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Thread: This is not how you do isolated ground ....

  1. #1
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    This is not how you do isolated ground ....

    I've seen this at least a dozen times now.

    This is a restaurant we're gutting and remodeling. Many years ago this particular brand starting requiring IG for all POS equipment, and they required existing stores to have new panels put in for the IG receps.

    This is one such install.







    IG grounding conductor goes straight to a ground rod. We're going to take both the Eaton and Siemens panels out, add a new NQ panelboard for equipment and a QO loadcenter for the IG.


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  2. #2
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    "Isolated" and "ground" seem oxymoronic to me. There is only one ground.

  3. #3
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    Wow. That is one way to do it.....
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  4. #4
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    Quote Originally Posted by electrofelon View Post
    Wow. That is one way to do it.....
    And a creative one at that. (How did it ever pass inspection? Or was it inspected at all?)

  5. #5
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    Quote Originally Posted by ggunn View Post
    "Isolated" and "ground" seem oxymoronic to me. There is only one ground.
    This particular brand is hardcore about having the IG on POS equipment. We always have to sign an affidavit at the end of the job to say it's correct and to their specs. We'll end up with about 50 receps total in 4000 sq ft of restaurant.

    Most others have moved away from it, as it is really no longer needed with modern equipment. A couple of other restaurant brands we build also require it, but not to the level of the store pictured above.


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  6. #6
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    Quote Originally Posted by brantmacga View Post
    This particular brand is hardcore about having the IG on POS equipment. We always have to sign an affidavit at the end of the job to say it's correct and to their specs. We'll end up with about 50 receps total in 4000 sq ft of restaurant.

    Most others have moved away from it, as it is really no longer needed with modern equipment. A couple of other restaurant brands we build also require it, but not to the level of the store pictured above.


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    wow. failed to grasp the concept, eh?

    the reason you want an isolated ground back to
    the MAIN ground bus is to prevent ground loops,
    that might bias solid state devices and cause madness.

    but grounding all the devices to a point completely
    different than the service ground virtually guarantees
    a ground loop.

    you can't fix stupid.
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  7. #7
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    I only wonder why in 2017 people are still specifying IG systems.
    Rob

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    All responses based on the 2014 NEC unless otherwise noted

  8. #8
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    Quote Originally Posted by Fulthrotl View Post
    wow. failed to grasp the concept, eh?

    the reason you want an isolated ground back to
    the MAIN ground bus is to prevent ground loops,
    that might bias solid state devices and cause madness.

    but grounding all the devices to a point completely
    different than the service ground virtually guarantees
    a ground loop.

    you can't fix stupid.
    Personally, I'd be more concerned about not having a proper ground fault current path and the potential for someone to get shocked, then I would be about ground loops.

  9. #9
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    Quote Originally Posted by Cow View Post
    Personally, I'd be more concerned about not having a proper ground fault current path and the potential for someone to get shocked, then I would be about ground loops.
    I agree, it might be marginally better than this gem that I found in a Post office. Guess that they couldn't get to the earth from the third floor.

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    Last edited by infinity; 08-09-17 at 08:13 PM. Reason: Spelling
    Rob

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  10. #10
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    Quote Originally Posted by Cow View Post
    Personally, I'd be more concerned about not having a proper ground fault current path and the potential for someone to get shocked, then I would be about ground loops.
    absolutely correct, but shouldn't we be concerned about the cow not giving milk here?

    Moooooooo......
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