LED lights flicker at startup

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  #1  
Old 09-16-14, 08:14 PM
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LED lights flicker at startup

I have installed a new circuit for 6 can lights with dimmable LED. Sometimes (1 in 5) they flicker immediately after the switch is turned on. It is an LED dimmer switch up to 150W. It is at max (not dimmed). It seems more likely to occur after they have been off. They are then fine once on. All of them flicker at once (more of a quick flash).

The circuit goes from the box to a junction (where it feeds a small closet light) and then to the switch.

I replaced both the switch and the wire from the switch to the first light. I have another circuit with more of the same lights (and switches) on it. This doesn't have any issues.

Any thoughts of what this could be or how to address prior to drywalling?
 
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  #2  
Old 09-16-14, 08:38 PM
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Swap dimmers between the two circuits and see if the problem moves with the dimmer.
 
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Old 09-17-14, 05:19 AM
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Who is the manufacturer of the recessed cans and LED lights?
 
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Old 09-17-14, 06:05 AM
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CasualJoe -- The cans are manufactured by Commercial Electric (no problem with them on the other circuit). The bulbs are Philips. The switch is Levoton (or something like that). They all came from HD.

Ray -- I'll try that. I've swapped the switch out totally, so it seems unlikely to be the case, but I'll give it a shot.
 
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Old 09-17-14, 06:38 AM
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I agree test is is unlikely to change things but it eliminates one thing.
 
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Old 09-19-14, 07:01 PM
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So unfortunately changing the switch out didn't help. Could it be one of the fixtures? The lights don't flicker all in sync anymore and seem to be getting worse. The light upstream of them doesn't seem to have any issues.

Can I reuse the "quick connect" in the fixtures? If not, should I just cut off the quick connect and hook up regularly?
 
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Old 09-19-14, 07:28 PM
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I'd do that. Can't say it will help but it is need to eliminate it as a cause if nothing else. Since they all flicker I start just with the first one and then test before doing the next.
Can I reuse the "quick connect" in the fixtures?
It could be the quick connect. I'd use wire nuts.
 
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Old 09-20-14, 06:49 AM
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So of course I go to try to diagnose it this morning and I'm getting nothing. No problems. My wife said it was very bad the other day too...

Any idea what could just cause the issue on startup and only intermittently?
 
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Old 09-20-14, 09:27 AM
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What is the brand name of the LED lamp?
 
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Old 09-20-14, 09:55 AM
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Tolyn -- The bulb is Philips and the can is commercial electric.
 
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Old 09-20-14, 10:58 AM
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Sorry, I did not see post #4

While I have not had experience with that particular brand, I have had some issues with other brands with flicker (most cases caused by a dimmer), buzzing (dimmer again), and lamps not turning back on after then been turned off.

I doubt the can is at fault if they are just standard can fixtures with medium (standard) bases. I would maybe try a different brand of lamp. Also, measure the voltage at the can. It should be 120v +/-10%
 
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Old 09-20-14, 04:48 PM
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I have another circuit with more of the same lights (and switches) on it. This doesn't have any issues.
This other circuit, you have the same cans and same dimmable LED lamps and same dimmer? Yet, no problems with this other circuit? You tried swapping the dimmers and the flickering stayed with the first circuit and the other circuit was still fine?

Have you double checked all of your connections on the flickering circuit?
 
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Old 09-20-14, 05:54 PM
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Tolyn -- I'll gladly answer the questions again. I really appreciate the advice. I'll try checking the voltage.

CasualJoe --That's right. I've shaken all the cables and haven't been able to make any flickering. It only happens at startup...and then only occasionally. I wonder if it is the power the dimmer is giving for the startup...but it happens when the dimmer is at full power too...
 
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Old 09-20-14, 07:20 PM
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I've shaken all the cables and haven't been able to make any flickering.
I don't think just shaking the cables would affect the connections if they are in boxes or the fixture connection box and all cables are properly secured. Have you checked the actual connections? The problem has to be something peculiar to this one circuit as the other circuit doesn't flicker.
 
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Old 09-20-14, 08:16 PM
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I'd suggest review posts 6 and my reply in 7. I think that faulty quick connects are becoming more likely. Just wild guess the ambient temperature affects the expansion and contraction in the first quick connect and how well it connects. That seems to be bolstered by the fact the flickering stops after the light gets warmer..
 
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Old 09-21-14, 04:51 AM
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In electronics I have encountered many poor connection issues and one symptom is the initial blink causes a bit of heat which closes the gap and makes the connection, along the lines of Ray's temperature comments.
I haven't re-read the thread, but from that junction box where the closet branches out, have you watched the closet light to see if it is steady or blinks? If it stays steady while the rest blink, then it points to that connection or downstream. If my memory has me lost, sorry.

Bud
 
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Old 09-21-14, 07:28 AM
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I went through a similar exercise with a client several years ago as LED can lights were in its infancy. I was dealing direct with an engineer at the manufacturer (Cree). Struggling to recall exactly how we got to the solution. But it has to do with the dimmer and amount of energy needed to start the LED's. It causes a flash at full light and then it settles into its normal output. I believe we had 9 cans on a 3 way circuit. It even baffled my electrician. Between Cree providing replacement lights and I believe (hard to recall) we ended up using a standard dimmer, we solved the problem.

Here is some interesting reading on LED's and their drivers - Controlling LED lighting systems: introducing the LED driver - LEDs
 
  #18  
Old 09-26-14, 09:46 AM
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So I cut the quick connects off and hooked everything up the normal way. It was looking good for a while (no flicker for two days), but did it this AM. I think I'm going to sub out the bulbs for CFL or incandescent and see what happens. Any other suggestions are much appreciated -- made a lot of progress thanks to the folks here.
 
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Old 09-26-14, 10:21 AM
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I'll make this short. I reviewed the entire thread and the one thing I did not see (sorry if I missed it) was questioning the power connections to and from that junction box. The closet light may or may not respond to the flicker so can't conclude that the problem is beyond the junction. Is the closet light an incandescent, CFL, or identical LED?

Note: All 6 lights flicker, thus the cause is something they have in common. Most likely is the power to and from the junction box, or the dimmer and the common feed to all 6 cans.

If you replace those LEDs with other types of bulbs, the flicker may continue but not be apparent. Incandescent bulbs for example would not respond to a very short flicker.

In the room where the identical arrangement works just fine, are there any additional different types of lamps included?

Bud
 
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