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Joined: Apr 2001
Posts: 41
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went out on a service call today and swapped out a couple of bad breakers.in 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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Joined: May 2001
Posts: 717
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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 to........so I gotta be the first. 2) IT DON'T KNOW THE WORDS. ![[Linked Image]](https://www.electrical-contractor.net/ubb/biggrin.gif)
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Joined: Apr 2001
Posts: 41
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what do u mean it dont know the words
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Joined: Apr 2001
Posts: 507
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Smokey,
Think about it a few minutes....it'll come to 'ya.
GJ
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Joined: Oct 2000
Posts: 5,392
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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?
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Joined: Mar 2002
Posts: 360
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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]](https://www.electrical-contractor.net/ubb/eek.gif) 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. trainwire
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Joined: Nov 2001
Posts: 745
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Smokey: 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]](https://www.electrical-contractor.net/ubb/smile.gif) Mike (mamills)
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Joined: Oct 2001
Posts: 597
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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
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Joined: Aug 2002
Posts: 1,081
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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 http://www.fluke.com/ElectricalPower/elec.asp (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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Posts: 264
Joined: February 2013
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