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Bud--

wrote:
On Mon, 11 Aug 2008 01:59:41 GMT, "JohnR66" wrote:

I did have the copper ground lead connected, so it sounds like a neutral to
ground fault. That puzzeld me because I did not know GFCIs detected ground
to neutral faults, so that must be where the problem is. I will inject a
signal in the neutral ground loop and use a telephone pickup coil and
amplifier to to see I can locate the fault.
Thanks for all the help.

GFCIs look at the amount of current going out on the hot and compare
it to what comes back on the neutral via a dual would current
transformer. If you have a neutral/ground fault, some of that current
comes back on the ground and the transformer signals an imbalance..

In addition they have a second current transformer that tries to inject
a current on the neutral (or both neutral and hot). GFCIs will trip on a
downstream N-G connection with no load.

--
bud--