Buzzing breaker panel

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Buzzing breaker panel

Postposted on Sat Feb 25, 2012 7:02 am

So what does it mean when a breaker panel makes a buzzing noise? I got it to stop by using some "percussive maintenance" (gave it a couple of good hard whacks with the palm of my hand), but should I be concerned?
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Re: Buzzing breaker panel

Postposted on Sat Feb 25, 2012 1:48 pm

just brew it! wrote:So what does it mean when a breaker panel makes a buzzing noise? I got it to stop by using some "percussive maintenance" (gave it a couple of good hard whacks with the palm of my hand), but should I be concerned?


50/60Hz hum? Few possibilities. One is that you have a loose connection that is arcing just slightly. Another is that the mechanics are just right so that the slight magnetostriction in the wire and/or breakers is at or very near the mechanical resonance of the box and so you here a nice "loud" hum. Could be a breaker signaling that it is reaching the end of its functional life through either of the above.

If it is the low smooth hum like you would hear from a large power transformer, I probably wouldn't worry too much. If it is the sharp sound of arcing, that is a different story.

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Re: Buzzing breaker panel

Postposted on Sat Feb 25, 2012 1:55 pm

I've never encountered it myself but I've been told the breakers don't last forever and that is one of they ways you can tell. I do know I had a few of those in-ceiling "can" lights that did this, and replacing them was the only way to fix it.
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Re: Buzzing breaker panel

Postposted on Sat Feb 25, 2012 2:08 pm

Open the panel door (i.e. don't take the cover off) and touch each breaker to see if one is getting hot. The hot one is likely the buzzing one.
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Re: Buzzing breaker panel

Postposted on Sat Feb 25, 2012 2:22 pm

Loose connection or failing breaker are two possible causes. Some new arc fault detectors have small transformers in them, which could theoretically hum. Percussive maintenance doesn't help that though.

Is it an old Federal Pacific panel? They're notorious for having connection problems in the bus bars and having breakers that fail. They went out of business in the US because of numerous law suits over safety failures and eventually had their certification pulled by Underwriters Laboratory.

Were any of the breakers abnormally warm? If answer is yes, turn it off and leave it off.

If you suspect there's a problem with your breaker panel get someone qualified to check it.

Edit to fix typo... Bit by Swype.
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Re: Buzzing breaker panel

Postposted on Sat Feb 25, 2012 2:32 pm

mnecaise wrote:Some new arc fault detectors have small transformers in them, which could theoretically hum.

I despise those arc-fault breakers. Damn things shut down at 5 amps on a 20 amp circuit for no good reason (fresh 12/2 Romex pulled last year and is still in perfect condition). That circuit needs to go back to a simple ground-fault breaker assuming I can find one.
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Re: Buzzing breaker panel

Postposted on Sat Feb 25, 2012 5:28 pm

None of them were warm, but the tone of the hum did change slightly when I touched one of them (before I whacked the panel). The hum has not come back.
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Re: Buzzing breaker panel

Postposted on Sat Feb 25, 2012 7:34 pm

just brew it! wrote:None of them were warm, but the tone of the hum did change slightly when I touched one of them (before I whacked the panel). The hum has not come back.


Well, it doesn't have to be that particular breaker, could be an adjacent one. Could be you reseated the breaker(s) in the bus bar when you whacked the panel. Personally, I don't like it when a panel makes noise. I'd keep an eye on it.
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Re: Buzzing breaker panel

Postposted on Sat Feb 25, 2012 8:06 pm

Please call an electrician. Won't take long for them to diagnose and I personally wouldn't find it worth the risk to let it go. I had a water-heater breaker go bad and damn near set fire to the wall. I just happened to wake up and smell the smoke in time.
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Re: Buzzing breaker panel

Postposted on Sat Feb 25, 2012 9:19 pm

Also could be the amount of power your using at the time on top of loose connections.

Stand inside an MCC room in a large industry and everything is torqued tight but the 60Hz humm is so loud you need earplugs (the wonderful sound of several megs of power moving along) although I doubt you would ever get that kind of noise at home.

Like another one said, check the brand of panel and breakers.

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Re: Buzzing breaker panel

Postposted on Sun Feb 26, 2012 12:15 am

You didn't mention if this was a residential panel or something else, but if the "something else" is a commercial or industrial application, high current flow is a possibility (as noted), and it's also possible there's a small step-down transformer mounted nearby to handle a low-voltage control circuit. Could have a mounting screw coming loose. Otherwise, it's definitely worth an electrician's time to tighten everything down. Snap-in breakers don't just come loose, if they are loosening up (or if the busbar is coming loose) there's a reason and it needs to be addressed.

Within the past couple years I've helped two different friends inspect and repair some electrical deficiencies in 70s-vintage homes and one of the first things that got done was to replace a number of breakers. Depending on exposure, exterior-mounted boxes can take a lot of thermal cycling and moisture ingress over the years and things corrode or get sticky. Any breaker that makes scraping noises, throws incorrectly, or doesn't 'catch' easily needs to be replaced. In one case, we even found a breaker that could not be tripped off -- the handle would catch about halfway without breaking the circuit, then spring back to the 'on' position. Eek :o
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Re: Buzzing breaker panel

Postposted on Sun Feb 26, 2012 12:17 pm

It's a residential panel. The panel is General Electric, but the breakers themselves do not have any visible brand markings on them; I assume that means the breakers are General Electric as well? There's also a sub-panel with Square D breakers in it, but the buzzing was not coming from the sub-panel.

Will definitely keep an eye (well, ear...) out for any further noises. It is right outside the door of my home office, so I will know if it comes back.
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Re: Buzzing breaker panel

Postposted on Sun Feb 26, 2012 12:24 pm

This happened about a year ago to me, the buzzing was very loud. It turned out to be a short , had an electrician disconnect said wire and viola no more buzzing and no more tripping breakers. Is there a switch or plug that once had power and now doesnt?
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Re: Buzzing breaker panel

Postposted on Sun Feb 26, 2012 12:26 pm

rogue426 wrote:This happened about a year ago to me, the buzzing was very loud. It turned out to be a short , had an electrician disconnect said wire and viola no more buzzing and no more tripping breakers. Is there a switch or plug that once had power and now doesnt?

Haven't noticed any outlets dying, and the breakers aren't tripping.
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Re: Buzzing breaker panel

Postposted on Sun Feb 26, 2012 1:32 pm

ludi wrote:it's also possible there's a small step-down transformer mounted nearby to handle a low-voltage control circuit. Could have a mounting screw coming loose.
Most household main panels have a small transformer strapped to the side for the doorbell circuit. Try poking that and see if it is loose.
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Re: Buzzing breaker panel

Postposted on Mon Feb 27, 2012 12:30 pm

just brew it! wrote:It's a residential panel. The panel is General Electric, but the breakers themselves do not have any visible brand markings on them; I assume that means the breakers are General Electric as well?

Should be. If you end up needing replacements, the off-the-shelf GE breakers at Home Depot or Lowes should swap directly.
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Re: Buzzing breaker panel

Postposted on Mon Feb 27, 2012 1:26 pm

A loose or dying circuit (worn out)breaker will cause a buzz, generally they buzz when under a heavy load and go silent under normal loads. It is not arcing, by the time you have arcing you would have a melted breaker. Normally the buzzing breaker would be hotter than those around it because of the heavier load (and possibly because a loose connectors generates heat) , using a laser thermometer will confirm it. Either way just replace it, before it trips and won't reset.
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