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humming panel #12693 08/14/02 10:22 PM
Joined: Apr 2001
Posts: 41
smokey Offline OP
went out on a service call today and swapped out a couple of bad the process i heard a humming sound coming from inside the panel. any suggestions on what may be causing the humming sound...

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Re: humming panel #12694 08/14/02 10:37 PM
Joined: May 2001
Posts: 717
George Corron Offline
OK, I've had a REAL bad day.
1) Something is loose, usually a breaker, could even be inside a breaker. Take the insulated end of your screwdriver and GENTLY put pressure on each breaker, when the humming stops, you found it. Could also be the buss bar, however.

Like I said, I had a real bad day. Went to work at 5 am, it's about 10:40pm, and I just got home, and we did not accomplish what we wanted I gotta be the first.

2) IT DON'T KNOW THE WORDS. [Linked Image]

Re: humming panel #12695 08/14/02 10:44 PM
Joined: Apr 2001
Posts: 41
smokey Offline OP
what do u mean it dont know the words

Re: humming panel #12696 08/14/02 11:05 PM
Joined: Apr 2001
Posts: 507
golf junkie Offline
Think about it a few'll come to 'ya.


Re: humming panel #12697 08/15/02 05:18 AM
Joined: Oct 2000
Posts: 5,389
sparky Offline
Even brandy new installs seem to buzz with a motor load starting.
I imagine this is 60Hz vibrating the innards of breakers, as all else is new/tight?

Re: humming panel #12698 08/15/02 06:14 AM
Joined: Mar 2002
Posts: 360
Trainwire Offline
If nothin's hot, and it doesn't change by pressing on the breakers, I would say it's the nature of the panel, sometimes what it's mounted to makes it sound louder than it is, like the big board in the back of a piano. However if it's a buzz, or a fuzz sound rather than a hum [Linked Image]
The other thing is, what was on? The water heater, dryer, a/c, some other heavy load?
Things like this keep a person up at night.

Re: humming panel #12699 08/15/02 11:47 AM
Joined: Nov 2001
Posts: 745
mamills Offline
Just a random thought...could it possibly be a mechanical noise from another piece of equipment or machinery being coupled to the panel through a conduit? I have also seen (aka heard) circuit breakers buzz when loaded pretty close to their ampacity.

George; sometimes I don't know the words either...HMMM, HMMM, HMMM... [Linked Image]

Mike (mamills)

Re: humming panel #12700 08/15/02 12:23 PM
Joined: Oct 2001
Posts: 597
ElectricAL Offline
Is the doorbell transformer in one of the knockouts on the side of the panel? A really cheap one will have core laminations that flap in the wind.

Al Hildenbrand
Re: humming panel #12701 08/15/02 02:24 PM
Joined: Aug 2002
Posts: 1,081
ThinkGood Offline
This is a real shot in the dark...and hopefully is not going to cause you more work for naught.

Maybe the cause of the humming is power harmonics?

There's a PDF file at (go to Application Notes, which is on the left menu, third up from the bottom).

The PDF is entitled "In Tune With Power Harmonics" and on page 4 mentions humming panels.


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