[soapstone]

Sure, I''ve seen it in 3 phase systems. We once had an electrician get his color codes backwards. Was that way for years,,, until we connected two computers on opposite ends of the building with an older style of connection. There was 208 volts between the drains (signal grounds) It did similar.

I think this is why it''s such a good idea to either use an isolation transformer or to keep the grounds separate between AC and DC on mixed systems like a boat with AC.