Why Is My Leviton Dimmer Switch Making Lights Flicker?

Problem Description

Your Leviton dimmer switch causes lights to flicker, especially at low brightness levels. LED and CFL bulbs are more prone to flickering with dimmers than incandescent bulbs. Adjusting the low-end trim setting on the dimmer sets the minimum brightness level and prevents the flicker zone.

Why This Happens in Real Homes

Flicker on a Leviton dimmer, especially at low brightness, comes from the bulbs operating in a range the dimmer can't cleanly drive them through — LED and CFL bulbs are far more flicker-prone than the incandescents dimmers were originally designed for. There's a "flicker zone" near the bottom of the range where the current gets too low for the bulb's driver to hold a steady output.

The primary fix is the low-end trim: raise the dimmer's minimum-brightness setting until the lights stay solid at their lowest usable level, which lifts them out of the flicker zone. Pair that with dimmable, compatible bulbs (check Leviton's list) and keep one brand/type on the dimmer, since mixing widens the problem range. Make sure the load meets the dimmer's minimum, tighten the neutral, and update firmware. If flicker persists across good bulbs and a tuned trim, cheap LED drivers or circuit voltage fluctuation are the remaining suspects.

Symptoms

• Lights flicker on the dimmer
• Flicker at low brightness
• Flicker with LED/CFL bulbs
• Shimmer or strobe when dimmed
• Flicker in a certain range
• Occasional flashing
• Worse at the bottom of the range
• Flicker after a bulb change

Recognize these? Here's what usually causes it.

Common Causes

• Low-end trim set below the bulbs' minimum
• Non-dimmable or incompatible LED/CFL bulbs
• Mixed bulb brands/types on one dimmer
• Load below the dimmer's minimum
• Cheap LED drivers prone to flicker
• Loose neutral or wiring
• Voltage fluctuation on the circuit
• Firmware out of date

Tools & Requirements

Step-by-Step Solution

1

Check bulb compatibility first

LED flickering with a Leviton dimmer almost always comes down to bulb compatibility. Leviton publishes a compatibility list of tested LED bulbs on their website. Cheap or off-brand LEDs are the most common culprit — their drivers do not handle the dimming signal cleanly. Try a known-compatible bulb brand (Philips, Cree, or GE) and see if the flickering stops before testing anything else.

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2

Adjust the low-end trim

Flickering most commonly occurs at low brightness levels. The Leviton dimmer lets you set a minimum brightness floor. Hold the bottom of the rocker for 7 seconds to enter trim mode. Tap up to raise the minimum brightness until the flickering stops. This prevents the dimmer from operating in the range where your specific LED bulbs become unstable.

3

Check total wattage and minimum load

Leviton dimmers need a minimum load to operate the dimming circuit. A single 5W LED may be below the minimum, causing flickering. Add another bulb to the circuit to increase the load. Conversely, exceeding the maximum rated wattage (typically 300W for LED) also causes problems. Check both ends of the range.

4

Replace the dimmer if flickering persists with compatible bulbs

If you have confirmed compatible bulbs, correct wattage range, and adjusted the trim, and the dimmer still flickers, the dimmer triac (the component that controls dimming) may be failing. This is more common in dimmers that have been in service for several years. Leviton offers warranty replacements — contact their support with the model and serial number.

5

Rule out loose wiring

A loose wire connection inside the switch box can cause intermittent flickering that seems random. Turn off the breaker, pull the switch out, and check every wire connection. Tug each wire gently to confirm it is secure. Loose wire nuts or a wire that partially slipped out of a stab-in connector are common causes, especially in older installations where vibration has loosened connections over time.

Quick Solutions

Still having issues? This is usually the deeper cause below.

Need More Help? Leviton Support

Note: The contact information below connects you directly to Leviton's official customer support team, not Trunetto. They can help with warranty claims, device replacements, and advanced technical issues.