Hi, I've actually had this before as well in the old goldstream, being a sparky i had a multimeter handy and promptly set about checking things, starting with the source of supply and sure enough it was actually the caravan parks power at fault. I had about 60v between the earth poll of the gpo and the ground, litterally, i stuck the multimeter probe into the ground. When i reported this to management they told me the park was closing down in a few months to make way for an apartment blocks. In saying that i still would recommend you have checked out just to be on the safe side