I haven't been shocked from a real 400 Hertz power supply, but
public address amplifiers often-times have what's called a 70-volt
output.  It is a 600-ohm or 1000-ohm tap on the output transformer
whose purpose is to connect to long runs of wire in a building.  At
the other end, where the speakers are, one connects a transformer that
steps the impedance down to 4 or 8 ohms.  This scheme minimizes the
effect of the resistance of the wire, but the voltage can near 100 volts on that
type of line.  Anyway, I have felt that before and the best way to
describe it is that it feels kind of like the sensation you get when
your foot goes to sleep and then begins to get its feeling back when
you move it.  It kind of tickles but at the same time, feels very
unpleasant.

Martin McCormick WB5AGZ  Stillwater, OK
OSU Information Technology Division Network Operations Group