Hello there,

I've recently observed a transient humming/buzzing sound coming from my breaker panel. I have observed this twice in the last three days. I don't know how long it's been going on because the panel is located in the garage where I have rarely spent time prior to the last few weeks since I've been cleaning it out. Here's a short video of the sound: https://1drv.ms/v/s!AnfoU6HHFAzZiN0T0tQTehjCrE8Sug?e=ne4vd1. Note that you may also hear some background noise from the wind outside and the nearby water heater running.

In both cases that I've heard it, it lasts maybe 30s and then gradually dissipates.

Here's what I've done so far to try to isolate the source:

• Turned off each breaker one-by-one and turned them back on.
• Had someone turn on each major appliance and space heater in the house while I'm standing in front of the breaker.

Neither of these reproduced the sound. From what I've read online, a low-frequency humming sound coming from the panel can be normal--particularly when a load is initially applied to the circuit. However, I'm not sure if this qualifies as normal. Additionally, the breakers are all 44 years old. They have not been replaced since the house was built. From what I've read online, "modern breakers" are generally rated to last 15-20 years. However, it appears that some electricians do not see a reason to replace breakers based on age alone.

I am certainly willing to call an electrician to examine the issue to determine if there's a problem. But I was hoping to have more data beyond "I have this transient humming/buzzing sound that I can't reproduce". Any ideas on what else I could test?