On 5/1/2012 11:01 AM, Mike Easter wrote:
dpb wrote:
....

I still expect the most likely is the ground isn't what you think it
is (as for how good or the reflector(s) aren't grounded or close
enough to the tube in the bad one).

This is the same ground, big fat ground with the power, which is
securely 'bolted' with a nut onto the fixture that has been working on
the fixture for 15 years. We would have to imagine that something has
'gone wrong' with the ground wire's grounding condition. I don't even
know how to test that.
....

It's not hard to conceive of the ground connection having developed some
corrosion at the fixture end particularly in a garage or even a
connection at the outlet where the fixtures are wired/plugged in.

Also, the ballast must make good contact for grounding as well. I'd try
a little emery cloth to shine up the contacts and check all connections
for being bright/tight first.

Are you sure you have the proper tube designations?

Also, it's possible w/ time the lamp contacts are dirty/loose and/or
have some corrosion as well.

Have you checked the actual supply voltage to be sure there isn't
something wrong w/ the supply--perhaps there's a loose or
high-resistance connection in the circuit itself.

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