Re: Bad earth.
Sounds like a similar situation with domestic PME (Protective Mutiple Earth) main systems where the earth and neutral are basically the same. Often found where mains is delivery directly by overhead wire.
All conductive surfaces have to be earth bonded, which means that they are connected to the neutral line.
Any failure of the neutral conductor into the house effectively makes all those surfaces live through any switched on device.
Makes a good case for a local ground spike.
Biting the hand that feeds IT
