My favorite "isolated ground" story:
During some electrical work at my wife's (government) place of employment, a worker lifted the ground for a block of offices. I do not know if there was a short or just plenty of stray voltage, but there was current on the ground at the time.
Electricity, being tricky stuff, found another path to ground in short order. My wife and her co workers notice the change as the network cards in their computers started smoking and catching fire. Apparently the only path to ground left was through the power cord to the chassis and then through the network cabling to the hub/switch. The worst part was that the IT staff determined the problem was corrected when the computers the were plugging in (and destroying one after the other) stopped catching on fire.
Moral:
Have at least one ground that works for every outlet.
SD
