Noise in receptacle circuit

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Ravenvalor

Ravenvalor

Senior Member
Location
Triad region of NC
Occupation
Electrician
I have a customer who has a humming noise coming from her wall or floor behind her bed. The noise stops when I turn off the receptacle circuit which runs in the wall behind the bed and feeds the receptacles in that room. It is a 3-wire cable with one conductor being switched from the wall switch. The switched conductor feeds half of each receptacle in the room. I unplugged all of the appliances plugged into those receptacles but to no avail. She did not want me to dig into the problem because I had already been there for a while on other projects. Does anyone have a suggestion or two? I have never heard humming noise coming from a cable except for ceiling fan switch legs.

Thank you,
Jim
 
Turn the circuit off, then locate everything on it by finding everything that doesn't work. Then unplug everything on the circuit.

My guess is, there's something (like a radio or a wall wart) in the other room.
 
I second what 480 said, and would also look for a doorbell transformer that is most likely on that same circuit, as the vibrations can travel quite a way from the actual transformer location.
 
Ravenvalor said:
Thanks for the replies. I have tried those suggestions and have found nothing. I will give it another shot though.
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Start breaking the circuit in halves.... divide and conquer.

Find the (roughly) middle of the circuit, and take it apart. if the problem persists, it's between there and the panel. If it goes away, start looking downstream. Keep taking the portion you're searching in and dividing it in half.

You'll eventually isolate the one component that's involved with the problem.
 
480sparky said:
Start breaking the circuit in halves.... divide and conquer.
Click to expand...
Just before you do that (and yes, divide and conquer, or to give it the proper name, "the binary chop" is one of the most effective and fastest troubleshooting techniques) I'd do one other test.

Since everyone is convinced theres nothing on that circuit, lift the hot wire off the breaker and measure resistance hot wire to neutral bar. If its not infinite then there is something on the circuit somewhere, so one more trip round the home trying to find what else that breaker feeds may solve the mystery.

If it doesn't: binary chop should find it fast.
 
dbuckley said:
.......(and yes, divide and conquer, or to give it the proper name, "the binary chop" is one of the most effective and fastest troubleshooting techniques) .............
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"Binary Chop" would likely get the deer-in-the-headlights look from most customers.

"Divide and conquer" makes it sound like you know what you're doing! :D
 
Sound can be deceptive you think its coming from one area but its not I had a call for the same thing she turned off all the power and she could still hear it ended up being a computer ups
 
There have been similar threads in the forum about this, eventually finding the cause to be everything from electric toothbrushes to adult toys.
 
divide

divide

480sparky said:
Start breaking the circuit in halves.... divide and conquer.

Find the (roughly) middle of the circuit, and take it apart. if the problem persists, it's between there and the panel. If it goes away, start looking downstream. Keep taking the portion you're searching in and dividing it in half.

You'll eventually isolate the one component that's involved with the problem.
Click to expand...


This is how I usually solve problems but the customer did not want to spend the $. It's their problem not mine. Thanks for the replies.
 
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