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    The word or

    Nec 2014 Article 250.64(D) says multiple service disconnecting means grounding electrode connection can be following 250.64(D)(1), 250.64(D)(2) OR 250.64(D)(3).

    What does the word OR mean in the code for 250.64. The question is does the Word OR mean one cannot install GECs at more then one location? So one cannot install 250.64(D)(2) option as well as 250.64(D)(3) option in same install. One has to chose either one of (D)(1), D(2), D(3) but they cannot be mix in same install?

    #2
    In common English, OR is interpreted to mean at least one of the alternatives, not the exclusive OR (XOR) of logic which means exactly one of the alternatives. You are overthinking this question.

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      #3
      Originally posted by hhsting View Post
      Nec 2014 Article 250.64(D) says multiple service disconnecting means grounding electrode connection can be following 250.64(D)(1), 250.64(D)(2) OR 250.64(D)(3).

      What does the word OR mean in the code for 250.64. The question is does the Word OR mean one cannot install GECs at more then one location? So one cannot install 250.64(D)(2) option as well as 250.64(D)(3) option in same install. One has to chose either one of (D)(1), D(2), D(3) but they cannot be mix in same install?
      Yes I think you choose one of
      250.64 (D)(1) Common Grounding Electrode Conductor sized based on T250.66 (and Note 1 the largest sum of the areas of the corresponding conductors of each set). This gets interesting if you just have 2 groundrods, the 'Common Grounding Electrode Conductor' seems like it is sized per 250.66(A) & 250.64(F) only requiring a #6 CU no matter what, and then you would have taps sized for each disco's ungrounded conductors.
      OR
      250.64 D(2) Individual Grounding Electrode Conductors from each disco to the grounding electrode system,
      OR
      250.64 D(3) A neutral Buss or tap block in a service wireway connected to the grounded service conductor and GEC (most common way I see it)

      I would be curious how you were thinking of mixing them?
      Comments based on 2017 NEC unless otherwise noted.

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        #4
        It's the lack of the Serial Comma that causes confusion!

        There was a dairy in Maine that found out the importance of that extra comma! https://www.nytimes.com/2017/03/16/u...a-lawsuit.html

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