Buzzing breakers

[Sparkdizzle]

He said it was at a Starbucks, not really sure what is typical for them for equipment. VFD's (larger ones anyway) would most likely be on HVAC, but I could see cooking or other heating equipment possibly being solid state controlled and have some similar non linear characteristics and non linear lighting loads.

It’s exactly what you’d expect from a compact crowded little commercial kitchen. A lot of small appliances, food warmers, mini fridges, ice machine etc....No VFDs.
I’m thinking about going back there sometime during off-peak hours on my own time and investigate a little more.





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[Sparkdizzle]

toss in some Starbucks metal straws, see when the buzzing stops hmy:
maybe some gremlins have a nest behind the panel in the wall?
but, not sure what the point of post is if the OP is not engaged in the project. some buzzing OCPD's........................ and?

I suspect you’ve heard these kinds of noises before coming from a whole panel before. I have not. And I’ve been around a few. When I encounter strange things like this in our trade, I always come to the forum to find answers. I’ve learned a lot over the years by doing so. This was someone else’s warranty work, but I’m still curious about why/how.


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[sameguy]

To me and didn't run the video, you need to be there before opening to hear the panel as load is added.
Going in on your own, not a service call, puts you/company on the liability if you turn a breaker off.

 

[kwired]

He said it was at a Starbucks, not really sure what is typical for them for equipment. VFD's (larger ones anyway) would most likely be on HVAC, but I could see cooking or other heating equipment possibly being solid state controlled and have some similar non linear characteristics and non linear lighting loads.
It’s exactly what you’d expect from a compact crowded little commercial kitchen. A lot of small appliances, food warmers, mini fridges, ice machine etc....No VFDs.
I’m thinking about going back there sometime during off-peak hours on my own time and investigate a little more.





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But do any of those appliances incuding the HVAC have VFD's or other solid state controllers (talking solid state control of the main power circuit, not just the control circuit) within them? I'm guessing some do but if a majority of them do, I can see those effects being more noticeable than if you only had limited appliances like this.

 

[Sparkdizzle]

To me and didn't run the video, you need to be there before opening to hear the panel as load is added.
Going in on your own, not a service call, puts you/company on the liability if you turn a breaker off.

That’s a really good point.


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[Jamesco]

He said it was at a Starbucks, not really sure what is typical for them for equipment. VFD's (larger ones anyway) would most likely be on HVAC, but I could see cooking or other heating equipment possibly being solid state controlled and have some similar non linear characteristics and non linear lighting loads.

It’s exactly what you’d expect from a compact crowded little commercial kitchen. A lot of small appliances, food warmers, mini fridges, ice machine etc....No VFDs.
I’m thinking about going back there sometime during off-peak hours on my own time and investigate a little more.

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In what type of setting?
In a Mall?
In a Strip Mall?
In a Barnes and Noble Book Store?
In a ???

What is the world beyond the confines of the Starbucks?

Hello all!
Big fan of the forum, but first post.

I received a service call last week at a Starbucks from an HVAC tech concerning a breaker that was apparently “sparking really bad” when he was attempting to verify voltage in the panel for an Ice machine. I figured it was simply a loose connection. When I got there I found out the store is essentially BRAND NEW, having just been renovated and only re-opened for five days.

Now, I locate the panel of the breaker in question and hear a cacophony of erratic buzzing from this panel when I opened it. It sounded load based, coming and going quite randomly, but seemed to be coming mostly from the 2p breakers, but it was very hard to tell. I tried putting my(gloved)hand on whichever breakers I thought the buzzing was coming from, thinking maybe loose connection, but nothing. It was unnerving.

Brand new. Brand new electrical service? New electrical panel and breakers?
OR,
Existing electrical panel? Existing circuit breakers?
Aluminum bus?
My first thought when I started reading your posted message, the panel is existing, the bus is AL and a circuit breaker to AL bus connection is arcing under load due to a poor connection.

Then I listened to the sound on the video you provided in your next post. It kind of sounds like a digital repeating signal to me.

 

[FionaZuppa]

I suspect you’ve heard these kinds of noises before coming from a whole panel before. I have not. And I’ve been around a few. When I encounter strange things like this in our trade, I always come to the forum to find answers. I’ve learned a lot over the years by doing so. This was someone else’s warranty work, but I’m still curious about why/how.


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I play nice.

Too many variables to know why for sure. That's the answer.

Some panels hum. OCPD's are mostly magnetic devices operating in mag field that is created and destroyed by AC. They always vibrate, but most times you don't hear them. Wht does a xfrmer hum away when under heavy load? One OCPD amps can be magnetically coupling to an adjacent one where the stab/lock is not tight enough. There could also be resonance going on where a small db noise is amplified by the physical characteristics that surround it. Dunno exactly, too many things that can be possible suspects.

 

[readydave8]

I did not listen to video

but had a panel buzzing one time that turned out to be the bees in the wall behind it

 

[kwired]

It was definitely not a 60 cycle hum from what I was hearing.

Remember that equipment designed around operating at 60Hz. Supply volts is still 60 Hz, but if you get a bunch of solid state switching at high frequencies, the current and resulting magnetic fields associated with current and anything else impacted by those magnetic fields are all happening at those higher frequencies.

Current waveforms in those situations are not sinusoidal either which makes the sound different from the usual 60 cycle hum.

 

[ptonsparky]

FWIW:

 

[FionaZuppa]

1kHz is pretty high, 4.5kHz is way high, which is near the end of human ear as an elderly person.

The video was not carrying a 4.5kHz audio tone to the person watching the video, not even close.

That phone app may be picking up 4.5kHz but I dont think that was the humming.

 

[ptonsparky]

1kHz is pretty high, 4.5kHz is way high, which is near the end of human ear as an elderly person.

The video was not carrying a 4.5kHz audio tone to the person watching the video, not even close.

That phone app may be picking up 4.5kHz but I dont think that was the humming.

IDK, there is a whole range of frequencies in there to choose from.

 

[Cow]

I would isolate which breakers were making the noise.

Then I would proceed to rap a screwdriver handle against the face of the breaker to see if that changed the noise or hum at all, which would indicate to me that the internal breaker contacts may not be seating against each other properly.

If it was a poor breaker to bus connection, you would be seeing signs of heat and the breakers would most likely be warm/hot to the touch.

In any case, I wouldn't have touched anything either, and would have asked where the electrician was that they used for the renovation?

 

[iceworm]

I really tried - really

Mosquitos are at 17.4KHZ - so DEET won't help.

Gasp - Choke (picture Dr Strangelove choking himself with his artificial hand)

 

[ritelec]

My thought... the white dust on the breakers and the buss bars are white looks like it's corroding and the breakers are burning..

Was a couple months back and the buss bars in a residential panel looked like those busses, and several breakers burnt (melted down) and failed at the buss bar stab ( I think they were actually all pretty shot and failing ).. it was a basement with a sump pump next to the panel that would run alot...Listening again, it does sound like arcing...(to me)

 

[rt66electric]

I have heard a similar sound from a BR breaker

I have heard a similar sound from a BR breaker

I have heard a similar sound coming from a BR breaker when there was a direct short.

Flipped the breaker on and it made a horrid sound, I acted as if it wasn't going to trip before I shut it off manually.

 

[kwired]

My thought... the white dust on the breakers and the buss bars are white looks like it's corroding and the breakers are burning..

Was a couple months back and the buss bars in a residential panel looked like those busses, and several breakers burnt (melted down) and failed at the buss bar stab ( I think they were actually all pretty shot and failing ).. it was a basement with a sump pump next to the panel that would run alot...Listening again, it does sound like arcing...(to me)

OP's panel is presumably new enough there better not be that kind of corrosion on bus bars yet. Only white dust I saw looked like it could easily be drywall dust.

 

[Sparkdizzle]

Thank you all for the ideas and insight on this!!

 

[ritelec]

OP's panel is presumably new enough there better not be that kind of corrosion on bus bars yet. Only white dust I saw looked like it could easily be drywall dust.

??? Having just been renovated ??? But maybe you're right ?

 

[D Hollenbeck]

Buzzing breaker...

Buzzing breaker...

Just 2 cents worth; Had an installer in for new counter tops. They did alot of trimming of the Corian outside; noticed a buzzing from the breaker panel. Looked at his setup; motor connected with a 5-15 plug; however the motor load was 2000 watts on it's placard. Really buzzed under cutting load, so i guess I was lucky my 15a breaker didn't flip. When he paused i cycled the breaker but buzzing started again when cutting. Cuts were short in duration so that may have helped, but bet I was at the breaker tolerance level (20%?) (CH panel)