Electric panel 60 cycle hum - Battery charger

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  #1  
Old 11-07-13, 06:41 AM
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Electric panel 60 cycle hum - Battery charger

When I have my drills battery charger plugged in (24V) I can hear a 60 cycle type hum at the charger.

What concerns me is that I also hear the same 60 cycle hum at the electric panel in the other room.

This only occurs when the battery is charging. When the charger doesnt have battery plugged in no noise. I also tested the same outlet/circuit with other loads besides a battery charger and there is no hum.

Is this something I should worry about?
 
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  #2  
Old 11-07-13, 08:32 AM
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The hum at the panel may indicate a connection that isn't as tight as it should be. You can turn the main breaker off, uncover the panel, and snug up the terminal screw on each breaker.

Don't over-tighten them because that cam damage the conductor. Look for a torque value on the label on the inside of the panel door. Just s decent tightening with a screwdriver is all they need.

If that doesn't cure it, post back and we'll look further.
 
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Old 11-07-13, 10:36 AM
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I wiggled the breaker a bit and there was slight difference in resonance of the hum. With the circuit off there is no hum.

So I changed the breaker and there is still hum with the new breaker just maybe to a little lesser extent.

Its not an arcing noise, I liken it to what a ballast sounds like but not as loud. Like the sound a small transformer makes.

It goes away immediately when the battery is removed from the charger and it does not occur with any other load plugged into that outlet/circuit.

But if I plug this charger into different circuits it does not make noise on them....
 
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Old 11-07-13, 10:55 AM
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Im even more confused. I put in a heavy load space heater with a thermostat. Every time it cycle on I hear a slight difference in the resonance in the panel....

Is it normal to hear 60 cycle hum in panel as loads are applied?

I moved the heater around the house and with my ear directly on the panel, I can hear when it turns on and off. Samething with my microwave on a totally different circuit, with my ear on the panel, I can tell when it starts and stops.

This is not a loud or what I would consider an arcing sound... its an electrical 60 cycle sound if that makes any sense>?>
 

Last edited by zmike; 11-07-13 at 11:22 AM.
  #5  
Old 11-07-13, 01:50 PM
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I would say that while not common neither is it abnormal. I AM intrigued by it only humming when that particular battery charger is in use. I suspect that the charger is setting up a resonant circuit with the magnetic component of the circuit breaker. I doubt that it is anything to lose sleep over.
 
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Old 11-07-13, 02:48 PM
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Its got me kinda freaked out. Although I can only hear the charger when plugged into the circuit I swapped breakers, Ive been plugging different loads in around the house on different circuits too.

I can say for sure, with my ear directly on the panel cover, I can hear what I can describe as 60hz magnetic field. When different loads are applied the resonance is different.

Not just on one circuit either for example a toaster on one circuit or a 1500 watt space heater on another.

If I stand back 2 feet I dont hear anything.

So I still wonder, do you think actually "hearing" a hum with loads being applied an abnormal thing.... do you hear this at your panel?

PS- You might think I am nuts after reading this, well maybe a little bit!
 
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Old 11-07-13, 03:00 PM
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I wrote that the hum is NOT abnormal. Yes, I can hear a hum from my panel under certain conditions.
 
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Old 11-07-13, 03:14 PM
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I see, thank you Furd... in fact further testing reveals that the battery charger (65W to 24DC) cause the hum on other circuits as well. So in general I have multiple circuits "humming" when loads are applied.

SO when you say "certain conditions"... when do you experience "hum"?
 
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Old 11-08-13, 06:30 AM
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ANother thing I noticed on some of the loads I am testing.

If I put my hand on the panel cover, as to dampen it, the noise stops sometimes or changes resonance. THat indicates vibration.

All of these occurences I have to have my ear directly on the panel cover to hear the "hum".
 
  #10  
Old 11-09-13, 04:41 AM
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Circuit breakers use a combination of thermal and magnetic properties to "trip" on overload and short circuit. Sometimes the parts inside the plastic case will vibrate a bit creating the hum. It is not considered a defect and there is no reason to be overly concerned unless it is making a LARGE amount of noise.
 
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Old 11-10-13, 11:55 AM
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Thanks Furd!

Back to the original inquiry about the 24v battery charger.

After I realized it caused the buzz/hum in the panel on every circuit in my house. I took it over to a friends house and sure enough, it made an audible buzz/hum at his panel as well!!!

So what is likely happening here? Charger faulty? Or is this normal with transformers (sure they hum at the point of plugging in, but a 100 feet away in the panel as well?)
 
  #12  
Old 11-11-13, 01:11 AM
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I suppose I could try to make up some BS story of why it buzzes but I suspect you would rather have the truthful answer which is, I don't know why it buzzes.
 
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