>> Some projects I worked on involved such systems (control cables) and
>> the ground potentials with a/c units switching on and off and other big
>> loads in the building were unmanageable. You can get 3Vac between
>> ground and neutral in the same room, without any noise source, let
>> alone 50 meters away.
>
> It's a real eye opener when you connect a cable, and it starts to melt.

Hehe. You have to be explicit. When you connect a cable to *unpowered*
equipment and it starts to melt, or at least becomes too warm to hold in
your hand. Such as connecting the antenna BNC to an unpowered rig.

I once found a place in a factory where you could run 'emergency lighting'
in the form of 12v bulbs connected between earth ground and neutral. The
lights would get very bright when large motors would turn on and off ;-).
There was nothing wrong with the grounding (under 0.3 ohms). There was
something 'wrong' with the currents in that installation (kAs). Jolts from
equipment casings in the same room, running off different circuits are
very common (e.g. one segment on ups and one not).

Maybe this could be a new way to legally use some wasted power. Eg power
safety equipment and some led emergency lights (with small backup NiCds
also trickel charged from the ground potential) off ground potentials.

Peter

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