I was at a home last week where the customer showed me what happens when her she turns on her 4" LED lights. These were bulbs that were installed into existing recessed fixtures. If she turns the switch on and off several times, they usually work and stop flickering, but it was drastic. 

You can see a short video we took on Elm Energy Group's Facebook page....here....

Any suggestions or comments are appreciated! She has had a number of electricians look at it and they have had no suggestions or clues as to why this was occurring. I am confident someone in this online community has experienced this and will have input. I will be eagerly awaiting some responses!

Best regards,
Jamie Kaye

Tags: LED, flickering, lights

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Looks to me like a bad dimmer switch.  Is it a dimmer?  Did you try replacing it?

Maybe a CL dimmer switch is needed?

I have a couple of LED light bulbs that sometimes flash, but not in unison on the same fixture or line like you are seeing.

I would agree- most likely the dimmer. Older dimmers are problematic as well as cheap ones that do not filter the voltage.   To confirm, try placing the bulb in a switched outlet to see what happens.

I to have experienced this when I installed LED lights in my remote controlled ceiling fan. It does not happen with any other light box with a switch only assembly. What's baffling me is I have two different LED manufacturer's product and one with a single LED light chip does not flicker. This version is designed for the photography industry while the flickering one is a name brand off the shelf version from Home Depot. I do know it's definitely not a sensor problem with my equipment or the results would be the same with the LED lights. I should also note this happens with different brands of fluorescent spiral bulbs to. True blue light versus soft white light.

I think this phenomenon is related to the remote control assembly. 

The problem that i have is in a fan as well. I believe it is just one bulb that goes off and on on occasions. I am pretty sure I have seen it in one bulb on another fan as well. I bought the bulbs at Costco.

Your problem is indeed the built-in dimmer electronics in the fan that allow a gradual brightening of the bulbs and will only work with incandescent lights. CFL's us an electronic ballast and LED's have a built-in power supply that converts the AC voltage to DC. Low end dimmers are simply diodes that take the 115v AC and do a partial conversion which causes CFL/LED failure. Newer Lutron dimmers are designed specifically for both CFL and LED lighting.

Tim & Richard,

Are the light fixtures in your ceiling fans rated for use with LEDs & CFLs?

If not, there could be the problem.



The fan came with CFL in the fixture/box. So, I assume it is "rated" for CFL's. I did not know there was a rating or qualification for use with CFL's of LED's. I have both lights throughout my house, which was built 9 years ago, before LED lights were even available and CFL's were not wide spread. I don't have this problem any where else in the house.

It probably is the dimmer.  

Dimmers generally operate by turning on X amount of time after the zero crossing of AC line voltage.  For full bright the X is equivalent to immediately.  For dimmed, it may be just before the line voltage would cross zero again.  

LED's and CFL's have AC to DC power supplies inside of them that expect power to be on for a known amount of  cycle.  They handle the dimming problem by adding enough storage in the lightbulb power supply to make it a full cycle,  then they add additional circuitry to watch when the zero crossings of the line voltage is done.  Finally the dimmable LED and CFL's then translate that "dim" signal into either reduce power for the bulb, or a reduced "duty cycle" for the LED driver.   Older dimmers expect resistance bulbs.  Some older dimmers are two wire devices without a neutral.  If the dimmer is old,  or not designed to operated with LED's and CFL's, the dimmer itself will do strange things.  The light bulb responds to a dimmer acting strangely by also doing strange things... and you see flashing.

A simple test can be to replace one or two light bulbs with old incandescent lights and see if the throbbing goes away - even for the remaining LED's and CFL's.  If the problem stops, than look at the dimmer as being not compatible.  If the problem continues - the LED's are probably not dimmable.

If the problem goes away with an incandescent lightbulb on the string, that may mean that the old dimmer does not have a neutral, some of the old X-10 and home automation dimmers did not include neutrals.. LED's drive those devices nuts.  Nearly all modern dimmers and those designed for home automation systems now use neutrals.

Dennis, do you mind if I print this out and keep it in my "Binder of Good Explanations"?

Thank you for providing what would earn my vote for "best answer"!

I had a similar problem. The LEDs are on a three way lutron dimmer. I would turn them on, LEDs would flicker just once, more like a blink, then they would work fine. The problem has now corrected itself, Dimmer seems to work fine. I'm just glad it is my house and not a customer an hour away,



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