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Thread: NEC and Earthing Conductors

  1. #1
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    Sep 2009
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    NEC and Earthing Conductors

    Hello Everybody,

    I just want to ask for NEC Code Reference for whether the following is legal or not as per NEC:

    1- Pulling Earthing conductors in a conduit different from Phase and Neutral Conduit (example: pulling 4x300 mm2 in one conduit and pulling the 1 x 150 mm2 earthing conductor in seperate conduit) Please provide NEC reference

    2- When installing parallel Run Feeders, is it legal to put only single earth for parallel phase and Neutral conductors? (example pulling 2x(4x 300) and pulling only single 1x150 mm2 for both feeders) Please provide NEC code reference.

    Thank you

  2. #2
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    See 310.4 (C) and (E).

  3. #3
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    Also see 300.3(B)
    Instructor, Industry Advocate

  4. #4
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    Feb 2003
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    Illinois
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    Assuming that "earthing conductor" = Equipment Grounding Conductor, you need to look at 250.122(F) for the parallel installation.
    Don, Illinois
    "It is the first responsibility of every citizen to question authority." B Franklin

  5. #5
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    Sep 2009
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    Details

    Can you explain more details? the conclusion (legal or not legal for two issues)?

    I couldn't understand the content well..

  6. #6
    Join Date
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    Quote Originally Posted by safigh View Post
    Can you explain more details? the conclusion (legal or not legal for two issues)?

    I couldn't understand the content well..
    300.3(B) says all of the conductors of a circuit, including the equipment (EGC)grounding conductor (earthing conductor) must be contained within the same raceway or cable, so the answer for item 1 is...you are not permitted to do that by the NEC rules.
    300.3(B) also applies to the parallel installation ...you need an EGC with each set of paralleled conductors. In addition the rule in 250.22(F) requires that the EGC be sized per the feeder overcurrent protective device and that it be "full size" in each run.
    Don, Illinois
    "It is the first responsibility of every citizen to question authority." B Franklin

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