Why are my new LED lights flickering on the dimming system?

As many of you may have found out, not all LED lamps and/or lighting fixtures are created equal.

A common problem that we run into within our industry is when a customer wants to replace their existing incandescent lamps with new highly efficient LED lamps and/or lighting fixtures.  When they change out all of their LED Lamps and/or lighting fixtures and then turn them on, they often find them flickering.

Why do they flicker?

There are many reasons why an LED lamp can flicker, but the most common cause is a lack of resistance in the lamp to allow the dimmer curve to work correctly.  This is not a new issue; it’s been around for a long time, but is becoming more “noticeable” with the major increase in LED usage.

We first saw this issue when dimmable fluorescent lamps and/or lighting fixtures became popular several years ago.  The same issue occurred, because the fluorescent lamp does not have enough resistive load between the load and neutral wires (complete circuit).

Over the years, we have done many things to try to stop that flickering issue with the fluorescent lamps and now with the LED lamps.  The biggest key is often to add resistance, but this does not always fix the problem.

Many dimming manufacturers and LED manufacturers are now working together to prevent this issue.  However, since there are so many new LED lamp manufacturers, it is hard to achieve much consistency with this endeavor.

The quickest advice I can give you at this time is try out the LED Lamps and/or fixtures on one circuit, before you order a whole lot of LED lamps.  I recommend taking a circuit with between 1-5 lamps on it to replace with the LED lamps and/or fixtures.  If the LED lamps will work on this type of circuit, then odds are high that it will work on the rest of your circuits.

What are the LED manufacturers doing to correct this issue?  As mentioned above, they are getting together with the dimming manufacturers and are working on solutions.  A simple solution is for the LED lamp manufacturers to add a resistant circuit to each lamp, which helps with the dimming process.

In addition, the dimming manufacturers are coming out with many new types of dimmers, which help to address the need for very little resistance on the dimmer by either adding resistance to the load or using different types of dimming such as forward phase or amplitude dimming.  However, if you already have dimmers, it hardly seems like a fair trade to replace your dimmers to install LED lamps and/or lighting fixtures.

We have successfully replaced many incandescent systems with new LED Lamps and have had tremendous success.

Why switch to LED lamps?  The biggest reason is the amount of energy you save by using an LED lamp which can be about a 20 times (or more) savings over an incandescent lamp or 6 times for a fluorescent lamp.

What is the advantage of LED lamps over fluorescent lamps you may ask?  LED lamps produce less heat, so that, your HVAC costs are less and the lamps are not considered hazardous materials (mercury in fluorescent lamps) and do not break nearly as easy as a fluorescent tube (go ahead, tell me you like cleaning up a broken fluorescent lamp – HazMat crew anyone?).

I predict that within 5 to 10 years the vast majority of lamps will be LED and not fluorescent.  You can either be a leader or a follower.  Yes, the prices will continue to come down and the longer you wait, the less you will have to pay for the lamps, but you still have to pay for the extra energy now.

Thanks for listening and I will try to post again in the future.  Please let us know if you would like any topics discussed.

19 Comments on “Why are my new LED lights flickering on the dimming system?

  1. How would you determine the amount of resistace load to add to prevent flickering ?

    • Hi David,

      Thank you for contacting us regarding LED Lighting; I will forward this question to a technician who will contact you shortly.

      Thank you!

  2. David,

    Good afternoon.

    Thank you for your question about the resistance levels needed for stopping LED Lights from flickering.

    Unfortunately, there is not a set amount of resistance and it will vary depending upon the type of LED Lighting fixture you are using.

    If you would please send me an e-mail at mark@goknight.com, I will then help you further on your issue.

    Thank you.

    Mark

  3. The problem is not just with the fixture, but with the dimmer. LED lights require dimmers that can handle them, sort of like the difference between analog and digital.

    • Kathy,

      Yes, dimmers can make a difference with the LED lighting fixtures, however, the drivers on the LED lighting fixtures make the BIGGEST difference in whether an LED lighting fixture will or will not dim properly.

      There are leading edge, trailing edge, and amplitude dimmers available. The most common dimmers are leading edge through SCR based diimming and are also the most tricky to use with LED lighting fixtures.

      I have used a LOT of leading edge dimmers with LED Lighting Fixtures with great success. However, I have had some LED Lighting Fixtures that have not worked well and these often times will require trailing edge or amplitude dimmers. These dimmers are much more expensive and is why they are not used as often.

      As time goes by, the LED Lighting Fixture manufacturers will perfect their drivers and more trailing and amplitude dimmers will be available in the marketplace.

      A fourth alternative is more and more LED Lighting Fixture manufacturers are using 0-10volt control wiring for the dimming of their lights. This is because the three previous models of dimming require a variable tap transformer to adapt to the power input from 0-120vac AND dim the LED Lighting Fixture.

      While the 0-10 volt LED LIghting Fixtures have constant 120vac or 277vac power to the driver and then a 0-10 volt sink control circuit. In this case, all of the dimming is actually being done at the driver and the “dimming system” is simply regulating the 0-10 volt control signal for dimming the LED Lighting Fixtures.

      Hope this helps. Please feel free to ask additional questions?

      Thank you.

      Mark

      • Mark
        Please help. I am a general contractor. I had my electrician install 160 LED 11 watt flood lights on about 20 circuits in a restaurant. We purchased the bulbs from LED Wholesaler in California. I can not find a dimmer that will dim the bulbs low enough and not flicker. Sometimes they work fine. Other times you can not stop them from flickering . I am about ready to loss my mind. Can you offer any help

        Rich
        8168206644

      • Hello Richard –

        Thank you for this inquiry. I am going to email you separately and copy Mark so he may begin working on this issue with you. He is out of town today, but I expect him in the office tomorrow. Please look for an incoming email from “stacy@knightsoundandlighting.com” Thank you!

  4. Interesting discussion,
    I have 6 LED’s on on dimmer, the dimmer works but they are flickering on Max, and when
    slightly dimmed. At 1/2 way they are stable, would it help to take out one of the LED’s
    and replace that with an incandescent ?
    Thanks
    RJ

    • Hello! We will be forwarding your question to a technician to answer. You should hear back within 24-48 hours. Thank you!

    • RJ,

      Good Evening.

      Thank you for your question about the LED lights on your dimmer.

      Yes, you can try to add an incandescent lamp into the circuit, which I believe will stabilize the situation with your lamps. Try it and see what happens.

      If that works (let’s assume it does), then the issue is probably one of two items:

      1) The LED lamps you are using are not dimming capable. They should say whether they are dimmable or not on their original packaging.

      2) If the LED lamps ARE dimmable, then more than likely, you will want to change the type of dimmer you are using to control them. I am assuming that you are using a standard wallbox dimmer. If that assumption is correct, then most wallbox dimmers are forward phase dimmers. This means that they chop off the front part of the electrical wave. This can be hard for some dimmers to control properly.

      One option is to replace the wall box dimmer with a “reverse phase” dimmer, which is cutting of the back half of the dimmer curve. This allows the electronics and transformers inside the LED lamp to work properly.

      If you are using commercial dimmers, then the same issue with forward and reverse phase dimming is quite possible. There are options here as well.

      Hopefully, I have answered your questions, but if you have additional questions, please feel free to call and/or e-mail us.

      Have a wonderful day!

      • Thank you so very much, I will explore these remedies and let you know what transpires.
        Have a great day!!!!!!
        Ron

  5. Hi,
    I am trying to dim a Osram Led strip connected with 0-10v dimmable driver.
    The dimmer in question is Legrand Zigbee 0-10v dimmer.
    When the light is at max, its stable, but once i try to dim the light the flickering starts.
    the more i flicker, the more evident the flickering starts.

    Please help me. What should i do in this case?

    • Good morning.

      Thank you for your question about dimming 0-10volt LED Osram Strips.

      Please start out by reading my blog post about the difference between Sinking and Sourcing 0-10 volt. The website link: https://knightsoundandlighting.com/2015/05/08/what-is-the-difference-between-sinking-and-sourcing-with-0-10-volt-control-systems/

      This should help to explain how your 0-10 volt LED fixtures operate. You have sinking fixtures, not source (by the way).

      Typically, flickering on a 0-10 volt LED fixture occurs when there is a grounding issue. This can be caused by either the LED lighting fixture or the LED 0-10 volt dimmer. Remember (I know you read the article above), the LED 0-10 volt dimmer is not actually dimming the light fixture, instead it is grounding the 0-10 volt leads to a certain voltage, which causes the LED 0-10 volt driver on the fixture to go to a certain light level.

      If you were close to me, this is what I would try.

      1) Test the 0-10 volt control of the lighting fixtures by disconnecting the 0-10 volt leads from the dimmer. Hold them apart, light should go to 100 percent. Hold the 0-10 volt leads together (wire nut) and the light should go to its dimmest level. If it did not OR the flickering continues, then the problem is with the fixture. Replace the fixture or check your wiring.

      2) If Item 1 tests normal, then try another 0-10 volt controller and see if you get the same result. If you don’t then the issue is with the 0-10 volt controller.

      3) If you get the same result, then the 0-10 volt LED driver on the fixture is probably a “non-isolated driver” which can cause serious issues. Please read the following document for additional information: http://www.pathwayconnect.com/images/stories/support/Pathway_Bulletin_14_9_4-1%20eDIN%201004.pdf.

      4) The final thought is heat. LED lighting fixtures do not produce heat, but their drivers and/or transformers due produce heat. Heat is generated when the lighting fixture is dimmed and typically not when the light is at full intensity. This issue can be tested with Item 1 listed above.

      Please try these recommendations and let us know if we can be of further help.

      Thank you.

      Mark Knight

  6. I’ve recently installed 3 separate sets of LED lights in my home. I’m updating my 1970’s era ranch and the LED lights are an expensive but attractive option. The problem is that all three sets flicker when dimmed. I’ve carefully selected the dimmer switches to avoid this specific issue without any success. Yesterday I split one of the sets of lights off of their existing circuit and put them on their own breaker, yet after the lights remained on for several hours they began to flicker. Any help/suggestions would be greatly appreciated. One set of lights are so bad that we cannot use them.

    • Brian,

      Good evening.

      If I am reading your post correctly, your new LED lights begin to “flicker” even if they are on just a breaker and not through a dimmer at all. Is this correct?

      If the statement above is correct, then the problem is a heat related problem. Although the LED itself does not produce any heat, there is an LED Driver and Transformer, which do produce heat. If the LED Driver becomes too hot, the LED Driver will cause the LEDs to flicker.

      Are the new LED lights in an enclosed space? If so, then the heat buildup is causing your issue and you will need to alleviate this heat by creating holes or air movement above the LEDs to allow the heat to escape and move away from the LED Driver.

      If I misunderstood your post about the LED lights being put on a breaker and not a dimmer switch, please let me know.

      However, the first thing to do in this case is to have the LEDs not flicker without any dimming installed at all.

      Thank you and have a wonderful day.

      Mark

  7. Hi Mark. Sorry if I mislead you in my post. All three sets of LED lights are on dimmer switches. When I say “sets” I’m referring to can lights in the kitchen ceiling, can lights above the fireplace, and LED ribbon lights under the kitchen cabinets. Each of the three sets are on their own dimmer, so I have three separate dimmer switches.

    When the dimmer is on full power, the flicker is gone (at least it is undetectable). I put the under-cabinet lights on their own breaker thinking that my issue was “noise” on the electric circuit but it obviously was not the solution.

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