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Flickering Lights
September 20, 2009 5:55 PM   Subscribe

I had 4 compact fluorescent bulbs (candelabra base) in a ceiling fan that I recently installed and they would flicker terribly until I replaced one with an incandescent bulb and it stopped. The fan is not on a dimmer switch. Any ideas on what is causing this and does it need to be fixed?

We have 5 other fans that are the same model and brand that were installed by an electrician over a year ago and work just fine with cfls. Do you think I need to check the wiring or just return the thing. I don't know if it matters, but the fan and light are on one switch and we use the pull chains to turn the light on and off. I read on the internet about switching one CFL out for a incandescent, which has stopped the flickering but the only explanation for the flickering was a possible dimmer switch (which we do not have). The CFLs are rated for ceiling fans.
posted by tvgraphicsguy to Home & Garden (11 answers total)
did you try a different cfl? Not withstanding a loose wire(s) I think you have solved the problem. But that is peculiar. I very much like my cfls. They do save money & the mercury risk is way over blown. (IANYE)
posted by patnok at 6:16 PM on September 20, 2009

Yes, I tried a different kind of CFL, and it also flickered.
posted by tvgraphicsguy at 6:18 PM on September 20, 2009

does it only flicker when the (motor) fan is running?
posted by SatansCabanaboy at 6:38 PM on September 20, 2009

I tried it with the fan off. It still flickers.
posted by tvgraphicsguy at 6:49 PM on September 20, 2009

Could it be that the new source of light hides the dark periods of the CFLs with its own glow?
posted by cmiller at 7:05 PM on September 20, 2009

I'd have an electrician check. See this page for some funky things that can cause this including two-way switches.

I think the reason it doesn't appear to flicker with the incandescent in the mix is just that the incandescent provides light during the "off" portion of the flicker. In other words the flicker is continuing, but you don't notice it because the continuous light from the incandescent masks it.
posted by beagle at 7:12 PM on September 20, 2009

I would guess there is something on the circuit causing interference maybe a motor of some kind(fridge,freezer etc).You should check the wiring diagram and instructions that came with it to make sure its wired properly and that your using the right lamps
posted by SatansCabanaboy at 7:15 PM on September 20, 2009

Let me see if I can explain further. They don't seem to flicker off as much as get brighter, nearly blinding at times (this may have to do with the CFLs being of the instant on variety. The non-instant on CFLs just flickered more dimly but not really on and off.) The CFLs are brighter than the incandescent, so I don't think its obscuring the flicker. Also, the flicker is pretty constant, not at any intervals and the old fan had CFLs and did not flicker.
posted by tvgraphicsguy at 7:46 PM on September 20, 2009

I've experienced similar problems with CFLs and a ceiling fan light fixture. It degraded into a non-working light fixture, which I've so far been too lazy to fix, but since the bulbs aren't the problem (no bulb now works), I assume a connection was working itself loose.
posted by IAmBroom at 8:49 PM on September 20, 2009

Sounds like something is making high voltage, low energy spikes on your power line, and the incandescent bulb present a low enough impedance to the line to attenuate them. While the load is 4x CFL, the spike is sufficient to affect them, but once you add an incandescent, your load goes up significantly, and the noise does not APPEAR to affect them, but it still may be there and the effect may be less noticeable.

You'd need an oscilloscope to look at the AC line. Otherwise, you are making assumptions based on limited observations. Your only measurement device is your eyeball and even it is deceiving. It's limited in bandwidth, only capable of seeing things that happen in a 20th of a second or slower.

If I were doing this, I'd get a 'Y' type bulb adapter, put it in one of the 4 sockets, use a bulb-to-plug adapter to access the power line at the other side of the Y adapter with some zip cord, and look at the AC on a scope under the conditions of 4 CFLs, flickering and 3 CFL+1 incandescent, not flickering. Something is different. The first order of business is observing reality. The next task is explaining what you see. The final task is altering things to achieve your desired ends.

I am admittedly a geek, and have such tools, but do not have this problem. Someone in your list of acquaintances is also probably a geek. Seek them out for help! (Do you have a ham radio uncle who might own a scope? He would love a challenge.)
posted by FauxScot at 2:21 AM on September 21, 2009 [1 favorite]

One more thing.... a similar symptom will appear sometimes if you have an illuminated light switch. These were common in the 60's, and were basically a neon bulb placed across the switch. They were on when the switch was off, to allow seeing the switch in the dark. When the switch is in the off position, they pass just enough current to allow the CF bulbs to blink on briefly... once every several seconds. An incandescent will also snub the leakage and prevent this from happening.

I only mention it in case someone else is searching this thread in the distant future, looking for the ghost in their kitchen lamp.
posted by FauxScot at 5:42 PM on September 21, 2009 [1 favorite]

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