One of my lightbulbs went out a few days ago and I was replacing it today. I found to my surprise that the base was yellowing for no apparent reason.
I found this article online: http://www.montgomerynews.com/articles/2012/10/13/springford_reporter_valley_item/news/doc5075ce95acf4f692783257.txt
It mentions that CFL lightbulbs shouldn't be used in enclosed/contained fixture, or risk the hazard of fire:
CFLS cannot be used in lighting units where the base of the CFL is encased or enclosed. “The key is letting air around” the base of the CFL bulbs, Lengel said. That means track lighting, recessed lighting and any fixture that encloses the CFL bulb is not safe to have a CFL bulb in.
One sign of a near fire as a result of improper CFL use is when the base of the CFL bulb is turning brown.
Here are some images:
In the picture above, you can see the browning.
In the picture above, you can see the lightbulb information.
Finally, here is a shot (with the light turned out for contrast) of the fixture (there are two bulbs inside):
I would like to know if the lightbulb really is a fire hazard. If I was wrong in assuming that the bulb is not CFL, would it be a fire hazard if I did place a CFL (or two) in there?
Best Answer
A compact florescent (CFL) definitely heats up and needs to have room to dissipate that heat.
It is not nearly as hot (25–33%) as an equivalently bright incandescent, but the radiation pattern is different too. An incandescent has most of its heat coming out the bulb with only a small proportion from near the narrow base. A CFL has electronics in its base and those are responsible for a good amount of the bulb's heat.
The different heat pattern would explain why an enclosed base of a CFL would get crispy hot. If that were combined with stagnant air and warm ambient temperatures then yes, it could be a fire hazard.
However, your pictured light fixture probably does not confine the bulb's bases and was made for—what? 225 watts of incandescents? It should be fine for three 40 watt CFLs.
Do this experiment: fill it full of CFLs at or above the wattage you'd want to run. Close the cover and turn it on for at least 20 minutes. Take the cover off and feel inside. If anything is too hot to touch (120 °F/ 50 °C or greater), then it probably is not safe. If parts are warm to the touch but not verging on painful, it is most likely fine.
LED bulbs would be completely safe.