I have an unattached garage that we wired for electricity a couple years
ago. I had a semi retired electrician consult and it was all inspected
and passed. I had three cheap fluorescent 4 foot fixtures in the
ceiling. The lighting circuit is on a 15 amp breaker and a 15 amp GFI
outlet. That's code and the inspector was fine with it.

Then last year one of the fixtures died and I replaced that setup with
six four-foot units that were more durable, and filled 'em with T8 32W,
daylight spectrum.

The light is great. Except now, after the lights are on for a while -
more than two hours, I think - if I turn them off, and then right back
on because I forgot something, the gfi trips. If I wait a few minutes it
won't trip. If I turn off two or three of the fixtures, it's usually
okay but sometimes still trips. I replaced the gfi outlet with one of
HD's "Heavy Duty" units. That lasted a little longer.

From some experimenting, I thought I had it narrowed down to one fixture
so I switched the bulbs out of that one with another, but now it seems
to be random. If three fixtures are off, the gfi doesn't trip. It's hard
to be sure because after a few minutes, the gfi doesn't trip any more.
I've had them on all day and everything's fine unless I turn them off
and then back on.

Anybody got any thoughts? I'm thinking I might have to run another wire
on another 15 amp circuit, and have two switched banks of three fixtures
each. But maybe I can get away with replacing all those fixtures. That
would cost more money that running another circuit up there, but I'm not
looking forward to crawling around running more wires and outlets and a
new switch. But maybe that's the only way.

Think it's the fixtures? Or am I just running too many fluorescents for
on gfi to handle?

Dan