Why Does My Leviton Decora Smart Dimmer Flicker Only After Sunset

Problem Description

Some Leviton Decora smart dimmer users report flicker only after sunset, with no issue during the day. This guide explains how grid load patterns, LED driver behavior, and scene triggers combine to create evening-only flicker.

Symptoms

• Flicker appears only after sunset
• No flicker during daytime use
• All bulbs in circuit flicker together
• Issue intensifies during peak evening hours
• Smart schedule runs near the same time
• Voltage elsewhere feels slightly lower

Recognize these? Here's what usually causes it.

Common Causes

• Evening grid voltage drops below threshold
• LED drivers marginal under lower voltage
• Schedule dim level too low for load
• Motion sensor retrigger adds ramp pulses
• Shared neutral issue in branch circuit
• Firmware handling of dim ramp changed

Tools & Requirements

Step-by-Step Solution

1

Measure Voltage Day vs Night

Use a multimeter at a nearby outlet on the same branch circuit. Measure voltage midday and again after sunset. If evening voltage drops 5V or more, grid-related sag is making the LED drivers marginal at lower dim levels. Document readings for later comparison.

Needed for this step

Klein Tools 80196 Digital Multimeter Kit with C...

$46.15

Get It on Amazon

2

Try Known-Good LED Bulbs

Replace the bulbs with premium LED lamps rated for dimming and listed on the Leviton compatibility sheet. Many evening-only flicker reports trace to cheap drivers that fail under both dim command and grid sag simultaneously. Premium drivers are far more tolerant.

3

Raise Evening Minimum Dim

In the Leviton app, raise the scheduled evening dim level to at least 30 to 40 percent. If scenes drop below the driver minimum during voltage sag, flicker is guaranteed. A small lift eliminates flicker without significantly changing the visual ambiance.

Needed for this step

NJTY Non-Contact Voltage Tester with Laser Guid...

$5.99

Get It on Amazon

4

Audit Triggers

Check for motion triggers, geofence events, or scene transitions that fire near sunset. Rapid ramp commands from overlapping automations can make flicker appear evening-specific. Consolidate automations so only one commands the dimmer during the evening window.

5

Inspect Neutral and Update

Verify neutral connections at the panel and in the switch box are tight and free of browning. A poor shared neutral in branch wiring can manifest evening-only when other loads increase. Finally, update Leviton app and dimmer firmware and retest two evenings.

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.