[Amps] Safety grounding - was Mains Isolation Transformer

[Peter Chadwick]

It must be remembered that the rules (and supply arrangements) are different between countries, and the UK requirements when you take PME (Protective Multiple Earthing) into account can give problems with external grounds. Especially if the RF ground and the mains ground are only connected by the lead to the equipment - in this case, a ruptured neutral can cause major problems, like burning the house down! In my case, the neutral is connected to a ground rod at base of the electricity pole in the garden, the 'safety ground' for the house is a ground rod by the front door, and the RF grounds are rods around the tower and the mast for the VHF antennas. As a result, my RF grounds are lower resistance than the safety ground, and I don't have the problem of the possibility of a ruptured neutral causing problems.
The comments about not using the ground lead as a current  return apply universally, though. Some of the older ARRL handbooks have designs which do, though. I always work on the basis that the neutral should be considered as 'live' conductor, even though it is at or near ground potential. Then I use double pole switches to switch live and neutral, and fuse the live side only.

73
Peter G3RZP