Dave (from the UK) wrote:
> Voltages induced by ground loops will be very small - sufficient
> to causes a buzz in audio systems, but not to be felt by hand.

They definitely can be felt by hand!

I've felt it myself when I wanted to connect to Thinwire ethernet
segments together in. About 50 meters on each end, stretched across a
building, run through a cable conduit where also 220V cables were
installed. Each segment was grounded at the other end. Me in the middle
holding both metal BNC connectors.

Also, the stories about musician getting electric shocks when their
guitar amp was grounded at another outlet as the microphone system, are
true.

The induced voltages can be quite high, when measured with a volt-meter
with a high internal resistance (100V is no exception, obviously at 50
or 60 Hz), but the current can't get much higher than a few microamperes
when shorted over a human body. Just enough to give you a scare, not
enough so you can't drop the cables (or microphone).

--
Alex.