Tesla - thanks for the helpful hints. I will try this if I am given the ok by the home owner to proceed with the troubleshooting.
I was brought in by the plumber as I said on an emergency basis. Owners showed up when I thought I had the problem licked but then the screwy things started to happen after they left. My concern now which I am sure you can understand is that I have already spent hours troubleshooting this problem and at this point don't even know if I willo be paid because the problem was not solved. Until I get the go-ahead from the owner I am not doing anything else.
In situations like this you can loose your shirt as I am sure you know. I could spend many hours troubleshooting with no definite results or fix and the owener says why should I pay you if you did not fix the problem. I think it is more to the point now if I want to really tackle this problem and get involved with more than I can handle with my schedule of work already booked.
I don't have a megger; should get one I know.
The panel does not seem to be that old but with the house being vacant for so long god knows what could have caused this problem. The previous tenants could have played "Mr. Handyman" as you said.
Funny, a Doctor gets paid to diagnose a health problem and even if he does not find the problem he still gets paid by the insurance company. An electrican can spend days troubleshooting something and not get paid for his time. Scenarios like this trouble me.
Thanks again for your suggestions.
