5 Feb
2011
5 Feb
'11
1:29 p.m.
On electronic (i.e. personal computer) gear, I
wonder if the role of
the ever-present ground wire isn't more for RF noise than actual
safety protection.
Possibly. Althoguh a lot of computer equipment is metal-cased and
certainly wouldn't meet the requirements for double insulation. One
consern would be the mains filter. With no ground wire the casing would
flaot at half mains voltage due to a capacitive voltage divider formed
from the capacitors from the power-carrying wires to the case. Yes, the
source impedance would be quite high, but enough to give you a tingle.
Worse than that, if you connect the machine ta an earthed device and if
the logic ground wire is defective you are most likely to end up zapping
driver and receiver ICs. This was, I am told, a problem with some Acorn
Econet installations...