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

  1. #81
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    Oct 2009
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    Quote Originally Posted by Daniel malack View Post
    If you are interpreting the word " isolated " as not being conducted. just stick the ground out side the panel and let it hang in free air! Then it would surely be isolated.

    The confusion is in the what the installer defines as "isolated" .

    If you have an isolated grounding receptacle you attach it to the isolated screw on the receptacle and don't attach it to anything all the way back to main panel ground.
    That would be isolated but it wouldn't be a ground.

    I understand how this stuff works. The confusion comes from the idea that there can be two grounds which are absolutely isolated from each other.

  2. #82
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    May 2012
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    Amissville, Virginia USA
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    Quote Originally Posted by ggunn View Post
    That would be isolated but it wouldn't be a ground.

    I understand how this stuff works. The confusion comes from the idea that there can be two grounds which are absolutely isolated from each other.
    It's real simple. It's isolated for what is going on in the branch circuits. If you isolate the ground at main , other faults won't effect this isolated ground ckt. I believe all isolated ckts are dedicated. You can't isolate it by driving a separate ground rod, uffer, bldg steel, ground ring etc.. you would never get the breaker to trip by running a separate electrode.

    Sent from my SM-T350 using Tapatalk

  3. #83
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    deleted

  4. #84
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    Quote Originally Posted by Daniel malack View Post
    ... You can't isolate it by driving a separate ground rod, uffer, bldg steel, ground ring etc..
    It is also a violation of 250.50.
    I will have achieved my life's goal if I die with a smile on my face.

  5. #85
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    May 2012
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    Quote Originally Posted by Smart $ View Post
    It is also a violation of 250.50.
    Correct. Using a definition of isolated to the extreme would be let it hang outside the panel in free air. Correct isolation is all the way back to the main. If a fault to ground occurs anywhere in the building it won't effect this isolated ckt. Electrons won't back up and go away from source and effect isolated equipment. If you ground every single conduit, box, and fixture. then if a fault to ground occurs it will take path of least resistance, if through sensitive equipment, it will. That is isolated Ground! It is isolated from other effects on the electrical system.

    Sent from my SM-T350 using Tapatalk

  6. #86
    Join Date
    Jun 2015
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    nyc
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    Quote Originally Posted by Daniel malack View Post
    Correct. Using a definition of isolated to the extreme would be let it hang outside the panel in free air. Correct isolation is all the way back to the main. If a fault to ground occurs anywhere in the building it won't effect this isolated ckt. Electrons won't back up and go away from source and effect isolated equipment. If you ground every single conduit, box, and fixture. then if a fault to ground occurs it will take path of least resistance, if through sensitive equipment, it will. That is isolated Ground! It is isolated from other effects on the electrical system.

    Sent from my SM-T350 using Tapatalk
    in my opinion, the "extreme" solution is to install transformer and connect to it all equipment required IG grounding.

    Sent from my Nexus 5X using Tapatalk

  7. #87
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    Jun 2003
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    Hawthorne, New York NEC: 2014
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    Well no. The ground(s) and the secondary side grounded conductor still have to be connected to the the service. You can't have an isolation transformer with the secondary floating.

    There are isolation transformers that are designed to supply "technical power" that have a center tapped secondary. 60-0-60. But the center tap has to be connected to the service ground.

    -Hal

  8. #88
    Join Date
    Aug 2017
    Location
    Los Angeles CA
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    What cracks me up are the few contractors and consumer boards that install isolated ground circuits in residential for computers and more complex AV systems!

    Think about it...

    The box (metal or plastic) is attached to a wooden stud. The cable is no doubt Romex and this is always a dedicated circuit. So even a straight installation is in fact the same electrically as an isolated ground in this case. If a cheap receptacle bothers you then just use a spec grade. No need for IG.

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