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I just got 3 dozen CFL bulbs for free, and was planning on replacing all the non-downward exposed fixture lights in my home with these bulbs. In the past I haven't even considered switching to CFL because of the light temperature, but after seeing the 2700K bulbs and barely being able to tell a difference I was sold, at least for free.

I accepted the bulbs based on word-of-mouth that they are fine in enclosed fixtures, with the caveat of a "possibly reduced lifespan". But, after scouring the internet I have found everything from "bulbs under 20W are fine" to "these bulbs are NOT to be used in enclosed fixtures".

Specifically, I have Earthbulb 13W Micro T2 bulbs. The manufacturer's website says nothing about them. Most of the fixtures I would be putting the bulbs in are standard dome lights like this.

I can deal with a shorter lifespan, at least, I'm willing to give it a try. But I am ultra-paranoid about risk of fire. So, does anyone have any better advice than I've been able to find to answer the question are CFL bulbs safe (from risk of fire) in enclosed fixtures?

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Fire hasn't been a problem, the burning stench of electronic death when they go out; however, is something I'll never get used to. The ballasts seem to be enclosed in fire resistant plastic. I've had them get kind of brown from heat buildup in unvented enclosed fixtures with very much reduced life. I'm slowly converting to LED technology for these applications. –  Fiasco Labs Sep 17 '12 at 16:54
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6 Answers

up vote 12 down vote accepted

We have had CFL's in a number of enclosed fixtures for years now. They generate comparable light for much less heat. The main thing you need to worry about with CFLs is, you can't use them on a dimmer unless that dimmer is designed for them. Other than that - less heat means even less risk of fire in my book.

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I don't know codes. But from the standpoint of dissipation of energy I can't imagine how putting something that dissipates less power as heat (most of a light bulb's power consumption ends up as heat) could be less safe than an equivalent wattage light bulb. That is, if you replace something that used to use 60W (mostly ending up as heat) with something that uses 13W, how can you be worse off?

If someone has a good reason, I stand corrected.

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Yes, they throw off less heat, but these bulbs are far more sensitive to heat. Unfortunately in a fully enclosed light fixture, the less heat they throw off is more than they can accommodate. –  Edwin Buck Sep 17 '12 at 14:49
    
The built in ballast cannot dissipate heat well and doesn't tolerate operating in an enclosure that allows heat buildup. The enclosed fixture must have airflow in order to remove the heat buildup. I've personally tested this between fixtures and CFLs last much longer in the vented ones. –  Fiasco Labs Sep 17 '12 at 16:46
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From the GE website:

Compact fluorescent light bulbs may generally be used in enclosed fixtures as long as the enclosed fixture is not recessed. Totally enclosed recessed fixtures (for example, a ceiling can light with a cover over the bulb) create temperatures that are too high to allow the use of a compact fluorescent bulb.

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+1, despite my having used CFLs in enclosed cans before... apparently GE says I'm not supposed to. I think this is the right answer. –  Matthew Sep 17 '12 at 15:46
    
And this is proven by personal experience. We have a desktop lamp with a spherical reflector that totally encloses the bulb. The metal reflector gets warm enough from the trapped hot air to be painful to the touch. It eats CFLs. –  Fiasco Labs Sep 17 '12 at 16:49
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Approximately two years ago I had a CFL in a hanging bar fixture, open at the bottom. I'm not sure how long it was in there but, the CFL bulb exploded in the fixture. The part that exploded was between the base and the glass light part. It startled all of us, but thank goodness we didn't have to deal with mercury splattered everywhere and there was no fire. So I am afraid to put CFLs anywhere they may be even slightly enclosed. What makes me so angry about buying these new bulbs is having to search to find out what type of fixtures they can safely be used in. This should be information that is listed prominently on every light bulb pack, including LEDs.

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+1 for "[the] type of fixtures they can safely be used in ... should be information that is listed prominently on every light bulb pack..." –  Adam Davis Mar 10 at 18:54
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The CFL light bulbs tend to generate less heat; however, they are much more sensitive to heat. If the excess heat cannot escape in a timely manner, eventually the electronics within the light bulb will burn out, even though the fluorescent tube will be fine. Since these are not bulbs with replaceable ballasts or starters, effectively you'll have to throw out the whole bulb.

Sometimes you get one that does well with the extra heat, but you will see reduction in advertised bulb lifespan. Don't expect these bulbs to be economical in an enclosed fixture, they'll just burn out too quickly. You might be able to improve your results with higher quality CFL bulbs.

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I've noted that CFLs used in fixtures with closed tops and sides (even if the bottom is open) have very short lifespans. 6 months to a year is all I've seen out of those. Open top fixtures (even with closed sides and bottom), haven't had to replace any of those despite running them for years. Heat appears to be a major problem in lifespan. I've not heard of any fire issues though. I suspect that it's actually less likely with CFLs, as someone else mentioned, the total consumption and heat dissipation is less than an incandescent.

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