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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
jea48
4,277 posts
 

@mjjw

It’s an easy fix for a licensed electrician.

Replace the bare Aluminum neutral conductor with an insulated #2 AL conductor. (Code required for a sub panel)

Install a new #8 copper green insulated equipment grounding conductor. He will terminate it on the ground bar in the sub panel. (Could be #8 bare solid but stranded is easier to work with. He’ll use a piece of green stranded #8cu insulated wire.

Move the equipment ground wires from the neutral bar to the equipment ground bar. (Extend wires as needed)

I would have the electrician check the System Ground, Grounding Electrode System, (Electrical Service connection to Mother Earth), to make sure it meets the code for your city.

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Post removed 
jea48
4,277 posts
 

Replace the bare Aluminum neutral conductor with an insulated #2 AL conductor. (Code required for a sub panel)

Edit for clarification:

Replace the bare Aluminum neutral conductor with an insulated conductor.

(Code required for a sub panel)

#2 AL size for the 100A feeder that feeds the sub panel. (sized per NEC)

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