Symptoms
- Audible hum or buzz coming from the panel box
- Buzzing louder near one specific breaker
- Sometimes paired with warmth on the panel cover
Likely causes
- CommonA loose breaker or wire connectionLoose connections arc slightly, producing a buzzing sound and heat.
- CommonA failing breakerInternal breaker components can hum as they wear out.
- PossibleNormal transformer hum from certain breaker typesSome AFCI or GFCI breakers have a faint, constant, low-level hum that is normal.
- PossibleAn overloaded circuit at that breakerA breaker running near its rated capacity can hum under load.
What to do
- Note which breaker the sound seems to come from, and whether it's constant or load-dependent.
- Feel the panel cover for warmth near that breaker, but don't touch anything inside.
- Do not open the panel's dead front cover yourself; it stays energized even with breakers off.
- Reduce load on that circuit temporarily if you suspect overload.
- Note if the hum is faint and constant across the whole panel versus loud from one spot.
- Call a licensed electrician to open the panel safely and check for loose or failing connections.
- Treat any buzzing paired with a burning smell as urgent and shut off the main breaker.
When to call a pro
Call a licensed electrician to inspect any panel that hums loudly, feels warm, or has a hum that's gotten noticeably louder over time.
Safety
Use caution
Never open the panel's dead front cover yourself. If you smell burning along with the hum, shut off the main breaker if you can do so safely and call an electrician.