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#12693 08/14/02 09:22 PM
Joined: Apr 2001
Posts: 41
S
smokey Offline OP
Member
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...

#12694 08/14/02 09:37 PM
Joined: May 2001
Posts: 717
G
Member
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]

#12695 08/14/02 09:44 PM
Joined: Apr 2001
Posts: 41
S
smokey Offline OP
Member
what do u mean it dont know the words

#12696 08/14/02 10:05 PM
Joined: Apr 2001
Posts: 507
G
Member
Smokey,
Think about it a few minutes....it'll come to 'ya.

GJ

#12697 08/15/02 04:18 AM
Joined: Oct 2000
Posts: 5,389
S
Member
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?

#12698 08/15/02 05:14 AM
Joined: Mar 2002
Posts: 360
T
Member
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.
trainwire

#12699 08/15/02 10:47 AM
Joined: Nov 2001
Posts: 745
M
Member
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]

Mike (mamills)

#12700 08/15/02 11:23 AM
Joined: Oct 2001
Posts: 597
E
Member
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
#12701 08/15/02 01:24 PM
Joined: Aug 2002
Posts: 1,081
T
Member
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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