Wayne Dohnal wrote:
Because of capacitive and/or inductive coupling, an ungrounded RV will assume a potential above ground potential, at a non-hazardous current level. If the coupling was perfectly even between the ground and hot and neutral, a 30 amp RV would float at 60 volts. Most power converters are a major contributor to this effect, but even the wiring plays a role.
So I looked into this and discovered that the RFI filters in a convertor's switching power supply can cause current leakage. I learned something...thank you. However, I still stand by my concerns that the trailer needs to be checked for grounds (or shorts if it is an older style trailer with the grounded conductor bonded to the frame). It would be interesting to see what happens after he uses a good grounded cord. (Does the breaker trip which would, of course, indicate higher current leakage than just the RFI filter?) I would also like to know if he has a GFI outlet that he can use. Of course, if it's the RFI leakage then the GFI will/should trip if there is no other problem. Also, perhaps a outlet tester that he can plug into his garage outlet to test it for adequate ground and/or reverse polarity. No matter what, I am glad he is purchasing a grounded extension cord. That was the best advice given. Now to wade through the link posted above my original post :)
