Flourescent light affected by humidity

I'm in Colorado where the humidity is very low (most of the time). However, when we have a rainy spell and the humidity soars, I have one flourescent ceiling light which won't turn on. (Once in a while it will light up, but mostly it won't.)
It's not the wall switch. I've tried other switches.
It's got to have something to do with the humidity.
Any ideas?
DH in Denver
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Bad ballast? Is the fluorescent tube new or has some age on it? Is this one with a separate starter?
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Jim Yanik
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DH,
I had the same problem. I fixed the ground connection to cure this. Make a good connection at the fixture. Check the ground at the switch.
Dave M.
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DH in Denver wrote:

Generally it is the result of a contact(s) that are not making good connections. Look for the ground wire and the sockets that sometimes corrode a little. Try removing and replacing the lamps. It that fixes it and if the problem returns consider replacing the sockets or fixture. I find that once a socket starts giving a problem, the problem keeps coming back until it is replaced.
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Joseph E. Meehan

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Good ideas, and also good of Dave M. to suggest checking the grounding - that is a common reason for fluorescents to have trouble starting.
Grounding affects the electric field distribution within a fluorescent tube that is trying to start. Incorrect ballast connections, such as switching hot and neutral, sometimes also affects this.
Another thing to try - cleaning the tubes. A film of dirt/dust or dried up perspiration on the tube may become conductive enough in high humidity to screw up the electric field distribution within a tube that is trying to start.
- Don Klipstein ( snipped-for-privacy@misty.com)
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All true, and if that fails, it's most certainly a ballast (or starter if it's that type). Especially if the ballast is humming and it didn't used to, it needs replacement. Or, the whole ficture is sometimes just as cheap ;-( and not a lot more trouble.
Pop
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X-No-Archive: Yes
DH in Denver wrote:

If you have a multimeter, pull out all the lamps and check that two pins at each socket is getting a few volts on AC range. Make sure the contacts are in good conditions as well. If they're corroded, the sockets needs replacing.
If the lamps are dirty, wash them with Dawn and try again.
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