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Discussion Starter · #1 ·
:help: Been doing a project at the church where my Sr. group meets. Installed theatrical lights using LED bulbs. Two circuits with an LED type dimmer and very light loads on each. 28 watts on one, 42 on the other. Dimmers rated for 600 watts incandescent, 150 LED.

When faded down fully, the lights still glow visibly.

What is the best way to get the dimmer to go to full blackout? They are leviton brand dimmers. Tried using a couple of 40 watt lights as a dummy load, but the lights are still on when I dim all the way to the bottom of the slider.

I guess I could put some high wattage lights on the circuit, but that would be ineligant and hot. Any other suggestions from you electricians out there?
 

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Senior group? DRT, I didn't think you were that old. OK, jokes aside, will the dimmers work with LED lights? When I worked at Lowe's, I was surprised that fluorescent lights required a special dimmer. Every day is a learning experience.
Edit- Reread the thread and noted the dimmer is for LED. My mistake....and so early in the month.
 

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Are you sure that those LED bulbs are dimmable? Lots aren't. According to what I've read about LEDs they work on 12-24 volt circuits, at least the house variety do. The drivers also convert the current to DC . The dimmer you are using must be compatible with the bulbs and drivers and there are a couple of different type dimmers but the most common one just momentarily turns the power off and on which in your case may not be having much effect on the conversion from AC to DC.
 

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Discussion Starter · #7 ·
I am sure it is the bulb that converts the power down to DC. With a DC circuit, resistance is all that's required to reduce voltage. At 14 watts, it doesn't take much capacity to cut the voltage. Seems there is a point at which the reduced voltage reaches a point where some bulbs begin to flicker, so the dimmers are designed not to go down to zero and continuously leak about 10 percent of the total power. I ordered some commercial resistor devices that promise to prevent the flickering, probably by automatically cutting off all power at the flicker point. Hopefully that will solve the problem.

Otherwise, it seems there are two ways to handle this: 1) learn to slide the dimmers down and click the off switch at that point, or 2) replace the bulbs with incandescent models, which filaments stop glowing at a certain point.

Unless, of course, someone here has a solution.
 

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Coal oil lamps. You can turn the wick down until the flame goes out. Does this help?:wink:
When I worked at Lowe's in 1999-2000, LED lighting wasn't in existence.
 

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I am sure it is the bulb that converts the power down to DC. With a DC circuit, resistance is all that's required to reduce voltage.
If it's a screw in bulb that may always be correct. String lights have external drivers and the puck style over tub light I wired recently had an external. Here is a fairly good article about LEDs and dimmers are mentioned down a ways and in the last paragraph. It might "illuminate" your problem. https://www.1000bulbs.com/pdf/understanding-led-drivers.pdf
 
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Discussion Starter · #10 ·
Thanks Charles. I tried a larger load on the dimmers and it actually raised the low-light level when the slider was all the way down! I think dimming down to black isn't going to happen, and that I will either have to switch to incandescent bulbs or just live with it by shutting off the light with the rocker switch when the dimmer slider hits bottom. I may have to replace the dimmers if I go to incandescents, but I will be able to fade to black. I have a couple of gadgets coming to try, but I think they are nothing more than what I tried with the bulb experiment today. If they don't work I'll send them back to Amazon and use the refund to get the incandescent bulbs, which might also be a tad brighter.
 

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If you could power them with a 12 volt Dc power source then a common rheostat should work but I would want one that is disconnected from the power source when at full resistance (lights off) otherwise it might get very hot. As the article I linked stated there are 3 kinds of dimmers. I just don`t know if you need to alter voltage, wattage, or both to go to black.
 

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I've got sliding dimmers and I've noticed the same problem. My fixtures have 2 to 6 LED or CFL bulbs. Some don't even go very dark at all. My sliders switch off at the bottom of the slide though (sliding motion ends with the off switch). It's just that the minimum on setting is already somewhat bright and it varies with the type/number of bulbs. All the bulbs that I'm using are rated dimmable.
 

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Discussion Starter · #14 ·
Thanks Ulrich for the suggestion. What amazes me is that the wireless dimmer I installed dims all 30 of the LED track lights completely to black. Maybe I should contact CREE, the company that makes the lights, to find out whether they have any suggestion, maybe a different dimmer brand.
 

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Is there room within the dimmer to fit a micro switch when the slider reaches the end of it's travel?
 

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Tom...when I first installed LED's and dimmers in my house I had problems...flicker, no dimming, either on or off but no dim, etc...

Then I read the packages more carefully...lights have to be dimmable LED's, the right dimmer is required. Now all my lights dim all the way to black, no flicker and switch works at any level.

I'm guessing you have already taken this care so a call to bulb and dimmer folks might just solve the issue.

Good luck...
 
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Discussion Starter · #17 ·
I went on CREE's site and found a number of data sheets. The bulbs will dim down to 5%, which isn't bad, but I have the wrong dimmer. They list compatible dimmers, so maybe I'll give it one more try and run a test with a recommended dimmer.

Hope this is a useful string for someone else. Lots of ins and outs for anyone considering dimmed LED lighting.
 

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I think that you have found the solution when you refered to the manufacturer for advice, and found that only some dimmers will provide full range dimming with the LEDs you are using.

A mains dimmer normally switches the mains to the load cycle by cycle, and varies the point in the cycle where it switches on to adjust the amount of power passing through.

Incandescent bulbs have a thermal lag as the there is an amount of metal in the filament that needs to be heated to incandescent before the filament will glow. Dimmers normally get around the delay that this produces by having a preset minimum of 5-10% of the mains cycle so the filaments remain warm but produce little to no light. Applied to LED bulbs, this will cause the issue you are having.

The packaging/instructions for the original dimmers might suggest a certain power level for incandescent bulbs and another for for LEDs, but unless they stipulate that they can achieve complete shuttoff for LEDs, they may not be suitable for your needs. In many applications, there is not an absolute need for them to dim to total darkness, and a low level of light is an advantage for safety.
 

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Discussion Starter · #19 ·
SOLUTION OK, got a reply that helped, then realized that the instructions were two sided and there seems to be a programmable minimum voltage that has to be programmed. Haven't been able to do that yet, but I think that will help. The bulbs are able to dim down to 5 percent, but the dimmer is preset much higher. Once programmed (which involves a tiny switch between CFL and LED), then set the minimum light level, then switch back to LED.

The instructions were there (in tiny print) all the time, but I didn't notice and presumed they were in another language. Duhhh. I'll probably try that tomorrow afternoon and let you guys know. The dimmer is a Leviton Decora, fyi.

One more electronic gadget to go and we'll be state of the art for AV at The Venue. Hopefully I can get the platform extended tomorrow too, but I'm going to need a helper to move the heavy sheet goods.
 

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SOLUTION OK, got a reply that helped, then realized that the instructions were two sided and there seems to be a programmable minimum voltage that has to be programmed. Haven't been able to do that yet, but I think that will help. The bulbs are able to dim down to 5 percent, but the dimmer is preset much higher. Once programmed (which involves a tiny switch between CFL and LED), then set the minimum light level, then switch back to LED.

The instructions were there (in tiny print) all the time, but I didn't notice and presumed they were in another language. Duhhh. I'll probably try that tomorrow afternoon and let you guys know. The dimmer is a Leviton Decora, fyi.

One more electronic gadget to go and we'll be state of the art for AV at The Venue. Hopefully I can get the platform extended tomorrow too, but I'm going to need a helper to move the heavy sheet goods.
I actually majored in technical theatre and did a lot of lighting, was even a theatre technician for a while (which also upped my tool / woodworking game). However back then tungsten/halogen lamps were new, haven’t been around any theatrical lighting in some time.

But, I did put some LEDs in my great room sconces and they also have the problem you describe, not only don’t they dim all the way down (mine seem more like 50%), but when all the way off there is the faintest of glows that you can only see late at night when it’s pitch black. I too have an LED compatible Leviton Decora dimmer, and am interested whether I can solve either of these issues. My dimmer also does ZWave so I can control it with the Harmony Hub that controls my home theatre equipment (and other lights, switches, and plugs). It’s possible this model doesn’t have the option you describe, but I’m interested in the solution, thanks for creating this thread!
 
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