On 12/3/2015 5:18 PM, John G wrote:

Many many years ago I worked as an electrician in a hospital that had an
indoor pool. Every day when the attendant turned on the Metal Halide HID
overhead lights over the pool deck, the GFCI circuit breakers would trip. I

You haven't explicitly said it (and, as I suspect they are considerably
ABOVE the pool, it might not be required?) but were teh HID's the load
that the GFCI(s) were protecting? Or, were there other GFCI circuits
and the "noise" (?) from the HID's interfering with them?

changed the breakers and tighten the connections, but the symptoms never
went away. When the circuit breakers were reset, the lights stayed on until
the pool closed when they were then intentionally shut off. The next day

So, that's the same behavior I'm reporting? I.e., first ("cold") attempt
to turn on causes breaker to trip (i.e., before it ever latches!). But,
immediately thereafter, a subsequent attempt to turn on works properly?

would bring the same symptoms. I had surmised that perhaps the high humidity
environment was causing condensation on the ballasts, but that was just a

How soon after the first failure would you reattempt? Would it seem
logical that any condensate would/could evaporate in that time?
(i.e., not liquid water, perhaps, but "dampness"?)

best guess. After a while I gave up and just made it my business to turn on
the pool lights every day.

I will return to a more structure testing "program" this weekend
(assuming nothing else rises to the top of the Honey-Do's). Among
other things, I'd like to know if, once "holding", the crcuit
will actually hold its full rated load. Or, if there is yet
another set of symptoms to add to the list...