22 Jun
2013
22 Jun
'13
12:54 p.m.
On 06/19/2013 06:52 PM, Fred Cisin wrote:
Sure. Most mains filters have a pair of small capacitors (4.7nF is
typical) one from live to ground, the other from neutral to ground. If
the groudn wire is open they form an AC potential divider so the cahssis
floats at half mains voltage.
That may well be what is happening to the OP. But I would want to know
just why 2 mains sockets on the same banch do not have their ground
terminals soldily connected together. And I would want ot know it before
something with a much larger leakage current is plugged in. Having metal
cases becoem live is not my idea of fun.
-tony
. . . or you may be the ground.
I acquired an industrial PC some time back with a fairly high-end ATX
PSU in it (can't remember the brand, but it wasn't a consumer piece of
junk). As I touched the back of the unit, I could feel a "tingle" in my
fingers. A check with a DMM showed about 50VAC between the chassis and
neutral. At the AC socket, the reading was 0V or very close to it. The
AC cord checked out fine.
I haven't opened the PSU yet to find out what the source of the mystery
is, but I suspect that the wire going from the AC socket to chassis doesn't.
What I'm feeling is probably from the AC mains filter in the PSU.