fluorescent lights in attic

[scook56]

John120/240,

Hang grandmas picture in the bedroom, look for the gold coins

[hurk27]

I just looked up a Sylvania electronic ballast and they say the max case temp is 70C. I think that suggests normal attic temps should not be an issue.

The attic temps will be well below 70C allowing the ballast case temp to remain under 70C

that might be true for a ballast that can dissipate the heat it creates within its self, but heat is an additive and any heat produced by the ballast including the lamps will add to the ambient temperature to cause a much higher ballast temp, we see this with transformers, one of the problems I can see is in most fixtures the ballast is inside of a metal can (the fixture housing) this will add to the temperature rise of the ballast as it will not be able to dissipate as much heat as it would if it was out in the open, add this to the ambient of the attic and you can have temperatures exceeding the rating of the ballast.

Not all attics will be well ventalated, I have been in some with dark colored roofs that were over 140° F and some even higher, while we hope this is not always the case, it is out there.

In the can lights I mention above we found that putting the box's around the cans did not reduce the heat but the direct opposite happened, it cause containment of the heat and Even more from the lamps, when we took IR readings we found we were getting 60° to 75° C readings on the ballast cases, the original ballast were 40° C rated which we found 60° C rated one we replaced them with which improved the failure rate but didn't eliminate the problem, it wasn't until we found 90° C rated ballast from Universal that we stopped having problems.

Have not had a call back since.

[iwire]

that might be true for a ballast that can dissipate the heat it creates within its self, but heat is an additive and any heat produced by the ballast including the lamps will add to the ambient temperature to cause a much higher ballast temp, we see this with transformers, one of the problems I can see is in most fixtures the ballast is inside of a metal can (the fixture housing) this will add to the temperature rise of the ballast as it will not be able to dissipate as much heat as it would if it was out in the open, add this to the ambient of the attic and you can have temperatures exceeding the rating of the ballast.

Wow,

I fully understand heat, I have also handled many electronic ballasts and they have only been warm, not hot.

So if the ballast only gets a bit over room temp normally it is not going to overheat at 120 f in an attic. The fixture it is screwed to works as a heat sink.

[broadgage]

If the attic is only used for seasonal storage or similar, with the lights used only for at most a few dozen hours a year, then I would go with either incandescents or any standard type of flourescent.

The extra energy cost of incandescent is of little importance for the limited operating hours.

The use of flourescents in a higher than intended temperature will shorten the life of the ballasts, but they should be fine if only used for limited hours.

[Cleveland Apprentice]

Thanks for all the replies! I already installed incandescents.

[Electric-Light]

An ambient temperature that is hazardous to ballast will also have dramatic detrimental effect on lamps. The lamps no longer produce design output that they do at room temperature.

Those 25W Krypton filled supersaver T8s and T5s behave about the same at higher temperatures.
For extreme hotness, T5 amalgam type lamps are preferred.

[jmellc]

Have a small industrial plant I have done work at for about 25 years. There are fluorescent lights in an attic space - biggest problem we have had is vibration in areas near vibration producing machinery. You go up there to do some work and light is not working, over 90 % of the time a lamp has just vibrated loose and putting it back solves the problem. They are T12 with magnetic ballast BTW.

I did some work in a building with vibration issues from heavy machinery. I tried rubber washers or vinyl strips between mounting hardware. That helped a lot in some cases.