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February 1, 2008 8:52 AM

Why won't CFLs work in my fixture?

I live in an old apartment in Brooklyn. Recently, one of my fixtures has gone funny: it will turn on if I put an incandescent bulb in it, but it won’t turn on if I put a compact fluorescent in it. It is an overhead light in a globe. Also, the incandescent generally burns out quickly, meaning I constantly have to replace the bulb. I’ve tested the CFLs and they work fine elsewhere in the house. What could cause this problem? Is it dangerous not to get it fixed?

posted by Shebear to home & garden (9 answers total)

What kind of switch controls it? Some specialty switches, dimmers motion detectors and such, don't play nice with CFLs. Do incandescents seem to work normally (aside from the short lifespan) in this fixture? Do they flicker or seem dim?
posted by jon1270 at 8:57 AM on February 1, 2008

I have had that same problem (both the quick deaths of incandescent and non-working CFL) in old fixtures with decomposing wiring. Replacing the fixtures fixed the problem.

Probably it's not very safe - in my old rented house, one of these fixtures was the kitchen ceiling light, and when I replaced it I found that the fixture was not insulated and there was some really scary melting and charring going on up there.
posted by Lyn Never at 9:05 AM on February 1, 2008

Yeah, check for some sort of dimmer in the line. Almost all those things chop off the tops and bottoms of the sine waves, instead of merely reducing the amplitude of the wave. Fluorescent bulbs /hate/ that.
posted by cmiller at 9:16 AM on February 1, 2008

Nth on dimmers and old wiring. I just wanted to add that I am an electrical engineer and work with other electrical engineers - and I have some coworkers with modern houses that have this problem too, and neither they nor their electricians were able to figure it out. Not to discourage you, far from it, I'm just noting that there doesn't seem to be an "exact science" to solve this quite yet.
posted by MillMan at 10:07 AM on February 1, 2008

Could it be that the enlarged plastic ballast housing on the CFL is bottoming out on the edge of the socket before the tip of the bulb's base can get to the bottom of the socket?
posted by jon1270 at 10:24 AM on February 1, 2008

Not an answer, but this happens in our fridge too...
posted by Large Marge at 11:32 AM on February 1, 2008

hey everyone - um...revealing my ignorance: how would I know if it is on a dimmer? The switch right now is just an on/off.
posted by Shebear at 12:19 PM on February 1, 2008

It could also be wired incorrectly.. I would have someone qualified look at it. I'm no electrician, but if it's got something odd like hot + ground with no neutral you may have a hazard on your hands. It's relatively easy to light an incandescent bulb, but wiring issues tend to show up with fluorescents, LEDs and fans..
posted by bakertim at 12:42 PM on February 1, 2008

Yeah, check for some sort of dimmer in the line. Almost all those things chop off the tops and bottoms of the sine waves, instead of merely reducing the amplitude of the wave.

Just to be pedantic they don't cut off the tops and bottom, they turn on and off for a portion of the cycle. You can read more about it here. But, yes, florescent lights don't like that.

To the OP, you should probably have an electrician check out the wiring and socket, if you're not knowledgeable and comfortable doing so yourself.
posted by 6550 at 1:14 PM on February 1, 2008