Overview: Common LED dimming issues and how to fix them


It wasn’t that long ago that we were answering the question: can LED lights be dimmed? The answer is yes, but problems can still surface years later 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?

Unfortunately, there’s no easy answer. Diagnosing LED dimming issues is somewhat similar to analyzing 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.

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.

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 passed 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 expect.

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 the 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.

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 a well-tested product.
  4. Always perform a mockup.

Wondering what manufacturers have proven products or where to start with your LED purchase? Follow us @Zohnson LED Lighting for everything from brand recommendations to warranty advice.



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Hi, I’m Betty, from the Zohnson Sales Team, We have been running a factory in China that makes Led Lights for 10 years now, and the purpose of this article is to share with you the knowledge related to led lights from a Chinese supplier’s perspective.

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