LED bulb flickers when ceiling fan is switched on or off


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Old 04-29-19, 04:47 PM
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LED bulb flickers when ceiling fan is switched on or off

As my incandescent bulbs die, I've been replacing them with LED. I have several ceiling fans with the same set-up. The wall switch powers the whole unit, and the fan and light are controlled by their individual pull chains.

When the wall switch is on, and the light is on, and I pull the chain to start or stop the fan, occasionally the LED bulb in the fan will flicker at the moment the pull chain "clicks." I've also noticed this with a small air cleaner plugged into a receptacle on the same circuit as one of the fans -- turning the cleaner on or off will cause a flicker of the light on the ceiling fan.

There are no dimmers involved. Once it blinks/flickers, it's done, and the bulb is steady on. There's no constant flickering, no flickering when off, no afterglow. This was never a problem with the incandescent bulbs. The LED bulbs in question are the cheap big-box brand ones. (I have some older, name brand bulbs in some other fixtures that I might try swapping in as an experiment, but I haven't yet).

Is this just a function of a momentary voltage drop when the motor starts, combined with a cheap LED driver? Or is there potentially a bigger problem? Thanks.
 
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Old 04-29-19, 04:53 PM
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LED bulbs are instantly responsive to voltage changes while incandescent bulbs aren't. That's mostly due to the heated filament in an incandescent bulb that once heated maintains the light over short power glitches.
 
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Old 04-29-19, 07:37 PM
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So, nothing to be concerned about then?
 
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Old 04-29-19, 07:51 PM
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Nothing I'd be worried about.
 
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Old 04-29-19, 08:11 PM
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Great, thank you. ........
 
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Old 04-30-19, 04:08 PM
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Fan/light devices have the fan motor and light bulb sockets (loads) wired in parallel to a power source. This is called a circuit. While the circuit voltage is constant , the circuit current changes as loads are turned on/off which adds/removes opposition to current flow. Incandescant bulbs are resistive and have no reaction to circuit current change . However LED lamps (direct replacement for incandescants) have a internal electronic driver with impedance that reacts to circuit current changes. This reaction causes the flicker you see. LED lamps are a young industry and hopefully will improve the drivers as the product ages. Hope this helps.
 
 

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