Flickering recessed led lights.

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Kadep

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Ok first of all I'm new to this forum and want to say thank you for any help in advance.

I have a customer who has a new home that we just finished trimming out. In the master bedroom there are four 6" recessed cans with utilitech led trims and a ceiling fan. When the cans are turned off and you turn the switch on or off to the ceiling fan all the cans flicker one time. If you pull the chain to start the fan or have the fan turned off via the chain the lights won't flicker when the switch is flipped. This room is on a 20 amp circuit protected by a afci breaker. I have taken the fan out of the circuit and wired in a pigtail with a incandescent bulb and that eliminates the flicker. I feel like I'm getting some fly back from the fan and asked the homeowner to pick up a new one. But I want to have some other options in case the new fan doesn't solve the issue that's why I've come to this forum. What else could possibly be going on and what other options do I have maybe a emi filter?
 
Kadep said:
Ok first of all I'm new to this forum and want to say thank you for any help in advance.

I have a customer who has a new home that we just finished trimming out. In the master bedroom there are four 6" recessed cans with utilitech led trims and a ceiling fan. When the cans are turned off and you turn the switch on or off to the ceiling fan all the cans flicker one time. If you pull the chain to start the fan or have the fan turned off via the chain the lights won't flicker when the switch is flipped. This room is on a 20 amp circuit protected by a afci breaker. I have taken the fan out of the circuit and wired in a pigtail with a incandescent bulb and that eliminates the flicker. I feel like I'm getting some fly back from the fan and asked the homeowner to pick up a new one. But I want to have some other options in case the new fan doesn't solve the issue that's why I've come to this forum. What else could possibly be going on and what other options do I have maybe a emi filter?
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Are the cans on a dimmer?

Also, Utilitech is junk IMO!:happyyes:

Welcome to the forum!:thumbsup:
 
160509-2133 EDT

Kadep:

Changing the fan to another identical unit probably won't change anythimg. You are probably getting an inductive kick on turn-off. The difference between the pull chain on the fan and the wall switch is probably cable length (capacitance and inductance) between the switching point and the LEDs.

For my explaination to work there has to be a large enough voltage transient to jump the gap in the off state switch to the LEDs, or other coupling between parallel cables that connect to the fan and lights.

An MOV or filter at the fan might solve the problem.

Whenever something else is affected by the turn off of an inductive load it is likely the result of an inductive kick from the inductor. Changing from one inductor to another isn't like to change much. What is needed is something to slowdown the transient (capacitor, resistor, or filter), or limit its peak value (an MOV etc.).

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170301-0837 EST

lowlandman:

My suggestion is as close to the inductive source as is reasonable. But experiment first and determine what will solve the problem. You want to clamp the voltage (MOV), or filter as close to the source of the transient as possible.

An MOV does not limit rate of rise of voltage, it is simply a soft clamping device. When clamping it absorbs energy. Too much energy and they explode, and therefore they need to be sized for expected energy, and should be safely enclosed.

A filter does not limit voltage but beyond the filter location stretches the waveform out over a longer time period, and thus reduces peak voltage for given input, and spreads the energy out over a lower frequency range. A filter may not reduce energy much, but make it less objectionable.

Try to get a response from the NEC guys as to a suitable MOV or other filter device and how to mount it.

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Perfectly timed post. I have an acquaintance who installed led lights in his basement and flicker when switched on, no dimmer. I will have to look into it and learning about transient voltages due to inductance/capacitance and possible remedies is welcomed knowledge. What do you mean by NEC guys though, thanks.
 
If the OP had followed up with a resolution, we might have a solution in that particular case. if I had to take a wag, I'd say something is wonky in the switch since operating the fan via its pull chains doesnt create the same problem.

Ozymandias, NEC is National Electrical Code.
 
MOV is a sacrificial device that will eventually short out. Buying an electronic component and sticking it in a box is not a good idea.
Many household and builder grade LED luminaires are using a Chinese engineered LED ballast which often have quirks and undesirable symptoms.
 
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