2. tech-talk
  3. 126981-501

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 2 responses by erik_squires

erik_squires
15,691 posts
 
And please dear god tell me you've paid this much attention to your room acoustics???
erik_squires
15,691 posts
 
No, you won't have ground loops... it's just a little um, pointless. :)

So by NEC you must run a dedicated ground from your panel all the way to the box where your outlets are, and ground the outlet AND The box there. This is to ensure if a short occurs inside the box it is grounded and trips the appropriate breaker.

You ran a separate ground wire to the receptacle... which is kind of pointless. :)

Your friend is right, they will be bonded at the box, but they would be anyway. The problem is you wanted a separate ground but you won't have it. Probalby the easiest solution at the beginning would have been to use plastic outlet boxes.

You only have to worry about ground loops when you have different potentials. Like if you hooked up some equipment to one outlet, and other equipment to a second outlet that had significant resistance between the two grounds.

Best,


Erik
More to discover