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LIGHTING INSIGHTS BLOG

Practical advice on commercial lighting from LED retrofts to lighting design

Here's an overview of common LED dimming issues and how to fix them

Posted by Brandon Melton on

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It wasn't that long ago we were answering the question: can LED lights be dimmed? The answer is yes, but years later problems can still surface when you try to run LED lamps or fixtures on dimmer controls.

Why are there still issues, even when lamps and fixtures are more reliable and dimmers more tolerant?

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Unfortunately, there's no easy answer. Diagnosing LED dimming issues is somewhat similar to diagnosing a sickness.

You start by checking vitals before looking at the symptoms of the issue.

In a dimming scenario, start with this checklist:

  1. Are these lamps in fact dimmable?
  2. Are the drivers in my fixtures dimmable?
  3. Are they compatible with the controls they're being paired with?
  4. And are those controls still in working condition, or have they surpassed their life rating?

In medicine, the symptom of coughing does not always indicate that a patient has a common cold. Dimming issues are similar. Different problems share similar symptoms, making it awfully difficult to diagnose the cause. (The good news is, we know a handful of cure-alls when it comes to this stuff.)

We'll go over common LED dimming problem symptoms later. Skip there now.


If there's a test you can perform, you use that to determine potential causes of the problem. If you show up at your doctor's office with a sore throat and a cough, she may just order a strep test for you, to definitively determine if strep throat is the cause of your symptoms.

With dimming, there are advanced tests that can be done to test out the cause behind the symptoms you're experiencing, but they can be time-consuming and often require expensive equipment.

To simplify the process, start with field tests, compatibility charts for the lamps or fixtures you're considering, and try multiple lamps on multiple dimmer switches.

One interesting note is that dimming is always related to the driver, which is a separate component in most fixtures and retrofit kits. Similar to lamps, a compatibility check at the beginning is critical to ensure success.

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Maybe you encountered these symptoms during the testing process. Or maybe you were previously encountering symptoms, and that's what prompted the testing.

Either way, the symptoms were probably one of the following.

7 common LED dimming issues

Throughout the history of lighting, problems tend to emerge when new technology is introduced to the market. There were issues dimming fluorescent lamps in the early days of that technology, just like LED lamps.

What we've seen over the last few years with the challenges of properly dimming LEDs are simply growing pains and, fortunately, as an industry, we appear to be past a lot of the significant problems.

A common issue with LED dimmability is sudden turn on or turn off when you try to adjust light levels with your dimmer switch. Or you may have "dead areas" as you slide your dimmer switch. Or your LED lamps may simply flicker or flash when paired with certain dimmer switches.

Here's how we'd describe some of those symptoms:

1. Drop out

This symptom occurs when you are trying to dim the lighting down and the light suddenly cuts out before you slide to the bottom of the switch.

2. Pop on

This is the inverse of "drop out" and occurs when you're sliding the dimmer switch on, to increase light levels, but your LED lamps suddenly turn on at a brighter level than you would normally except.

3. Dead travel

This symptom is present when your lamps don't respond to the adjustments you're making on the dimmer switch for certain sections of the dimming scale.

4. Ghosting

This symptom occurs when you've dimmed your lamps all the way down, but they continue to glow or produce small amounts of light.

5. Flickering

This symptom is understood as rapid, sporadic pulsing of your lamps when paired with dimmer switches.

6. Strobing

Similar to flickering, strobing occurs when your lamps rhythmically flash at a less-frequent rate than a flicker.

7. Flashing

This is understood to be a more sporadic, infrequent symptom of bad LED dimming, occurring when the lights randomly turn on and off when paired with a dimmer control.

LED dimming and new technology

Another problem we've noticed with LED dimming includes new lighting technology. This might sound backwards but using the latest and brightest lighting lamps and fixtures may not work for every setting.

For example, restaurants and hotels may want to set a certain ambiance using LED lights on a dimmer. New LED fixtures can be so bright and efficient, you have to take the lights down very low on the dimmer in order to get them to the right level. That's often when we notice problems.

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It takes a very specific fixture to be able to dim to your desire.

Not sure which fixture or lamp is best for your setting? Ask a lighting expert.

LEDs won't dim? Here's how to fix the problem

Whether your LEDs are flickering or randomly dropping out, most LED dimming problems can be avoided. Remember these four things:

  1. Not all LED lamps are dimmable. Make sure yours are.
  2. Not all controls work with dimmable LED lamps. Read the manufacturer’s compatibility charts.
  3. Some LEDs are just cheap and unproven. Buy well-tested product.
  4. Always perform a mockup.

Wondering what manufacturers have proven product or where to start with your LED purchase? Download our LED Buying Guide for everything from brand recommendations to warranty advice.

LED dimming and Title 24

If you're in California, you have a different set of regulations to consider for LED dimming. We dove headfirst into Title 24 several years ago. You can look through our resources and let us know if you have any questions.

Click here to learn more about LED dimming.

This article has been updated with the latest LED dimming information and technology. It was originally published in 2017.

LED Buying Guide to find the best pricing and right specs for LED lighting products