Strange Humming in Panel

Little Bill

Little Bill

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Location
Tennessee NEC:2017
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Semi-Retired Electrician
Had a guy call me to check out a hum and buzzing noise in the panel. The hum seemed to not be anything I would worry about as I've heard that before. However, when breaker for the air handler for the AC unit was turned off and back on, you could hear the buzzing/arcing sound.
I checked all the lugs and terminals for breakers and all were tight. There is an outside disconnect so I checked the lugs there and all was good.
Also had the POCO come and check their connections and all was good there.

The noise seemed to be coming from the main breaker. The panel is a SqD Homeline 200A main breaker. So I was going to contact them.

They also wanted me to change out some dimmers for regular switches as their LED lights would sometimes flicker badly when on the dimmer. The dimmers had been changed by me just a few weeks ago. But the guy said the lights started to flicker again. I told him the LED lights, which are the wafer recessed type lights, were probably not working right with the dimmers. The dimmers were 3-way and I didn't have any 3-way regular switches with me.
The guy said he would pick some up and change them out.

Here's the odd part.
He called me a while ago and said he got them changed. He says all the flickering, humming and buzzing have stopped. I knew the flickering would stop, but what would changing dimmers out for regular switches have to do with the arcing/buzzing sound coming from the panel?
I told him to keep an eye on it and listen for the arcing sound. I am not convinced that it has stopped!
 
Does the power company use "TWACS" for reading their meters? See the older thread below:

TWACS flickering?

How many have ever heard of TWACS causing flickering lights? Anyone ever ran into a flickering lights problem that can’t be explained any other way other than signal modulation due to the POCO communication system?
forums.mikeholt.com
 
synchro said:
Does the power company use "TWACS" for reading their meters? See the older thread below:

TWACS flickering?

How many have ever heard of TWACS causing flickering lights? Anyone ever ran into a flickering lights problem that can’t be explained any other way other than signal modulation due to the POCO communication system?
forums.mikeholt.com
Click to expand...
If you mean smart meter, then yes.
 
winnie said:
Not just a smart meter, but a smart meter that uses a particular type of power line signalling.

Many smart meters use some sort of radio module for communication.
Click to expand...
I know they read the meters remotely and know if the meter has been pulled. Also, they can shut them off remotely, but that is for those who buy a certain amount of power on a pay as you go method. Kind of like prepaid cell phones, or prepaid debit cards. Don't know if they use the same meters for those or not.
 
I would be inclined to a FOP across the main breaker, then cycling it multiple times, with all loads off, then repeating the FOP. Using a known load before and after would help.

The starting of an AC unit causing noise would be normal IMO but checking that breaker as well wouldn't hurt a thing.
 
Little Bill said:
Had a guy call me to check out a hum and buzzing noise in the panel. The hum seemed to not be anything I would worry about as I've heard that before. However, when breaker for the air handler for the AC unit was turned off and back on, you could hear the buzzing/arcing sound.
I checked all the lugs and terminals for breakers and all were tight. There is an outside disconnect so I checked the lugs there and all was good.
Also had the POCO come and check their connections and all was good there.

The noise seemed to be coming from the main breaker. The panel is a SqD Homeline 200A main breaker. So I was going to contact them.

They also wanted me to change out some dimmers for regular switches as their LED lights would sometimes flicker badly when on the dimmer. The dimmers had been changed by me just a few weeks ago. But the guy said the lights started to flicker again. I told him the LED lights, which are the wafer recessed type lights, were probably not working right with the dimmers. The dimmers were 3-way and I didn't have any 3-way regular switches with me.
The guy said he would pick some up and change them out.

Here's the odd part.
He called me a while ago and said he got them changed. He says all the flickering, humming and buzzing have stopped. I knew the flickering would stop, but what would changing dimmers out for regular switches have to do with the arcing/buzzing sound coming from the panel?
I told him to keep an eye on it and listen for the arcing sound. I am not convinced that it has stopped!
Click to expand...
I have never hear/seen flickering lights and humming from the panel that stopped when changing out switches. What worries me is I have had panels that hum and its not any loose connection but a worn buss bar. In a lot of residential the panels are in the basement. If the basement is on the moist side the buss bars can corrode even thou the rest of the panel is fine. That is my experience and I am not a fan of noisy panels. I am concerned about fire risk.
 
The electrical install is only a few months old, so no corrosion on anything. This is a Church and the AC is the largest load. All heating is gas. I told the guy I expected the flickering of the lights to stop with removing the dimmers, but no way, that I know of, would that stop the buzzing/arcing sound when the AC unit came on. I expect to hear back after the building is used this weekend.
 
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