Lights flicker when a specific appliance turns on

Symptoms

• Lights dim briefly when the AC, fridge, or a motor kicks on
• Flicker happens consistently with the same appliance
• Sometimes paired with a slight buzz from the panel

Likely causes

• CommonNormal inrush current from a large motor startingAC units, well pumps, and furnace blowers draw a brief surge of current at startup that can dim lights slightly.
• CommonThat appliance sharing a circuit with the lightsPutting a large appliance on the same circuit as lighting makes the dip more noticeable.
• PossibleA loose neutral connection at the panel or meterThis can cause more dramatic and inconsistent flickering, not just a brief dip.
• PossibleAn undersized wire or connection feeding that applianceA wire run that's too long or thin for the load can cause voltage drop when it starts.

What to do

1. Note whether the flicker is a brief, mild dip or a noticeable, longer flicker.
2. Check whether the appliance and the flickering lights are on the same circuit or breaker.
3. If they share a circuit, consider having the appliance moved to its own dedicated circuit.
4. If the flicker is severe, affects lights on other circuits too, or comes with buzzing, treat it as a possible loose connection.
5. Have an electrician check the wire size feeding large appliances like AC units or well pumps.
6. Ask about a dedicated circuit for major appliances if this hasn't been done already.
7. Have the panel and main neutral connections checked if flicker isn't limited to one shared circuit.

When to call a pro

Call an electrician if the flicker is more than a brief, mild dip, affects circuits beyond the one the appliance is on, or is getting worse over time.

Safety