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Grounding Electrode Conductor Sizing and Means of Attachment

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    Grounding Electrode Conductor Sizing and Means of Attachment

    I'm installing a 1000 amp service, and I plan on using ground rods and the water main for my grounding electrode system. I'm using 4x parallel 250 kcmil per phase. According to Table 250.66, I'd be looking at a 2/0 grounding electrode conductor, if I'm not mistaken. My question is, how do I go about attaching such a large conductor to the ground rods and water main? I asked my electrical supplier and they didn't have a quick answer, which makes me wonder if I've sized the conductor wrong. Also, do I need larger ground rods for such a large conductor?

    #2
    The Code provides maximum sizes for GEC connecting ground rods. No problem there. I believe also an upper limit on size for GEC to water main.

    Comment


      #3
      I don't know how to do the attachments. Someone else will have to answer that question. But you only need a #6 for the connections to ground rods. Reference 250.66(A). Welcome to the forum.
      Charles E. Beck, P.E., Seattle
      Comments based on 2017 NEC unless otherwise noted.

      Comment


        #4
        Zander are you licensed or are you working for a licensed person?
        They say I shot a man named Gray and took his wife to Italy
        She inherited a million bucks and when she died it came to me
        I can't help it if I'm lucky

        Comment


          #5
          Thanks for the responses! GoldDigger, from what I've read, the upper limit on the GEC to the water main is Table 250.66. Over 1100 kcmil is 3/0 copper. Sky's the limit for the size of largest ungrounded service conductor. Dennis Alwon, I am the licensed person. charlie b, I'm familiar with 250.66(A). What generates some confusion on that one is that around here, for whatever reason, inspectors and electricians alike seem to thing you need #4 copper to the ground rods, even for a single-phase 200 amp service. I didn't know if there was something tucked away in the code that would make you bump it up depending on what other electrodes make up the system. Thanks for the answers so far. Keep em coming!

          Comment


            #6
            #3/0 is the largest GEC ever required. A #6 to the ground rod electrodes and you're done. Wondering why if you have a 1000 amp service that you don't have a CEE?
            Rob

            Moderator

            All responses based on the 2017 NEC unless otherwise noted

            Comment


              #7
              Connector like we use.
              https://m.platt.com/Products.aspx?pid=756059

              not sure why you want it, but...

              Comment


                #8
                CEE?

                Comment


                  #9
                  Hv&Lv what do you mean, "not sure why you want it?"

                  Comment


                    #10
                    Originally posted by zander View Post
                    CEE?
                    Concrete encased electrode

                    Comment


                      #11
                      Originally posted by zander View Post
                      Hv&Lv what do you mean, "not sure why you want it?"
                      Charlie b, & infinity have referenced 250.66(a).
                      it says #6 is all you need, as long as your using an 8’ rod or approved plate.

                      maybe I’m missing something in your post?

                      250.66(A) Connections to Rod, Pipe, or Plate Electrodes.

                      Where the grounding electrode conductor is connected to rod, pipe, or plate electrodes as permitted in 250.52(A)(5) or (A)(7), that portion of the conductor that is the sole connection to the grounding electrode shall not be required to be larger than 6 AWG copper wire or 4 AWG aluminum wire.

                      Comment


                        #12
                        Wondering why if you have a 1000 amp service that you don't have a CEE?
                        Infinity, I wish I did. This is old construction. Got bought by a small printery. It has a 200 amp single phase service currently. It's a glorified pole barn with a concrete slab. No rebars exposed though. That was back before they did such things.
                        Last edited by zander; 09-13-19, 11:38 PM.

                        Comment


                          #13
                          I hope I’m corrected here if I’m wrong.
                          I may be missing something in your post with what’s in my head.

                          your installing a 1000 amp service.
                          Bring your 3/0 GEC and terminate it in the CT cabinet
                          Water line(10’ or more as electrode) #2.
                          supplement with a rod, #6 to the rod.

                          Comment


                            #14
                            Hv&Lv I'm not following. I'm looking at Table 250.66 and see that the largest GEC that I need is a 2/0. What would I be bringing a 3/0 from to terminate in the CT cabinet? How is the GEC from the water line not based on Table 250.66 and should be a 2/0?

                            Comment


                              #15
                              How do you arrive at #2 for the water line?

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