# Ceiling fan lights dim after being turned on.



## AllanJ (Nov 24, 2007)

The electrical characteristics of the dimmer mechanism might be drifting due to heat buildup. Some heat is always generated in the dimmer and the greater the load, the warmer it gets.

If you jiggle the dimmer control, do the lights come back full strength?


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## Goodtwin (Dec 7, 2009)

If I turn the dimmer all the way down and then turn it all the way up, the bulbs will go back to their original brightness, but then suddenly dim about 30% after 5 seconds. As I was just testing this, I noticed that after turning the dimmer down and then up, the bulbs make a faint buzzing which ceases when they dim down. Also, when I turn the dimmer all the way down and leave it down, the filaments pulse on and off with a buzzing sound and I can also hear what sounds like a faint tapping sound in the dimmer switch that is synchronized with the pulsing of the filaments. Could the fan be connected improperly? I connected it just the same as the one I replaced.


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## McSteve (Dec 8, 2009)

Modern ceiling fans include a power-limiting circuit to prevent your from using more than a certain total wattage of lights. The symptom you describe is exactly what will happen if the circuit detects more than that set wattage; it will reduce the power to the bulbs by rapidly switching them on and off, faster than the human eye can see.

My guess is that bulbs you put in are actually higher wattage than the originals. Perhaps the originals were "40-watt equivalent"? I.e. they put out the same light as a 40-watt bulb but actually consume less power.

Either that or the bulbs you replaced them with are actually greater than 40 watts. For reference, I think the fan I recently installed at my house has a wattage limit of 180 watts. Anything above that will cause it to either dim, or shut off entirely.

Some weird new energy-saving law, I think.

Hope this helps.


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## kbsparky (Sep 11, 2008)

Try another dimmer, or replace it with a simple wall switch.


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## AllanJ (Nov 24, 2007)

Just for kicks, what happens if you unscrew one (or unscrew two) of the bulbs.

The way modern dimmers operate (by altering the waveform of alternating current to be different from a smooth sine wave), bulb filaments can buzz at certain brightnesses corresponding to certain waveforms.

What is the wattage rating for the dimmer switch?


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## Goodtwin (Dec 7, 2009)

I'll try unscrewing a bulb or two and see what happens and I'll also try to find out what the wattage rating is for the dimmer switch.

Might try to find another dimmer switch as was suggested just replace it with a regular switch.

I'll also check the fan specifications for wattage limitation and try replacing the bulbs with 30 watt bulbs, if they are available.

Thanks, everybody, for the suggestions.


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