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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
guamie
12 posts
 

Separate the grounds and the neutral. Ground to the left side bar and the neutral to the right side bar. I'm an electrician and get called a lot for these corrections. 

mastering92
870 posts
 

Great, it works! 

jea48
4,277 posts
 

EDIT:

Jea48 said:

I assume the sub panel was install because the main panel was full. Three 120V circuits were moved from the main panel to the new sub panel. I assume, hopefully, to free up two breaker spaces in the main panel for a 2 pole breaker to feed the sub panel.

Add.  Evidence would be a two pole breaker in the main panel that feeds the sub panel. Might even be marked on the panel schedule.

erik_squires
15,673 posts
 

 

One equipment grounding conductor. (Note: If a steel conduit is used between the main panel and sub panel that meets NEC for use as an equipment grounding conductor.)

That's a surprise! We can't do this for junction boxes or outlets.

ieales's avatar
ieales
1,201 posts
 

I haven’t checked the code in a while, but I think it’s because a panel is more or less permanent.

With an outlet, if it’s out of the box, no earth. Gotta protect the unskilled from themselves.

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