This is normal
Usually normal: a brief dip when a big appliance starts
A short dim when the AC, furnace fan or another large appliance starts is a momentary voltage drop. If it is frequent or severe, call an electrician.
Why this happens
Bob Vila explains that a brief dim when a large appliance starts is a voltage drop. A dip that lasts a moment and then settles fits that pattern. Bob Vila also says dimming that is frequent or severe should be checked by an electrician.
What to do
- Watch which appliance causes the dip, and how long it lasts.
- If it is brief and only happens at start-up, no action is needed.
- If lights dim often, dim deeply, or stay dim, call a licensed electrician.
When to stop. Flicker that happens on its own, gets worse, or comes with a burning smell is not normal.
If it still worries you, tell the licensed electrician
- Which appliance causes the dip and how long it lasts.
- Whether it happens in one room or the whole house.
- Whether it has gotten worse over time.
Build the full list: what to tell the licensed electrician.
Start this troubleshooter over
References (every fact above comes from one of these pages)
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