A faint, steady hum from an electrical panel can be normal, especially when large appliances are running. Loud buzzing, crackling or sizzling sounds are not normal and may point to loose connections, arcing, an overloaded circuit or a failing breaker.
Because these sounds can come with heat, they should be checked promptly.
Normal Sounds vs. Warning Sounds
Electrical equipment can make a low hum as current flows through it. Some breakers and panels hum slightly under heavy load, such as when an air conditioner or electric dryer is running.
Warning sounds are louder or more irregular. Buzzing that gets louder over time, crackling, popping or sizzling noises are signs that something may be wrong.
Sounds that come with a burning smell, heat, flickering lights or breakers tripping are more concerning than a quiet hum on its own.
Possible Causes of a Buzzing Panel
Loose connections are a common cause. When a wire is not tight at a breaker or terminal, electricity can arc across the small gap. Arcing can make a buzzing or crackling sound and produce heat.
A failing breaker can also buzz. If a breaker is not tripping as it should during an overload, it may hum or buzz as it strains.
Poor contact between a breaker and the bus bar can create noise and heat. Damage or corrosion inside the panel can contribute too.
Overloaded circuits can make a breaker work harder. In some cases, the sound may come from equipment near the panel rather than the panel itself, so a professional check helps confirm the source.
Why Buzzing Should Not Be Ignored
Arcing and loose connections create heat. Over time, that heat can damage breakers, wires and the panel. In serious cases, it can lead to a fire.
A breaker that is buzzing because it is not working properly may also fail to protect the circuit. That can leave the wiring at risk during an overload.
What to Do If Your Panel Is Buzzing
If you see smoke, sparks or flames, or smell burning, leave the home and call 911. Do not touch the panel.
If the buzzing is loud but there is no smoke or burning smell, avoid touching the panel and reduce the load by turning off large appliances if you can do so safely. Then contact an electrician.
Do not remove the panel cover or tighten anything yourself. Parts inside can remain energized even when breakers are off.
When you call, describe the sound, when it started and whether it changes when certain appliances run. That information can help narrow down the cause.
If your panel is making unusual sounds, our Denver electrical panel repair page explains how panel problems are found and fixed. Contact us to describe what you are hearing, and we can help you decide how quickly it should be checked.