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fluorescent light won't turn on in damp humid weather

Posted by fletchb (My Page) on
Sat, Jan 27, 07 at 20:03

First I wanted to thank those who were giving me advice around thanksgiving on finding a neutral. I had just bought my first house and was installing automation light switches and ran into trouble on a circuit that had 3 switches to control the overhead light/fan. To keep it short, over the Christmas holidays I had time off so I went at it again and found a white wire that had never been hooked into the bundle on the switch box closest load side. As soon as I put it in the bundle my middle switch (the 4 way) had a working neutral and I was able to get everything working. Still not sure why it couldnt get a neutral from the line side switchbox, but it's working perfect so I am not going to fret over it.

Anyway, I have an overhead 2 bulb fluorescent light in my carport that seems to have a problem in certain weather. Right now it is cold damp and humid outside and it took about 30 min to light up. Sometimes it takes less, sometimes it won't start working again till the next day.
Any idea what causes this? Can it be fixed or should I just replace it? I am about to convert the carport to a real garage but it will be a very slow process so the dampness it going to be around for awhile.

Thanks Fletch

Follow-Up Postings:

RE: fluorescent light won't turn on in damp humid weather

Change the fixture to one with electronic ballast and T8 bulbs. Your problems should go away (assuming you have a good ground at the fixture).

RE: fluorescent light won't turn on in damp humid weather

Your flourescent is working properly you do not not have a cold weather ballast (expensive) fixture . Easiest thing is live with it until warm weather comes . If you need light in your garage in the mean time use a regular light. Otherwise follow the instructions on the previous reply i is about a high energy (cold weather ballast and bulbs) new fixture.

RE: fluorescent light won't turn on in damp humid weather

Thanks guys,
I am going to see if I can find any T8's at the local hd/lowes this afternoon. Online shows only 1 at lowes and none at hd (all t12's) so I am guessing t8's are fairly new.


RE: fluorescent light won't turn on in damp humid weather

I am guessing t8's are fairly new.

Not really. They cost more because they aren't produced in as large a quantity as your basic cool white T12s. Also they (usually) work only with electronic ballasts, which are common in commercial settings but still somewhat rare in homes.

To be clear, just replacing your T12 lamps with T8s won't work. YOu also need a cold weather electronic ballast for the fixture. Many of the E-ballasts not rated for cold weather operation DO work well in cold weather, but don't bet on it, get one that's meant for cold weather.

My experience is that electronic ballasts rated to operate down to 0 deg F or lower don't cost much more than those that aren't, but that probably depends on where you buy them.

I just remembered, one thing you can try without replacing fixture, ballast, or lamps, is getting those clear polycarbonate protective sleeves for the lamps. They keep a bit of the heat in, so the lamps warm up faster. No guarantees, but they might help.

RE: fluorescent light won't turn on in damp humid weather

Thanks guys,
Found the above recommended at Lowes: Coldweather 0 degree,electronic ballast and uses t8's (only). For $40 it's worth it just to change out everything. Only worry is the box mentions it's cold weather ability but says nothing about it's humid weather ability. Guess I will find out soon.

They had a model very similar only it was the "residential" version that could use t8 or t12. It produced more noise so I went with the "commercial" version because of my home automation.


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