On Wed, 02 Dec 2015 00:13:36 -0700, Don Y
wrote:

On 12/1/2015 8:00 PM, wrote:
On Tue, 01 Dec 2015 21:46:03 -0500, wrote:

On Tue, 01 Dec 2015 19:26:18 -0700, Don Y
wrote:

On 12/1/2015 7:19 PM, Don Y wrote:
The outlets in the back of the house are on a 20A GFCI.

For those who didn't connect the dots, this is a GFCI *breaker*,
not a GFCI *outlet* daisy-chained to feed the others.
Does it trip with nothing connected? If not, it's not a dauber or
anything on the main circuit. It has to be on the "load". Outdoor
lights on a GFCI can be a problem - lots of possibilities for
"leakage"

If there is absolutely nothing connected, a neutral fault will not
trip the GFCI. The slightest load will trip it tho. (it splits the
neutral current)
The other thing to remember is the faults are additive. If you are
leaking a couple ma in a couple places, it will work until the total
gets up around 5ma or so.

You're ignoring the fact that the breaker latches and HOLDS on the
"second attempt". This suggests the problem is related to the
change in load characteristics from the previous "brief lighting
event" (fraction of a second when power surged into the lamps
just before the breaker trips on the first attempt).

I'm at a loss to explain how anything else could appear and
then disappear so readily!
Unless the first application of power heated and "dried" whatever
was causing the leak. Not a very likely scenario, for sure - but
possibly just within the realm of possibility??