Need fix for LED flicker, add a resistor?

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mark32

mark32

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Currently in NJ
So I'm finishing up on my buddy's basement, where I've installed over 30 integrated LED recessed trims located in seven different areas. Each area/section is controlled by a dimmer, some are SP, some are on 3ways. After they were all operational, we noticed two of the seven sections flicker when a dimmer from another secton is turned on. They will continue to flicker until one of the dimmers is adjusted either up or down. There maybe a pattern to this but it's too early to tell for sure. I've read that one can install a resistor in the effected section of lights, but how? The components are: Feit brand LEDs, dimmers are Leviton's DSL06, housings are Halo's H750icat, these have no socket, just a plug for the LED trim to attach to. Anyone remedy such a problem like this before? These LED's and dimmers play nicely otherwise.
 
161115-1120 EST

Try a 100 W incandescent bulb in parallel with the load side of a dimmer that has the flashing LEDs.

Or for a circuit with the flashing LEDs change the dimmer to a Lutron CL dimmer. This dimmer is still a two wire dimmer but has some good characteristics. It seems to work well with some CREE dimmable LEDs. But it is still a two wire dimmer and has a strange output waveform on a CREE LED. The EGC (green wire) on this dimmer is not connected to the electronics in the dimmer.

Or get a three wire dimmer that requires a neutral connection. In the past these were used for dimming a magnetic ballasted fluorescent lamp. Can't give you a part number. This kind of dimmer makes use of neutral to provide power to the dimmer electronics independent of any load. Works well with no load at all. Nice output waveform on a single CREE 9.5 W LED.

I am not impressed with Feit bulbs, but their reliability (not having component failure) seems better than CREE based on my very limited usage.

A two wire dimmer requires current thru the load to power the electronics in the dimmer. With non-incandescent loads the two wire dimmer can not always operate correctly. A three wire dimmer (one that requires neutral) is not dependent upon its load for power and correct operation.

My definition of a two wire or three wire dimmer does not relate to the actual number of wires, but rather to the function of the dimmer.

A two wire dimmer uses only the serial connection thru the load for power to the electronics. Neither a ground or neutral wire has any function in this type of dimmer. Thus, the dimmer load can have a considerable effect on dimmer operation.

A three wire dimmer uses either the ground wire or a neutral wire in combination with the dimmer hot input wire to provide power for the electronics.

If none of these solve the problem, then we have to ask other questions.

.
 
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Thanks Gar,

I like the idea of a dimmer that requires a neutral, I'll look into that. I just got off the phone with Leviton, they wanted to do some troubleshooting with me but I'm not on that jobsite, perhaps I'll give them a ring the next time I'm there.
 
If your supply house sold you an electronic dimmer try using one that dims regular incandescent bulbs. I had the same "disco" situation a few months ago and that worked for me.
 
goldstar said:
If your supply house sold you an electronic dimmer try using one that dims regular incandescent bulbs. I had the same "disco" situation a few months ago and that worked for me.
Click to expand...

Wow, never would have thought of that one. I guess I'll go over there with a bunch of dimmers and see what happens. To go back to what you said about the ELV dimmers not helping my situation. What if they had a neutral connection?
 
mark32 said:
Wow, never would have thought of that one. I guess I'll go over there with a bunch of dimmers and see what happens. To go back to what you said about the ELV dimmers not helping my situation. What if they had a neutral connection?
Click to expand...
The don't remember having neutrals with the ones I used. I think they were Diva 3-way dimmers if I remember correctly.
 
161115-2208 EST

mark32:

I don't know what the preoblem is, and my previous comments were to point you in some directions to try based on some very limited experience.

I am quite impressed with the Lutron CL even though it is a two wire dimmer.

In my home I have had two GE Triac dimmers made in 1965 and put into use in 1966. These have survived any lightning or power interruptions over the last 50 years. Other electronic equipment has not lasted that long. I liked the GE dimmers. Level was rotation of a knob, and on-off was by push-push of the knob. But I have always disliked the functionality with respect to setpoint stability, varies with load, and at low dimmer setting levels loss of line power causes failure to restart dimming after power restoration, necessary to set to higher level to restart. This dimmer was of an early design from shortly after the invention of the Triac.

Recently I bought a lutron CL thinking it might be a three wire dimmer, but it is not. But on bench testing the CL I was surprised at how well it functioned with various loads. And it did not have the restart problem at low dimming levels. In this respect it performed like a three wire dimmer. I bought another CL and replaced one of my original GE dimmers. This controls incandescent bulbs in a foyer. Now my loss of power problem is solved, and loading variations do not change the dimming level. Lutron appears to have done a very good engineering job on a two wire dimmer.

Your problem as described in the first post implies that line noise generated by some other dimmer will cause the combination of some dimmer and its LED loads to oscillate. My suggestion of trying the CL is based on my experience that it seems to have a more stable setpoint. The CLs fall in the $25 range as compared to possdibly $50 to $60 for a three wire. The one three wire I have was bought many years ago and was $60 then.

It is trial and error to look for a solution. An input filter to your present dimmer might work, but it could make the problem worse.

A three wire dimmer's operation is not sensitive to its load for the most part. Therefore my guess is that it might have the greatest chance of solving the problem.

My suggestions are based on a logical path from my experience, not just hit and miss.

.
 
Thanks again Gar for your time and knowledge.

I've used those CL dimmers with success, I just wanted to give these new Leviton's a shot. I'll go back there with a bunch of CL's and see what happens, I'll post my findings.
 
1611116-2493 EST

mark32:

Just one CL. Don't change more than one dimmer. The dimmer to change is one that dims a circuit on which the LEDs flash. The goal is to see if a CL is less likely to be adversely affected by noise put out by other dimmers. Most dimmers are going to put out much the same kind of noise. A phase shift dimmer creates a fast switching transient. Some may be different to the extent that they have internal filtering.

If a CL dimmer does not solve the problem, then find a three wire dimmer and test it in the same location.

Also do the 100 W incandescent lamp added to the oscillating LED circuit as another bulb on the circuit before trying anything else.

.
 
mark32 said:
Thanks gold and Bob. Bob, the trims are dimmable and they dim quite nicely, I might add, with this Leviton dimmer.
Click to expand...

Cool, I am just trying to point that this:

dimmable and they dim quite nicely
Click to expand...

Can be mutually exclusive, an LED may 'dim quite nicely' and still not be designed / approved for use with any dimmer.

That may not be the case for these LEDs but it is a possibility with some LEDs. :)
 
gar said:
1611116-2493 EST

mark32:

Just one CL. Don't change more than one dimmer. The dimmer to change is one that dims a circuit on which the LEDs flash. The goal is to see if a CL is less likely to be adversely affected by noise put out by other dimmers. Most dimmers are going to put out much the same kind of noise. A phase shift dimmer creates a fast switching transient. Some may be different to the extent that they have internal filtering.

If a CL dimmer does not solve the problem, then find a three wire dimmer and test it in the same location.

Also do the 100 W incandescent lamp added to the oscillating LED circuit as another bulb on the circuit before trying anything else.

.
Click to expand...

Haha, I just walked out of HD with $175 in dimmers, I was going to ask if I need to change them all or just one but I didn't.

Bob, I see your point. I figured that since they dimmed well they'd automatically be compatible. It's just that I was immediately impressed with these Leviton's because they dimmed the LED way down, very much like an incandescent. Up to this point (Using Lutron's CL's) I haven't seen that, even after setting the adjustment wheel.
 
HD has a display that shows several different LED bulbs connected to identical Lutron dimmers.
The EcoSmart brand looks like it only goes down to 75% brightness while the Cree goes down (subjectively) to 30% or less.
 
I have installed many LED fixtures. One installation used 14 LED ceiling fixtures. I have yet to find one dimmer that will always dim the LEDs I've installed; however, i have had the best luck with dimmers using a neutral, as previously suggested. Problems i've experienced include: flashing on/off, not dimming (but LEDs are marked dimmable), not being able to dim enough to satisfy client. I have found calling the tech support folks at Lutron and Leviton can be of some help.
 
161118-1340 EST

I have just run a number of tests using a standard 2 wire dimmer, a CL 2 wire dimmer, and a 3 wire dimmer. These were with no load, a 15 W incandescent, a 13 W CFL, a Sylvania LED, and a CREE LED.

The particular CREE had no flicker or flashing in any combination. The 15 W incandescent is obviously not a problem. The others have problems of various sorts. I have 20 plots I recorded.

I can provide some of the plots if of interest.

.
 
Success!! I first changed out one of the Leviton's dimmer with Lutron's CL dimmer and the flickering stop instantly on that section of lights. I'm pretty sure the flickering stopped on the other problematic sections as well, but I didn't take the time to really investigate as I wanted the dimmers within sight of this first one to match, so I ended up changing three altogether. Once this was completed, oddly, I noticed flickering in a single surface mounted Halo LED. (The one's you can mount to a standard octagon and it looks almost like a recessed light). This LED is controlled by a standard single pole switch, by the way. I purchased another surface mounted LED from another company in hopes of eliminating this flicker, but upon my last trip to the site the light never flickered, and I was there for two hours, so I left the Halo in place. Just wanted to give you guys an update. Thanks for the help!
 
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