Thanks for your reply. I will do that. Something of that sort is the only
thing that makes sense to me. Could the burn hole be invisible because it
is through the black insulation in a spot that is covered by the yellow
(#12 wire) insulation?

On Mon, 29 Jun 2009 22:01:49 -0500, wrote:

On Mon, 29 Jun 2009 22:23:15 -0400, wrote:

Sorry this is so long but I need to describe the whole thing.

After an electrical storm, one of the kitchen GFIs was tripped. Everything
was unplugged from all receptacles on the circuit. When the GFI was reset
the breaker tripped. Resetting the breaker caused the GFI to trip again.
This cycle was repeated several times.

Then it changed so that turning on the breaker caused the breaker to trip
immediately.

With the breaker off, a working ohm meter showed no connection between the
hot and the neutral or ground. So it appeared as if either AC or a higher
voltage was required to see a short & trip the breaker. (Remember this
whole thing started during a thunderstorm).

I started disconnecting the receptacles & junction boxes one at a time
trying to isolate where the problem was. I saw no damaged wires. I did
not know the order in which things were connected so I'm sure the order I
did the disconnects was not the best.

Eventually I could turn the breaker on without it tripping so I started
connecting things back one item at a time, testing after each reconnection
until everything was connected as it originally was. The problem was gone.
I tried wiggling the wires I could reach but the problem stayed fixed. That
was several weeks ago.

Now, immediately after another electrical storm the problem is back.

What is going on? In giving an answer, please keep in mind:
1. The problem has appeared twice following a severe thunderstorm
2. An ohm meter showed an open circuit but it acts shorted under 120 VAC
3. No apparent physical damage to the wires.
4. The breaker stays on with the GFI connected but nothing downstream
connected.
5. The problem went away (until the next sever thunderstorm) after
dis/re-connecting everything.

MANY MANY thanks for any help.

Probably a small burn hole in a wire insulation right where it enters
one of the boxes. When you disturbed it, you allowed a small gap to
stop the problem. I'd open every box again and use a magnifying glass
to carefully inspect every wire right where it enters the box. Of
course there could be a hole anywhere in the wire, but normally this
occurs at a bend in the wire and a lightning zap burns a hole and the
lightning goes to ground. I have seen this happen several times.