CFL turning itself off -- wattage related?
February 22, 2018 7:37 AM   Subscribe

My replacement CFL bulb has been shutting off on its own despite seemingly compatible wattage/voltage. What gives? (Details follow.)

The recessed light over my bathroom sink had its bulb burn out recently, so I put in a new one. The old bulb was a 14W CFL, the new one a 17W one; the text inside the light fixture itself said something like several hundred watts, and the voltage I don't remember except in that it was identical across all three things. The new bulb is also slightly larger than the old one, although it seemed to screw in without trouble.

However, twice the newly installed bub has automatically shut itself off after being turned on for a while (and then worked fine again after some downtime). Although the wattage seems to be well under the limit, I'm wondering whether even a 3W increase is too much. Or, is the wattage thing a red herring? What could be causing these temporary shutdowns if not that?
posted by inconstant to Home & Garden (12 answers total)
 
Is it a bulb-bulb or a flood ? (par-38/BR40 reflector flood bulb) ? (Normal recessed uses a flood, but I think you can screw in a regular bulb as well.. ) When you say slightly larger, I'm thinking you put a new 40 in to replace a 38.

It's possible the new bulb is overheating, or is not meant for damp spaces (steam from shower ?), or is a dud bulb.
posted by k5.user at 7:43 AM on February 22, 2018 [2 favorites]


All light fixtures with standard mounts are designed to take incandescent bulbs, almost all of which would draw well over 17W. (There are 15W incandescents, but they tend to go into, like, those tiny candelabra-style mounts.) So it's almost certainly not the wattage of the new bulb that's causing problems.

I think k5.user is right: either the new bulb is not suitable for the environment (due to heat or moisture) or it's just a dud.
posted by tobascodagama at 7:47 AM on February 22, 2018 [1 favorite]


Oh, there is a fourth option, which is that the wiring in the walls or the fixture itself got damaged at some point. Is it possible there's a bathroom above you that started leaking down into your bathroom?
posted by tobascodagama at 7:49 AM on February 22, 2018 [1 favorite]


CFLs are much more heat sensitive than incandescents. Putting a CFL in an enclosed fixture will build up enough heat to cause the internal electronics to shutdown. The wattage numbers in the fixture don't really apply here, since CFLs draw far fewer watts than a traditional incandescent. Get some lower wattage CFLs, or switch to an LED bulb.
posted by cosmicbandito at 7:51 AM on February 22, 2018 [7 favorites]


Is it a bulb-bulb or a flood ? (par-38/BR40 reflector flood bulb) ?
Both the old bulb and the new bulb are the spiral-shaped kinds, no reflecting bits, so I think that means neither of them are flood.
Oh, there is a fourth option, which is that the wiring in the walls or the fixture itself got damaged at some point. Is it possible there's a bathroom above you that started leaking down into your bathroom?
Hm, I'm on the top floor, so if it was damage, it wouldn't be from someone above me leaking.
posted by inconstant at 8:04 AM on February 22, 2018


Since you mentioned it's recessed lighting, the lighting itself might have a temperature based shutoff. The recessed fixtures installed during our kitchen reno were chosen specifically for that. If there's insulation in the ceiling, I believe to be code this is needed, or you need the giant box to keep the insulation away.

I'll note that we went with LED bulbs - a bit more expensive, but significantly less wattage and thus less waste heat. Additionally, there seems to be more choices for LED bulbs if you look and you have much better color temperature to look for. We've got 6k lights in our kitchen for brilliantly crisp lighting that would permit surgery. 3500 in our family room to make it feel "cozy."
posted by nobeagle at 8:18 AM on February 22, 2018 [2 favorites]


Switch to LED regardless!

CFLs are horrible toxic waste, and they almost never reach their potential lifespan for reasons above and many others.
posted by SaltySalticid at 9:04 AM on February 22, 2018 [2 favorites]


Based on the answers so far, and your update, there's a solid chance it's a dud bulb. A replacement is like $5-10; maybe try that before tearing your hair out over potential deeper problems.
posted by Joey Buttafoucault at 10:31 AM on February 22, 2018 [2 favorites]


I vote for it's a dud. Get a replacement bulb and use this as an opportunity to switch to a warm-toned LED bulb. The LEDs have a longer life and no "warm up" time to get to full strength. The warmer toned/warm white ones give much better light that doesn't make you look like you're in a parking garage. IKEA is selling them at a great price if you have one nearby. They've come down in cost in most stores if you don't.
posted by quince at 12:15 PM on February 22, 2018 [1 favorite]


Why not just try the bulb in a different fixture? If the problem follows the bulb, the bulb is a dud. If not, the fixture may have a thermal safety cutout (many can lights do) which has drifted and become too sensitive, or (longshot crackpot theory) the bulb is simply not compatible with it due to having the "hot parts" (in this case the electronics) closer to the can compared to an incandescent.
posted by Larry David Syndrome at 6:21 PM on February 22, 2018 [1 favorite]


One thing to watch with CFLs (and LEDs for that matter) is that some of them have an orientation (UP or Down) which they must be installed in. Also as alluded above some bulbs aren't rated for enclosed fixtures if that is what you have.
posted by Mitheral at 7:31 PM on February 22, 2018 [1 favorite]


I sprang for a new LED bulb to cover all my bases (and checked the label to make sure it didn't say "no enclosed fixtures"), and it doesn't seem to be having the same issue. Thanks!
posted by inconstant at 8:32 AM on February 26, 2018


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