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Intermittant brief buzz in service panel

Posted by pamela1963 (My Page) on
Sat, May 23, 09 at 2:17

I have an intermittant buzz coming from my service panel. The buzz lasts less than 1 second, and occurs as often as every 5 minutes or as seldom as once an hour.

I have removed and inspected all breakers, the bus bar and all wire connections with nothing unusual noted, so I figure it must be inside a breaker, but I don't know which one. I haven't had any breakers trip or fail, though this has been going on at least a year.

Any ideas?


Follow-Up Postings:

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RE: Intermittant brief buzz in service panel

It is caused by something intermitently (sp?) pulling a heavy load ie, appliance, heater, sump pump, well pump, etc...


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RE: Intermittant brief buzz in service panel

I thought the same thing, but am now convinced that loads are not a factor. As a matter of fact the only time I can hear it is when I am home alone, the house is silent and nothing is running (no loads other than clocks, lights, etc)


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RE: Intermittant brief buzz in service panel

I don't get it. Is lee1108 answering on pamela1963's behalf or are they the same person with two userids?


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RE: Intermittant brief buzz in service panel

Sorry tom, lee is my husband and I didn't realize he was logged in when I posted....can you help me?


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RE: Intermittant brief buzz in service panel

Have you narrowed it down to one breaker in particular? That in itself can be useful. Replacing that breaker may just resolve the issue if it is a simple vibration you are hearing. It is not necessarily anything to be concerned about, unless it is arcing you are hearing. This may be caused by a breaker not clamping tightly to the buss and exessive heat can result. This can be checked by someone who is comfortable and competent to turn off the main breaker, remove and inspect each breaker, the connecting clip on the back and the buss bar surface where the breaker attaches. They should all be clean, not black pitted or otherwise burned or showing any signs of heat.


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RE: Intermittant brief buzz in service panel

Some circuit breakers will make a buzzing sound when approaching their trip point. Often, intermitent buzzing is caused by the inrush of a motor. Refrigerators draw about 4 times running current at start-up, and NEMA motors may draw anywhere from 4 to 6 times running current. High effeciency motors have greater inrush than conventional motors. The noise is caused by the magnet armature of the "magnetic trip" part of the mechanism. For 60 cycle power, the magnetic buzz would have a 120 hz frequency.

This has been a design problem ever since manufacturers have been making circuit breakers for residential circuits.


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RE: Intermittant brief buzz in service panel

I have tried to isolate the breaker to no avail. I have sat out there (in the garage) for hours switching off breakers or groups of breakers and listening and waiting. Just when I think I have it figured out it buzzes again, no no matter what is switched on or off. It is difficult because it is so intermittant.

I have removed and inspected all the breakers, bus bars and wire clamps, no pitting or blackness.

The motor inrush theory makes sense, but it still happens when the breakers for all significant loads are off (fridge, freezer, ac, pumps, fish tank, tv, computer, etc) and nothing ia in use, nobody else home. The only loads would be clocks, a forgotten light or two and little transformers that stay plugged in like cell phone chargers.

I'm not too worried about it, but I will be having other work inspected soon and I fear it will concern the inspector. Do you think he/she will be concerned?


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RE: Intermittant brief buzz in service panel

It depends on what the actual noise is.

If it is an arc, the inspector should take notice.
Arcs cause long term damage, if only a little at a time by pitting and damaging the metal objects the arc is between.

If it is the vibration that occurs with a loaded breaker, it does not mean anything.


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RE: Intermittant brief buzz in service panel

Thats exactly what I am trying to find out, what the actual noise is.....

Can a trained ear (the inspector) tell just from the noise whether it is an arc or a loaded breaker vibration?

Can anyone describe to me the difference in the sound? It sounds like "Bwwwazzzzzzzzt" and lasts less then a second


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RE: Intermittant brief buzz in service panel

The inspector or an electrician should be able to tell the difference instantly.

One is a 60 Hz or 120 Hz vibration.
The arc is a sharper noise with a very crackling sound.


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RE: Intermittant brief buzz in service panel

Turn off _all_ of the breakers, see if there's still a buzz.

In addition, I've known a talented housefly or two to make a very accuate imitation of an electrical arc. Have you explored possible non-electrical causes?


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RE: Intermittant brief buzz in service panel

Thanks everyone for your helpful suggestions and advice. I just pulled ALL the breakers again, inspected everything with a flashlight and magnifying glass and reinstalled. No pitting, no blackening, etc. I am satisfied that nothing is arcing.

I also experimented again turning on and off breakers and testing loads. There is no buzz when ALL the breakers are off, but I still can't isolate it to one breaker or combination therof. There is also no correlation with deliberately created loads (fridge, pump, AC, etc)

I give up, and I will wait for the inspector.


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RE: Intermittant brief buzz in service panel

Is the meter box on the garage wall, directly
behind the panel box? If so, you might want
to look in there. But let the POCO know you
are cutting the seal, (or let them have a look).


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RE: Intermittant brief buzz in service panel

No, the meter box and main breaker are on the north end of the house. The load panel is in the garage on the south end of the house, quite far away.


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RE: Intermittant brief buzz in service panel

It will be followed by louder buzzes and less intermittency. When the buzzing gets so close it is almost constant then everyone gather around and watch.... KABOOM!!! Large mushroom cloud, electricity arcs and bellowing smoke. When it clears no more buzz. Have a hose handy just in case the house catches fire, but be careful not to hose the electrical panel.
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. Just joking.


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RE: Intermittant brief buzz in service panel

You mentioned cell phone charger, my battery charger for my cordless makes that kind of buzzing sound. If it is one of these new smart chargers it will randomly charge the cell phone, hence the random buzz.


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RE: Intermittant brief buzz in service panel

Dear Pamela: I am experiencing the same buzz however I am hearing it for the firt time 3/18/2011. How and what did your inspector find? How did you repair or elimnate?


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RE: Intermittant brief buzz in service panel

"I just pulled ALL the breakers again, inspected everything with a flashlight and magnifying glass and reinstalled. No pitting, no blackening, etc. I am satisfied that nothing is arcing."

You cannot see the internal contacts of a breaker to check for arcing damage, just the bus bar (input) and load screw (output).
A quick pass down all the breaker terminal with a torque screwdriver (or wrench with adapters) to check for tightness still might be worthwhile.
The screws need to be surprising tight for long term reliability.


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RE: Intermittant brief buzz in service panel

It is a bad grounding system from your breaker panel. Call an electrician to install the 2 ground rods, Copper, at 5/8" thick. Use 6 gauge solid wire with no splits to the breaker panel on the bus bar on primary ground. FIXED. Check all water and gas pipe for leaks, fix if any. Call your license professional to do the work. Good Luck. This help anyone?


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