Flicker: Is it the LED Light, the dimmer, or both?

[Linwood]

I confess up front I have done little to diagnose this yet... 
 
I have switched most house lights to LED.  I always buy dimmable LED's, often from Home Depot or Lowes and whatever they have that looks reputable and on sale, so a variety of brands (Feit, Cree, Ecosmart, GE). Almost all are spotlight/PAR types in cans.
 
I always buy LED compatible dimmers, mostly Lutron, last was Legrand trying to see if it is better (in this regard not).
 
I also have a couple of UPB dimmers driving LED lights, but all conventional bulb replacements.
 
Most of the normal dimmers have a spot where they flicker horribly.  Some are at the low point, and I adjust its cutoff above it.  Some will just randomly start flickering after working fine for hours, then after a few minutes quit.
 
The UPB have never flickered - luck, type of bulb, better dimmer, I have no idea.
 
What I should probably do is start swapping dimmers around and see what combinations work and do not, but hoping for a bit of insight here first....
 
Giving that I am buying lights ostensibly dimmable, and dimmers ostensibly for LED's, is there a most likely culprit? 
 
If I got better dimmers (like... ?) is that the most likely fix? 
 
Or is it because I am buying bad bulbs? 
 
Or is the state of the art one of "check each dimmer's list against each bulb type and buy only that".  Given the rate of change it is actually hard to FIND the bulbs that work with any given dimmer per the manufacturer.
 
Any general advice of the best path?   I would even use this as an excuse to replace a lot of switches with UPB ones if that would actually solve my problem.
 
Thanks in advance, 
 
Linwood
 
 
 

 

[ano]

The problem of LED light flicker has to do with money, of course. Basically LEDs are current based devices that run at very low voltages, at least compared to a 120V powerline. For this reason 120V has to be reduced to a low current for the LED bulb to operate on. That part is easy, where it gets tricky is bulbs have to decode how dimmers work to covert that to dimmed LED lighting. This is where it gets interesting. There are only so many ways for LED bulbs to be dimmed buy "decoding" how the dimmer tells them to dim, and most of these methods are patented. So if a LED bulb maker wants to dim his bulb by "reading" a dimmer, he most likely has to license the method from someone else, or create his own way or buy chips from another company. For example, read this article...
https://blogs.duanemorris.com/greenip/2018/04/20/federal-circuit-upholds-validity-of-philips-patent-on-dimmable-leds/
 
Anyway, bulbs flicker because their manufacturers are too cheap to license the dimmer "decoding" technology from the companies that have patented it.
 
You could try this:
https://www.amazon.com/PCS-Load-Resistor-Lighting-ILR-10K/dp/B01ES0AYU8
 
PCS sells this 10K resistor it says reduces flicker. You could find your own 10K resistor (2+ watts) if your careful. Otherwise its just trial and error. Or if you have a bulb that needs to be often dimmed very low, just skip the LED bulbs as the difference in electricity won't be great anyway.
 
You can also add one incandescent bulb along with your LED bulbs on each circuit. That usually helps.

 

[Linwood]

Never realized it was basically lack of load that is an issue?   I can try that. 
 
But to the original question - it sounds like you are saying the most likely culprit (if both are labeled as compatible) is likely the bulb? 
 
So continuing to change dimmers is not as likely to yield good results as changing bulbs? 

 

[ano]

Never realized it was basically lack of load that is an issue?   I can try that. 
 
But to the original question - it sounds like you are saying the most likely culprit (if both are labeled as compatible) is likely the bulb? 
 
So continuing to change dimmers is not as likely to yield good results as changing bulbs? 

120V light dimmers have been out as long as electricity, and they haven't changed a whole lot. They basically chop the AC sinewave to only allow part of it to pass.  There is an exception, and they are usually called "low voltage dimmers" designed to dim low-voltage transformer light. They are usually limited to 300W and cost 3 times the price but they "might" work better.
 
As for dimmers, some new ones are supposedly designed for LED lights, but its trial-and-error again.  Leviton/HAI makes an UPB "LED dimmer" and I bought lots for my house, but the funny thing is, they seem to flicker MORE than their plain dimmer. Go figure. 
 
The real solution is one that doesn't really exist yet. Create a dimmer that does chop the AC sinewave at all, but instead sends a coded signal to the bulb telling it to the level it should dim, then create LED bulbs that receive this signal, and dim to that level flicker-free.  But, the problem is, it doesn't exist yet.
 
So until then, just find a combination of dimmer and bulb that works for you and stick to it.

 

[neillt]

If you are using Lutron dimmers, you can go to their LED compatibility tool site and see what has been tested and works.   I have RadioRA2 dimmers, and purchased the exact model bulbs listed on the Lutron LED tool, and can dim down to 1% with no flicker or issues.  After seeing the results, even the contractors working on my remodel understood why I was being such a needy bitch about getting the very exact model number or lamp instead of the sale du jour down at the electrical supply house.  A lot of them never knew Lutron had such an extensive testing lab with the results all online.   So, you already purchased excellent dimmers (even if they are not RA2), now you just need to pair them with bulbs that dont' suck.   http://www.lutron.com/en-US/Pages/LEDCompatibilityTool/Compatibility.aspx   If you get stumped using it, just shout.