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Grounding Metal Outlet Boxes and Isolated Ground Receptacles

Just installed six really nice separate dedicated 20 amp lines (with 6 awg) for my new dedicated listening room.  Decided to use heavy metal outlet boxes so that I could make my six Furutech Receptacles as strong and sturdy as possible.  I also had my electrician run 4-wire 6 agw to the boxes so that we could have one ground wire to the metal receptacle box and then a separate ground wire to the isolated ground screw on the Furutech.

I sent some photos of the setup to a friend of mine (who just happens to be an electrical engineer) and he raised an the issue that since my Furutech Receptacles are metal and they will be screwed into the metal box with metal screws, then we have effectively now tied the two separate grounds together!  Help!  Is that a bad idea?   Is having the box and receptacle setup in this way going to cause issues once my gear is in place; ground loop hums, etc?






stickman451

Showing 1 response by gs5556

gs5556
1,245 posts
 
What concern did the engineer express? The way you describe is legal except for patient care areas where the two ground paths must be separate. (Maybe that's his thinking).

Your chances for a ground loop are not from the two ground paths but from plugging in separates into different outlets. If you have an amp on one outlet, a preamp in another, a DAC in another and a transport in another still, each component has four separate ground paths when the interconnects are installed. Any unbalance in the neutrals may induce a ground loop hum, especially if the grounding conductors back to the panel are of different lengths.
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