Flickering Lights

[WSB123]

I responded to a call where a customer's dining room chandelier was flickering. It was on a dimmer. I removed the dimmer and immediately the flickering stopped. I changed the dimmer only to have the issue continue and installed a third dimmer just to verify the issue was not a fault dimmer. The dimmers I installed were the Lutron Ariadni. By the way, I called Lutron tech support and they had not a clue - could only suggest trying a reverse phase dimmer, which I have not done, yet.
The customer had (6) dimmable LED bulbs in the fixture. While I was there he replaced them with a hodge-podge of incandescent bulbs (4) 25 watt and (2) 60 watt. The flickering was much worse with the incandescent than LED. When I removed one 60 watt the flickering stopped. Screw it back in and flickering reoccurs. I continued different configurations. When I installed (5) LED and one 60 watt incandescent the flickering stopped. I replaced one of the LED with a second 60 watt incandescent and the flickering returned. I went back to the 1 and 5 configuration and noticed that if I removed the incandescent the LEDs would flash brightly and then actually get a little brighter than they were previously. Screw it back in and the LEDs flash brightly and then get a little dimmer than when the incandescent is removed. When the dimmer is bypassed there is no flickering, nor is there any flashing or change in brightness of the LED bulbs when I do the same experiment.
I did check the neutral connections in the panel and did find that some, including this circuit was a little loose, but I do not think that this phenomenon is due to a loose neutral since the switch is the last device in the series and all of the lamps plugged into wall outlets ahead of it do not flicker at all. Besides, if it was due to a loose neutral flickering would continue regardless of whether there was a dimmer or switch. This is a single pole device.
There are numerous other dimmers in the house, although many are the older rotary dimmers, so I do not see how the flickering could be affected by changing to a reverse phase dimmer.

I thank you for any thoughts / input you may have toward this situation.

 

[ptonsparky]

Try the dimmer as suggested.

Check the LED lamp mfg as they may have a suggestion as to which type of dimmer to use.

The one one time I seriously researched, Cree had specific dimmers listed for the style of their lamp I intended to use.

 

[Buck Parrish]

Try a different brand of dimmer. Some of these things can be a pita, but you'll find the problem, just keep at it. Some times it's best to leave it and come back the next day. Which is what I presume you have done.

 

[gar]

181108-9838 EST

WSB123:

Educate yourself.

Get a Variac, each of the different dimmers you have tried, a three wire dimmer, a CREE LED, different LEDs you tried, and a single socket to do some bench tests. A scope if possible.

By a three wire dimmer I mean one that requires a neutral. This type of dimmer will work correctly with no load on its output. These are used to dim a fluorescent via a dimmable ballast. Such a ballast has a constant full voltage output that keeps the fluorescent filaments heated with very little arc flow. The variable part of the dimmer does not require current flow for the electronics to work because of the required neutral, and thus, can provide a consistent turn on time in the AC cycle, and a constant modulated voltage waveform. That means a voltage waveform relatively independent of load.

I have found some CREE bulbs to dim very well with either a variable sine wave, or with a phase shift modulated sine wave.

Play and see how different combinations work.

However, based on what you have already done there may be some other problem than just the right combination of components.

.

 

[growler]

However, based on what you have already done there may be some other problem than just the right combination of components.

.

I hate little jobs like this because it's often hard to get paid for all the time you may have to spend to solve the problem.

 

[K8MHZ]

Try a different brand of dimmer.

I second that. Especially if the flickering was there with incandescent bulbs only.

 

[K8MHZ]

I hate little jobs like this because it's often hard to get paid for all the time you may have to spend to solve the problem.

When I was doing troubleshooting all the jobs were T&M just to make sure we got our time paid for.

 

[JFletcher]

perhaps I missed it, but what happens upon installation of a standard snap switch or just wire nutting the feed and the switch leg to the chandelier in switch box together? I would also check the connections in the canopy of the chandelier.

that your problem got worse with the installation of incandescent bulbs over the LEDs, which have a higher wattage draw, seems to me to indicate that you have a loose wire problem somewhere, either in the chandelier itself or its canopy.

edited to add, you might be able to hear an arcing connection if you are close enough to it. a mechanic's stethoscope might also help you here, that way you do not have to pull the canopy or chandelier apart.

A FLIR scan might also find a hotspot of an arcing connection.

 

[K8MHZ]

perhaps I missed it, but what happens upon installation of a standard snap switch or just wire nutting the feed and the switch leg to the chandelier in switch box together? I would also check the connections in the canopy of the chandelier.

that your problem got worse with the installation of incandescent bulbs over the LEDs, which have a higher wattage draw, seems to me to indicate that you have a loose wire problem somewhere, either in the chandelier itself or its canopy.

edited to add, you might be able to hear an arcing connection if you are close enough to it. a mechanic's stethoscope might also help you here, that way you do not have to pull the canopy or chandelier apart.

I think he already did that: "I removed the dimmer and immediately the flickering stopped."

 

[JFletcher]

I think he already did that: "I removed the dimmer and immediately the flickering stopped."

: I see that now... Sometimes hard to read a wall of text. That the flickering problem got worse with six incandescents with a 160 watt load seems to me to rule out the dimmer all together and point toward a connection problem. these tend to be more prevalent in older homes where the power comes into the light box and a switch leg is rundown to the switch box. That light box is almost always overfilled, and if it ever had a ceiling mount light fixture there, the heat definitely deteriorates the connections.

Many chandeliers the candelabra base sockets are only rated for 25 watt bulbs, running them with 6 60 watt bulbs (as has probably been done once or twice in its lifespan) could have very well deteriorated its internal connections. Combined with over-tightening, the extra heat from a higher wattage bulb may have very well sacked out the center tab spring tension in the lampholders so the bulbs are not making good contact.

Troubleshooting can be maddening, however I love it as the op's methods, Gar's methods, and mine are quite different. Even if or when I am wrong, I always learn something new.

Occam's razor basically states that the simplest problem to a solution is often the correct one, and in residential electrical, a loose connection is the prime suspect, especially in tract wired houses that were wired for speed not quality.

 

[readydave8]

I hate little jobs like this because it's often hard to get paid for all the time you may have to spend to solve the problem.

me too, sometimes have to chalk extra time up to R&D and hope I learned something that will be profitable on future calls

 

[WSB123]

This is not an old house; maybe 25 years at most. This is a CL rated Lutron dimmer, of which I tried three. Two Aridani styles and one Diva. All functioned the same as I originally posted, so the odds are against it being three bad dimmers. I have not tried another brand and I am glad to do so, but I have never had an issue with Lutron before.
I ruled out a loose neutral connection because there is no flickering at all in the three lamps that are ahead of the switch location, although I did check some connection points just to take an extra step toward finding the problem. The circuit runs through the outlets and ends at the switch, so the only connection is the incoming feed and the switch leg in the actual switch box.
As I mentioned previously, I can remove dimmer the light does not flicker regardless of the type of bulbs installed. One thing I did not mention previously is that the customer tried troubleshooting this on his own before he called me. He said that he dropped the canopy on the chandelier disconnecting it and connected a pigtail to rule out an issue with the fixture. The dimmer flickered with this one bulb, as well.
When I spoke to Lutron, the only advice they could give was to try a reverse phase dimmer because it may be compatible with the transformer powering the house. I may be wrong, but I can't see how that could be an issue. EMC did not put a different padmount at this house than all the other houses in their service area. I have never seen an issue like this before.

Thank you for your assistance,
WSB123

 

[gar]

181114-0749 EST

WSB123:

Have you tried any of the experiments I suggested in post #4?

Also it would help if you paragraphed your various thoughts to get down to one variable per paragraph.

As I pointed out in #4 I have found some CREE bulbs to dim quite well with any of (1) a variable voltage sine wave provided by a Variac, or (2) the same bulb with a three wire dimmer (I previously defined this), or (3) a Lutron two wire that costs about $20 (this dimmer works better on incandescents than an ordinary two wire unit with respect to restart at low settings on loss of power and return of power).

A Variac or three wire dimmer provides a stable voltage waveform at almost any dimmer setting to most loads.

An incandescent only load provides an almost constant load with respect to time at 60 Hz at a specific brightness. However, its average resistance varies by over a 1 to 10 range from 0 to full brightness.

If you know how your components work under bench test conditions, then with those same components in the field application you can more directly test for other causes to your problem.

.

 

[RDean]

This is not an old house; maybe 25 years at most. This is a CL rated Lutron dimmer, of which I tried three. Two Aridani styles and one Diva. All functioned the same as I originally posted, so the odds are against it being three bad dimmers. I have not tried another brand and I am glad to do so, but I have never had an issue with Lutron before.
I ruled out a loose neutral connection because there is no flickering at all in the three lamps that are ahead of the switch location, although I did check some connection points just to take an extra step toward finding the problem. The circuit runs through the outlets and ends at the switch, so the only connection is the incoming feed and the switch leg in the actual switch box.
As I mentioned previously, I can remove dimmer the light does not flicker regardless of the type of bulbs installed. One thing I did not mention previously is that the customer tried troubleshooting this on his own before he called me. He said that he dropped the canopy on the chandelier disconnecting it and connected a pigtail to rule out an issue with the fixture. The dimmer flickered with this one bulb, as well.
When I spoke to Lutron, the only advice they could give was to try a reverse phase dimmer because it may be compatible with the transformer powering the house. I may be wrong, but I can't see how that could be an issue. EMC did not put a different padmount at this house than all the other houses in their service area. I have never seen an issue like this before.

Thank you for your assistance,
WSB123

I've been researching a dimming issue of a somewhat similar nature when I ran across your post. I'm curious to know if you've been able to resolve your problem?

I also wanted to jump in here and make some comments. I work for a residential lighting business in Madison Wisconsin. I've been in the industry for a little better than 30 years and, I've never been so dumbfounded by the issues that dimming LED lighting generates. During my lighting tenure, I also worked as a manufacturer's rep for Lutron lighting, and also spec'd and pedaled their product on projects for many years. Though I haven't represented or sold their product recently (read ten years), I understand Lutron's recommendation to consider a reverse phase device since, the driver itself is solid state. The driver In your case is the simple electronics located within the lamp.

In Lutron's mind, if you're dimming an electronic transformer/driver, a reverse phase dimmer is (in their estimation) the best since you're slaving a capacitive load. It has saved my hinder on may occasions particularly if they incorporated a neutral connection. The trick is, depending on the age of the home, you may or may not have the needed connection.

This may be a silly question for asking it now but; was it ever determined if the lamps were dimmable?

Best regards,
Roberto