Buzzing or humming from an outlet, switch or panel

A light that buzzes only when dimmed is usually a bulb and dimmer that do not match. A steady buzz from an outlet, switch or the panel often means a loose connection or arcing, which is an electrician's job. Find where the sound comes from first.

Also searched as: outlet buzzing, outlet buzzing nothing plugged in, light switch buzzing, light switch buzzing dimmer.

Before you start. If you see smoke or flames, get out and call 911. Do not open the panel or remove any cover to find a buzz.

A bright laundry room with a washer and dryer, shelving and a utility sink

Every question and answer on this page, in order

Question 1: Do you see smoke, or smell burning at the panel?

Check from a step back. Do not touch the panel to find out.

Question 2: Where is the sound coming from?

Turn off other noise and move your ear close, without touching anything.

The electrical panel or a breaker: Call an electrician: a buzzing panel or breaker
The electric meter outside: Call the utility: noise at the meter
A light fixture, a bulb or a dimmer: go to question 3
An outlet or a standard switch: go to question 4

Question 3: Does it buzz only when dimmed, or only with certain bulbs?

Turn the dimmer to full and listen, then dim it.

Yes, only when dimmed or with certain bulbs: Likely cause: a bulb or a bulb and dimmer mismatch
No, it buzzes at every setting with any bulb: Likely cause: a loose connection or arcing

Question 4: Is there any heat, a burning smell, sparks or crackling?

Touch the cover plate lightly with the back of your fingers, and sniff near it.

Yes: Stop: buzzing with heat, smell or sparks
No, just a steady buzz, even with nothing plugged in: Likely cause: a loose connection or arcing

Possible results

Need the words for the phone call? Build a what-to-tell-the-electrician checklist, or read when to call an electrician.