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Hum in Speakers with New Dedicated 20 amp Circuit

I just ran some 12-2 from a new 20 amp breaker and installed a dedicated outlet for my system. Now I get a very audible hum in both channels. If I switch back to the shared 15 amp outlet, no hum. I checked the new outlet with a tester and it checks out as wired correctly. At the electrical box, the black wire is connected to the breaker and the white and ground are attached to the same ground strip. I’m using a 20 amp receptacle.

Anyone with thoughts on how to resolve?

mjjw
erik_squires
15,657 posts
 

Looking at the picture, the ground and neutral from upstream were wired to the bus on the right.

If an electrician did this, get a new one.

ieales's avatar
ieales
1,201 posts
 

I color coded it. Yellow is the coming wire. Black hot. White is neutral. Green is ground.

 

Forget the color-coding. Competent electrical people can figure it out with a simple text label.

 

This is how it should be done.

 

And just what do have that requires 20A continuous / 200A peak?

Post removed 
mjjw OP
8 posts
 

NB: I didn’t install the sub panel; I just added an additional breaker.  The sub panel has been in for almost a decade.  I have an electrician look it all over and correct as necessary.  Thanks all.

tkhill's avatar
tkhill
80 posts
 

Call a licensed electrician. My brother, the E.R. nurse, makes his living off of amateur electricians and guys whose last words were "Hold my beer and watch this".

Make sure the sparky who comes to your home is the license holder & not an unsupervised apprentice or journeyman, as is often the case here in D.C.

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