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Thread: Grounds per Conduit

  1. #1
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    Grounds per Conduit

    Quick question here- We've got plans that call for one #2 EGC per conduit carrying 2 700KCmil circuits- it's my understanding that we would need one ground per circuit in this case, or to at least upsize the single ground. Is this correct or will one #2 EGC be sufficient?

  2. #2
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    Take a look at 250.122(C).
    Don, Illinois
    The code only applies to T&M work....it does not apply to contract work.

  3. #3
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    I am not sure I understand the question. If you put conductors associated with two or more circuits in the same conduit, they can share a single EGC, so long as that one EGC is sized for the highest rated circuit. But if you are asking whether a #2 EGC is big enough for the circuits in your question, we can't answer that without knowing the circuit breaker rating (this is the basis for sizing the EGC) and the minimum required ampacity of the conductors (this will tell us whether the conductors were upsized, which would require the EGC to also be upsized - per the code article that Don cited).
    Charles E. Beck, P.E., Seattle
    Comments based on 2014 NEC unless otherwise noted.

  4. #4
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    you wouldnt be able to fit 2 sets of 700kcmil conductors in the same raceway... I think if its just simply 2 700kcmil conductors the engineer may have been doing this to make it fit in the conduit using a more advanced analysis of the conduit interior space, thinking splitting the egc conductors into two sets would make it easier to pull

  5. #5
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    Quote Originally Posted by 310 BLAZE IT View Post
    you wouldnt be able to fit 2 sets of 700kcmil conductors in the same raceway... I think if its just simply 2 700kcmil conductors the engineer may have been doing this to make it fit in the conduit using a more advanced analysis of the conduit interior space, thinking splitting the egc conductors into two sets would make it easier to pull
    If you have two circuits in the same raceway then you only have to have a single EGC sized to the larger OCPD of the two circuits, but if you have the two circuits in separate raceways each has to have an EGC sized to the circuit in the raceway.

  6. #6
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    Quote Originally Posted by OneSunGuy View Post
    Quick question here- We've got plans that call for one #2 EGC per conduit carrying 2 700KCmil circuits- it's my understanding that we would need one ground per circuit in this case, or to at least upsize the single ground. Is this correct or will one #2 EGC be sufficient?
    As mentioned look at 250.122.

    If these "700kcmil circuits" are protected by a 500 amp or less OCPD - it is good.

    If they are parallel conductors and an even larger OCPD, 2 AWG is too small for 250.122.

    #2 could also be too small if the 700's are increased in size for voltage drop reasons even though the OCPD is under 500.

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