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    SDS Grounding

    Hey Guys,

    In the attached 3 three line I have bonded N-G on the first disconnecting means on both the primary and the secondary of the T/F to earth and connected the transformers G to earth as well. I followed NEC 230.30(A)(1) Exception No. 2, but just a doubt if the "first disconnecting means" just denotes that it should be bonded either on the primary or on the secondary or should it be on the both disconnecting means. Is there any other code that stated this?

    Click image for larger version

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    Thanks

    #2
    You'll want to isolate the N from the G after the first disconnect. In the diagram the G appears to be redundant to the N

    Comment


      #3
      Originally posted by Buck Parrish View Post
      You'll want to isolate the N from the G after the first disconnect. In the diagram the G appears to be redundant to the N
      Do you mean on the 1000A disconnect? It is basically an EGC that goes till the 89L and at 89L it is terminated before going into the POCC

      Comment


        #4
        Originally posted by TheElectrician View Post
        Hey Guys,

        In the attached 3 three line I have bonded N-G on the first disconnecting means on both the primary and the secondary of the T/F to earth and connected the transformers G to earth as well. I followed NEC 230.30(A)(1) Exception No. 2, but just a doubt if the "first disconnecting means" just denotes that it should be bonded either on the primary or on the secondary or should it be on the both disconnecting means. Is there any other code that stated this?

        [ATTACH=CONFIG]23338[/ATTACH]


        Thanks
        Also, Do we have to ground "Earth" where ever we have a N-G bonding as showed in the diagram as I see a lot of posts talking:

        "he GEC connection and the SBJ can be... and it is required that they both be in the same enclosure." Post #4 - https://forums.mikeholt.com/showthread.php?t=183483
        "The GEC connection is to be made at the same point as the bonding jumper is made at, not where the EGCs are connected" Post #6 & #7 - https://forums.mikeholt.com/showthread.php?t=56753

        Which code says this?

        Comment


          #5
          That appears to be a wye-wye which would NOT be an SDS (if connected the way I think it is).

          Edit: in other words, there should not be a N-G bond.
          Ethan Brush - East West Electric. NY, WA. MA

          "You can't generalize"

          Comment


            #6
            Originally posted by electrofelon View Post
            That appears to be a wye-wye which would NOT be an SDS (if connected the way I think it is).

            Edit: in other words, there should not be a N-G bond.
            So,

            1) I should bond the N-G at the 89L disconnect (Primary side of the transformer), and should not bond in the 52IT (Secondary side of the transformer) because I can bond at the source or the disconnecting means but not at both the disconnecting means on primary and secondary is that right?
            2) When does the exception 250.30(A)(1) Exception 2 apply? If this is a behind the meter connection, does it apply since we are powering a building?
            3) I earth the system at 52IT and since the same wire goes via T/F I dont need to earth the T/F separately but I can bond ground to case in the T/F to continue the EGC, and also I have to earth the 89L because it is on the secondary of the T/F (and forms a new system basically)

            Correct me if im wrong.

            Comment


              #7
              Originally posted by electrofelon View Post
              That appears to be a wye-wye which would NOT be an SDS (if connected the way I think it is).

              Edit: in other words, there should not be a N-G bond.
              If the neutrals on both sides of the transformer are not bonded (to each other) I'm pretty sure it's separately derived.

              Comment


                #8
                Originally posted by ggunn View Post
                If the neutrals on both sides of the transformer are not bonded I'm pretty sure it's separately derived.
                I agree. I can't tell from the drawing if they are common.
                Ethan Brush - East West Electric. NY, WA. MA

                "You can't generalize"

                Comment


                  #9
                  Originally posted by electrofelon View Post
                  I agree. I can't tell from the drawing if they are common.
                  Yeah, the drawing is pretty fuzzy when I try to make it bigger. It sort of looks like one of the phases is bonded on both sides, but that can't be right.

                  Comment


                    #10
                    Originally posted by electrofelon View Post
                    I agree. I can't tell from the drawing if they are common.
                    Originally posted by ggunn View Post
                    Yeah, the drawing is pretty fuzzy when I try to make it bigger. It sort of looks like one of the phases is bonded on both sides, but that can't be right.
                    I have attached the pdf let me know if this gives a better idea.
                    Attached Files

                    Comment


                      #11
                      Originally posted by ggunn View Post
                      Yeah, the drawing is pretty fuzzy when I try to make it bigger. It sort of looks like one of the phases is bonded on both sides, but that can't be right.
                      We touched on wye-wye recently in another thread, and although I have never really bought any of the reasons people throw out there, there seems to be thinking that bonding the two neutrals together is a good thing, hence why I jumped to the conclusion that they were intended to be bonded. Hopefully OP can clarify.
                      Ethan Brush - East West Electric. NY, WA. MA

                      "You can't generalize"

                      Comment


                        #12
                        Originally posted by electrofelon View Post
                        We touched on wye-wye recently in another thread, and although I have never really bought any of the reasons people throw out there, there seems to be thinking that bonding the two neutrals together is a good thing, hence why I jumped to the conclusion that they were intended to be bonded. Hopefully OP can clarify.
                        If you see the PDF attached, I have bonded the neutral on both the sides because 250.30(A)(1)(b) says, "where the system bonding jumper is installed at the first disconnecting means of a separately derived system (T/F), the system bonding jumper must connect the neutral conductor of the derived system to the metal disconnecting means enclosure" - Mike Holt NEC 2014 Solar Photovoltaic Systems book.

                        Which I interpreted as the first disconnecting means on both primary and secondary side.

                        Comment


                          #13
                          Originally posted by TheElectrician View Post
                          If you see the PDF attached, I have bonded the neutral on both the sides because 250.30(A)(1)(b) says, "where the system bonding jumper is installed at the first disconnecting means of a separately derived system (T/F), the system bonding jumper must connect the neutral conductor of the derived system to the metal disconnecting means enclosure" - Mike Holt NEC 2014 Solar Photovoltaic Systems book.

                          Which I interpreted as the first disconnecting means on both primary and secondary side.
                          You only bod N-G on the secondary side
                          Ethan Brush - East West Electric. NY, WA. MA

                          "You can't generalize"

                          Comment


                            #14
                            Originally posted by TheElectrician View Post
                            If you see the PDF attached, I have bonded the neutral on both the sides because 250.30(A)(1)(b) says, "where the system bonding jumper is installed at the first disconnecting means of a separately derived system (T/F), the system bonding jumper must connect the neutral conductor of the derived system to the metal disconnecting means enclosure" - Mike Holt NEC 2014 Solar Photovoltaic Systems book.

                            Which I interpreted as the first disconnecting means on both primary and secondary side.
                            The derived neutral is in the secondary of your transformer and there is no electrical connection to the primary unless you make one, and generally this is not done.
                            If Billy Idol is on your playlist go reevaluate your life.

                            Comment


                              #15
                              Originally posted by electrofelon View Post
                              You only bod N-G on the secondary side

                              It's correct that 250.30(A)(1) is only about the secondary side. But here's a loaded question:

                              Is 89L a service disconnect? If so then the N-G bond there is correct.

                              [MENTION=159145]TheElectrician[/MENTION]
                              We are not going to decide that question here, although you've got it drawn like it is a service disconnect. But you and the AHJ must be on the same page. Let us know if you need references to past threads on the forum.

                              Comment

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