draw from the feed if you don’t detect AC on the PE line or N line.