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Thread: Detached garage

  1. #1
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    Oct 2015
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    Detached garage

    Quick question for you experts I think III m right but just want to double check. I'm going to be running a sub panel in my buddys garage it's detached about 50' from main house. I'm going to be running an 1 ½ PVC pipe with 3 #6 AWG my question is because it's detached and a sub panel am I supposed to
    1. install a ground rod and isolated neutral. Or
    2.Run an egc from main panel to sub with isolated neutral

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  2. #2
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    Both a and b

    4 wires , isolate the neutral and drive 2 rods connected to the equipment grounding bar.

  3. #3
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    I agree with Dennis.

    2 hots, one grounded, one grounding

    If it is new construction then use the foundation rebar as the grounding electrode.
    Edward
    Education is a progressive discovery of our ignorance.


  4. #4
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    you need a grounded (neutral) conductor and an equipment grounding conductor, they must not tie together except back at wherever the service is. You must have a grounding electrode at a separate structure supplied by a feeder, it must connect to the equipment grounding conductor and not the grounded (neutral) conductor.

  5. #5
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    Code section for the above replies is 250.32(A) & (B).
    "Electricity is really just organized lightning." George Carlin


    Derek

  6. #6
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    Ty for all the replies

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  7. #7
    Join Date
    Sep 2011
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    columbus, ohio
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    Ground Rod?

    Quote Originally Posted by Dennis Alwon View Post
    Both a and b

    4 wires , isolate the neutral and drive 2 rods connected to the equipment grounding bar.
    250.32 (A) Grounding Electrode - Exception: Electrode not required.

    We wire detached garages all the time, we have always driven a ground rod. My inspector told me NOT to drive the ground rod, as that is forming a Second ground on the system.
    Thoughts?

  8. #8
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    Electrode is not required if you run a single circuit or a multiwire branch circuit however if you install a panel than a grounding electrode conductor is needed and it can be any of a few methods. Normally one dives 2 rods.

  9. #9
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    There is no need to drive a ground rod with one circuit however I don't believe it can hurt.

  10. #10
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    You can connect all the aux ground rods you want for whatever purpose at any building. They must connect to the equipment grounding conductor of whatever you are trying to supplement.

    Otherwise every building or structure needs it's own grounding electrode system connected at the main supply, and separately derived systems need a connection to the grounding electrode system of the building or structure they are a part of as well.

    There is an exception as mentioned in 250.32(A) but that is only for buildings or structure supplied by a branch circuit. You are not prohibited from installing GEC's at such structures, it just is not mandatory. One example where this is done quite frequently is at lighting poles.

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