Is it normal for the main circuit board to hum?

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  #1  
Old 11-21-12, 03:24 PM
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Is it normal for the main circuit board to hum?

Spend some time at the main board looking for a specific breaker then I noticed that it was quietly humming. Is that normal?

Tia Steve
 
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Old 11-21-12, 04:42 PM
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No, that isn't normal - but it can happen. I would check for something not as tight as it should be. If you're comfortable working inside a live panel, you can turn the main breaker off, open the panel, and push on the inner edge of each breaker to make sure it's fully seated. Then read the torque values on the panel label and gently but firmly try tightening each of the screws holding the branch circuit hot wires in their breakers to the appropriate value.

You can also check the torque on the screws terminating the neutral and ground wires, and check to make sure that each neutral wire is under a screw by itself.

This is actually a maintenance procedure that is done once a year at many commercial properties. It should be done in every panel, but usually isn't done in residences.

Just as a note, you will need some good battery-powered light as you do this!
 
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Old 11-21-12, 05:14 PM
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But DO NOT try to tighten the main breaker screws. They are HOT even with the breaker off.
 
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Old 11-21-12, 05:59 PM
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Spend some time at the main board looking for a specific breaker then I noticed that it was quietly humming
You probably have a branch breaker humming. If you have access to ultrasonic testing equipment or a stethoscope, it shouldn't be hard to find. Once you find it, replace it.
 
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Old 11-21-12, 06:09 PM
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Some of the magnetic trip breakers hum when a load is drawn on them.
 
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Old 11-21-12, 06:52 PM
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If I was to trip each breaker one by one and listen and if it stopped would that be a way to find the problem? The main would still be on in this case. Would the humming be a sign of a bad breaker besides there being something loose ? I googled this and one guy said it was simply his meter outside that he heard but I think mine is too far,kinda around the corner. Is this a dangerous situation for my home?
Thx,
Steve
 
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Old 11-21-12, 07:04 PM
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If I was to trip each breaker one by one and listen and if it stopped would that be a way to find the problem?
Yes, that would be a good thing to try.
 
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Old 11-21-12, 07:30 PM
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No luck. I hit the main off and the humming ended. Prior to that I checked each breaker independently, the humming never stopped. It is very faint but its there and its an issue. I'll take the cabin off tomorrow, but there would have to be more than one loose spot.
thx,
Steve
 
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Old 11-21-12, 09:40 PM
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Or the main needs tightening - not a DIY job.

Yes, there may be more than one place that needs tightening. As I said, the routine is to go through each circuit - even if you stop the humming before you get to all of them.
 
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Old 11-22-12, 05:10 AM
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Electrical equipment can, and will hum. It is called 60 cycle hum. It could be a non-issue.
 
  #11  
Old 11-22-12, 05:50 AM
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I've heard this on almost every GE panel I've been near, as well as some AFCI and GFCI breakers.
 
  #12  
Old 11-22-12, 06:01 AM
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I hit the main off and the humming ended. Prior to that I checked each breaker independently, the humming never stopped
The severity of the humming is something only you can determine, we can't hear it. I once had a 2 pole breaker on an air conditioning circuit that would hum badly when the breaker was turned on under load. By turning the air conditioner off before energizing the breaker, the breaker no longer hummed when the air conditioner was turned on.
 
  #13  
Old 11-23-12, 09:48 AM
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I would get those main lugs checked by an electrician. Loose main lugs can be very dangerous. A restaurant I owned once had one of the main feeds loose. We figured this out when the main breaker tripped, I went to go flip it back on the the whole top half of the breaker box was glowing red hot. Ended up setting the wall cavity on fire. Even if that is not the issue, better to be safe than sorry.
 
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