# A faint hum



## chris856 (Jun 12, 2009)

Today I was changing a bad breaker in a twenty year old GE panel for a friend of a friend when I could hear a very quiet hum coming from it. I looked at the bussing and didn't see any signs of damage and I am pretty sure that the breaker wore out from tripping too much from being overloaded, not from any bad connection. My gut feeling is that something is wrong but I didn't say anything yet because I didn't want to freak out the homeowner for no reason. I think they would replace it if they thought something was wrong though.
What do you think?


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## user438 (Jun 6, 2007)

chris856 said:


> Today I was changing a bad breaker in a twenty year old GE panel for a friend of a friend when I could hear a very quiet hum coming from it. I looked at the bussing and didn't see any signs of damage and I am pretty sure that the breaker wore out from tripping too much from being overloaded, not from any bad connection. My gut feeling is that something is wrong but I didn't say anything yet because I didn't want to freak out the homeowner for no reason. I think they would replace it if they thought something was wrong though.
> What do you think?


Troubleshooting is not easy, most likely it sounds like the internal of breaker is bad. Only way to know for sure is to change it out. Was it still buzzing when you replaced it ? If it was then you need to tell them something is wrong.....and find it. If it stopped buzzing once you replaced it I would load that circuit up with as much as I could to verify.

A buzzing noise from a breaker panel is not normal and is very important that you find out where it is coming from


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## MDShunk (Jan 7, 2007)

For a measly 5-dollar breaker, and the person being your friend, just replace it. No reason to stress about it. Just slap a new one in there right quick. 

Old joke... why was the breaker humming? Because it doesn't know the words.


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## chris856 (Jun 12, 2009)

I'm sorry I worded that wrong, I did replace the breaker, it's the panel itself that makes the noise, I do plan on going over the whole thing and making sure everything is tight at least.


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## MDShunk (Jan 7, 2007)

chris856 said:


> I'm sorry I worded that wrong, I did replace the breaker, it's the panel itself that makes the noise, I do plan on going over the whole thing and making sure everything is tight at least.


Ah, gotcha. Yeah, something's likely loose, or another breaker is humming. Could even be the main. If the customer will tolerate it, unclip all the branch breakers and put them back in, one by one. If this is a dwelling, I doubt that it's the profile of a particular load causing the hum. In commercial, I'd start to think stuff like that.


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## RIVETER (Sep 26, 2009)

Is the service in conduit and possibly near the AC unit. Are there any other conduit enclosed circuits that may be near a source of vibration? Check for pipes going near or touching the ductwork. If not, I would stethoscope each breaker.


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## oldtimer (Jun 10, 2010)

RIVETER said:


> Is the service in conduit and possibly near the AC unit. Are there any other conduit enclosed circuits that may be near a source of vibration? Check for pipes going near or touching the ductwork. If not, I would stethoscope each breaker.


 Bulldog Pushmatic breakers used to hum a lot. Sometimes just resetting them would stop the hum.


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## Shockdoc (Mar 4, 2010)

main breaker hum under load , GE had a plug in main back in that day.It's likely that your main is either loose internally or at the plug connection. I would attempt to replace main breaker and if pitted at bus bar, emory clothe clean and noalox.


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## MF Dagger (Dec 24, 2007)

I had the same thing about a month ago, the culprit ended up being one of the nuts that held the one buss down to the breaker.


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## e57 (Jun 5, 2009)

Are there AFCI's or GFCI's in this panel? Hmmmmm.....

Is there a door bell transformer say mounted below it? Hmmmmmm....

Those are "hums" - arcing buss-work, loose connections or internal contacts of a CB is more of a "sizzle"..... :thumbsup: (Troubleshoot with an IR thermometer)

Now that said - ALL conductors vibrate to a degree under load - and will vibrate more depending on both the load, and the size of the conductor. And it will become audible if it has something to resonate against. I'm sure most of us can here a short or overload anywhere along the path of the conductor and recongize the sound - even be able to tell the differance between a short or an overload.... (Troubleshoot with an Ammeter - amp-clamp)



> I am pretty sure that the breaker wore out from tripping too much from being overloaded


Did you reduce the load on the circuit, or did you just replace the breaker?  Fix the cause or the effect?


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## 76nemo (Aug 13, 2008)

e57 said:


> Are there AFCI's or GFCI's in this panel? Hmmmmm.....
> 
> Is there a door bell transformer say mounted below it? Hmmmmmm....
> 
> ...


 
Troubleshoot with an IR thermometer?????:blink:

Troubleshoot a "panel" with an IR thermometer?????? Most don't even know how to use them correctly and don't have a clue on spot ratio. So again,..........


..........troubleshoot a panel with an IR gun:whistling2: Let me know how that works out for ya' ?????????


Not picking on ya' 57, just going forward. Good to see you over here as well:thumbsup:


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## e57 (Jun 5, 2009)

76nemo said:


> Troubleshoot with an IR thermometer?????:blink:
> 
> Troubleshoot a "panel" with an IR thermometer?????? Most don't even know how to use them correctly and don't have a clue on spot ratio. So again,..........
> 
> ...


YEP - damned straight.... Arcing creates heat and yes, and IR thermometer will help find it a lot better than what was suggested - a stethoscope.... :blink: Loose connections also produce heat.... (Like say poorly crimped weather head splices...) The breakers and terminals should not be too much higher than ambient - you spot a lot of heat - you can investigate further.

And yeah - just because I feel the need to keep some of you jokers in line in the 'off topic' area - I am an electrician as well.... Believe it or not...


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## 76nemo (Aug 13, 2008)

e57 said:


> YEP - damned straight.... Arcing creates heat and yes, and IR thermometer will help find it a lot better than what was suggested - a stethoscope.... :blink: Loose connections also produce heat.... (Like say poorly crimped weather head splices...) The breakers and terminals should not be too much higher than ambient - you spot a lot of heat - you can investigate further.
> 
> And yeah - just because I feel the need to keep some of you jokers in line in the 'off topic' area - I am an electrician as well.... Believe it or not...


 

So I shall ask you this. What gun are you using and what is the spot ratio???? If you're talking a camera, the conversation is over, but an IR gun pinpointing true specifics? Sorry, e57, just don't see it. You would be 250 X's better off to use a contact surface measurement device. I would go as far to say any IR gun in the lower to middle range would be quite useless in a panel. You'll need a gun capable of spotting/centering on tandem breakers to pinpoint smaller spot-ons such a bussing, bolting and stabs. Their $250 IR gun isn't going to cut it, not even close:no:

What if they own a device capable of doing those specifics accordingly, do they know in the least on how to properly use it, and determine solid conclusion????


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## e57 (Jun 5, 2009)

76nemo said:


> So I shall ask you this. What gun are you using and what is the spot ratio???? If you're talking a camera, the conversation is over, but an IR gun pinpointing true specifics? Sorry, e57, just don't see it. You would be 250 X's better off to use a contact surface measurement device. I would go as far to say any IR gun in the lower to middle range would be quite useless in a panel. You'll need a gun capable of spotting/centering on tandem breakers to pinpoint smaller spot-ons such a bussing, bolting and stabs. Their $250 IR gun isn't going to cut it, not even close:no:
> 
> What if they own a device capable of doing those specifics accordingly, do they know in the least on how to properly use it, and determine solid conclusion????


I Have a fluke 63 - spot ratio is merely 12:1 - but it DOES NOT TAKE MUCH.... The spot is like an inch or so at a foot - and that is all it takes. 


'Hot breaker - but moderate load - maybe I'll look into that.....'
'Gee that neutral is ~100F above all the other terminations - maybe I look into that....'
'For some reason those 3 breakers are hotter than all the rest - hey and low and behold - the buss is all black and charred under there...'
'Hey that track fitting is 200F - and there is no light near it - maybe that's why this track section keeps going out?'
This is not rocket science.... (Not gonna suggest you use your tongue... :whistling2 

Heat for the most part in the above situations is radiating out on other parts - Breakers far hotter than others in a panel with a low moderate load can point to an issue with the breaker, bad crimps at say a weather head will be far in excess tempature than the conductors, buss stabs will heat up several breakers, and no track fitting should approch a temp that would melt it....

Sure you could grab a contact thermometer - but that is contact often with possibly energized conductors under load, and just plain time consuming.... You could also hire out someone or rent a flir camera if you want "True specifics". But why? It does not need to be "99.999% ACCURATE" - it just needs to lead you in the direction to investigate....  Once you localized a possible issue - you 'could' grab a contact thermometer - or you could have found a symptom that fits the effect and make a reasonable - often common sense conclusion...

OBTW who is "THEY"? Who is this "They" you speak of? If they own one - it most likely came with instructions...


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## 76nemo (Aug 13, 2008)

The instructions that come with those guns are like directions for car soap. Mix with water, scrub, maybe repeat.

I'd go as far to say 75% of people walking around toting a nice new IR gun don't know squat on how they're properly used:no:

63, nice gun. Motors, starters, large fuses, gen heads, whatever, grrreat


A 60 series type IR gun is great for preventive maintenance, and to always carry on you like a T5, but I am not talking more of the maintenance side of things E. What I meant as "far" as troubleshooting possible breaker/termination problems with an IR gun, you'd really need to look into something like the 570 CF series. We're talking .24" min. spot diameter and 50:1 ratio.

That compared to the 60 series is like comparing their 114DMM against their 87V,............big difference:001_huh:


See more details???.......................................


http://www.tequipment.net/Fluke572CF.html


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## e57 (Jun 5, 2009)

Sure its fancy - it's pricey too. Yep probably a lot more accurate than mine - but not completely necessary IMO.


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## RIVETER (Sep 26, 2009)

e57 said:


> YEP - damned straight.... Arcing creates heat and yes, and IR thermometer will help find it a lot better than what was suggested - a stethoscope.... :blink: Loose connections also produce heat.... (Like say poorly crimped weather head splices...) The breakers and terminals should not be too much higher than ambient - you spot a lot of heat - you can investigate further.
> 
> And yeah - just because I feel the need to keep some of you jokers in line in the 'off topic' area - I am an electrician as well.... Believe it or not...


I know the value of the IR. I use and am certified. The stethoscope was to listen for the vibration and possibly find the source. Plus they are fun to use, but I am not a doctor. Mine is the enlongated needle type...and I am talking about my stethoscope.


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## 76nemo (Aug 13, 2008)

e57 said:


> Sure its fancy - it's pricey too. Yep probably a lot more accurate than mine - but not completely necessary IMO.


 
I'm not trying to sell you one, I was trying to make a point of the differences in these devices considering many different applications, and scenarios.

Alot of sensible people think,..."Just point, and shoot".:001_huh: You know that is not the case at all. These things are not magical, all they are is a "quote" measurement to most.


A min. 1" spot diameter is useless in MANY applications. 

I'll quit rambling E. Again, good to see you here as well


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## mattsilkwood (Sep 21, 2008)

e57 said:


> I Have a fluke 63 - spot ratio is merely 12:1 - but it DOES NOT TAKE MUCH.... The spot is like an inch or so at a foot - and that is all it takes.
> 
> 
> 'Hot breaker - but moderate load - maybe I'll look into that.....'
> ...


 I have the same one and use it in much the same way. Nemo is right, it's not a precision instrument, but it will point you in the right direction.


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## brian john (Mar 11, 2007)

Shut off on CB at a time till the hum goes away.


I'd bet the hum is another CB.

Perform a FOP on the panel
Perform an FOP on each CB or the bad CB


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