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    Is this Grounding Diagram correct?

    Is this diagram correct? #6 feels way to small for bonding the building's metal pipping. Circuits over 200amps are existing the main SWBD.

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    Our comedian shamelessly joked about a blackout. Talk about dark humor.

    #2
    Yes and no. Per 250.66(A), if you are only connecting to rods, pipes, or plates, and there is not a different type of electrode further downstream, then #6 copper is sufficient. That is the "yes" part. The "no" part is that the grounding electrode conductors need to be attached to the neutral bus, not the equipment ground bus. I know that they are bonded together, but right is right nonetheless.
    Charles E. Beck, P.E., Seattle
    Comments based on 2017 NEC unless otherwise noted.

    Comment


      #3
      Originally posted by charlie b View Post
      Yes and no. Per 250.66(A), if you are only connecting to rods, pipes, or plates, and there is not a different type of electrode further downstream, then #6 copper is sufficient. That is the "yes" part. The "no" part is that the grounding electrode conductors need to be attached to the neutral bus, not the equipment ground bus. I know that they are bonded together, but right is right nonetheless.
      Thanks

      But- help my understand why code says its ok:

      1) The gas pipe is technically a grounding electrode as metal gas mains can run the entire town.

      2) A 600amp circuit could energize the fire sprinkler pipping as much as a 200amp circuit.
      Our comedian shamelessly joked about a blackout. Talk about dark humor.

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        #4
        Originally posted by mbrooke View Post

        Thanks

        But- help my understand why code says its ok:

        1) The gas pipe is technically a grounding electrode as metal gas mains can run the entire town.

        2) A 600amp circuit could energize the fire sprinkler pipping as much as a 200amp circuit.
        The gas pipe should have a di-electric union that prevents the gas pipes from acting like a grounding electrode.
        Cheers and Stay Safe,

        Marky the Sparky

        Comment


          #5
          Originally posted by K8MHZ View Post

          The gas pipe should have a di-electric union that prevents the gas pipes from acting like a grounding electrode.
          What code section?

          But that still does not take care of #2
          Our comedian shamelessly joked about a blackout. Talk about dark humor.

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            #6
            Originally posted by mbrooke View Post

            What code section?
            It's in NFPA13 and I believe somewhere in chapter 10 it specifically prohibits using Fire Sprinklers for GE's

            Originally posted by mbrooke View Post
            But that still does not take care of #2
            See 250.104(B)

            Roger

            Moderator

            Comment


              #7
              Originally posted by mbrooke View Post
              But- help my understand why code says its ok:
              1) The gas pipe is technically a grounding electrode as metal gas mains can run the entire town.
              2) A 600amp circuit could energize the fire sprinkler piping as much as a 200amp circuit.
              Why does the code say that if you run a GEC to structural steel, you size it on the basis of the service conductor size, but if you run one to a ground rod, you need not go bigger than #6 no matter how large the service conductor are? I have no idea.

              Regarding item 1, I can't answer for K8MHZ's comment. It may be a plumbing code, but I don't think it is in the NEC. However, a water pipe can serve as an electrode if it has at least 10 feet in contact with dirt. How long it is after that, even if it runs all through the town, matters not in the least.

              Regarding item 2, if any circuit comes into contact with a piping system that is serving as a grounding electrode, that electrode will utterly disregard the event. By that I mean that dirt will not become part of the fault-clearing path. Rather, the bonding conductors that essentially tie all metal throughout the building, metal that has the possibility of becoming energized, back to the main panel's grounding bus, and from there to the neutral bus via the main bonding jumper, will establish a low-impedance circuit. This will result in a high current that will terminate the event by tripping the main, feeder, or branch circuit breaker, depending on where the fault took place.

              It appears to me that you are confusing the grounding electrode system with the fault clearing duties of the equipment grounding conductors and bonding conductors.


              Charles E. Beck, P.E., Seattle
              Comments based on 2017 NEC unless otherwise noted.

              Comment


                #8
                [QUOTE=charlie b;n2533384]
                Why does the code say that if you run a GEC to structural steel, you size it on the basis of the service conductor size, but if you run one to a ground rod, you need not go bigger than #6 no matter how large the service conductor are? I have no idea.
                A single (or even multiple) ground rod will not have an ultra low resistance even in the best soil, where as structural steal can be the equivalent of 10,000 ground rods in parallel. Also I would think structural steal could in theory become energized by the largest circuit in the building where as a ground rod is not likely.


                Regarding item 1, I can't answer for K8MHZ's comment. It may be a plumbing code, but I don't think it is in the NEC. However, a water pipe can serve as an electrode if it has at least 10 feet in contact with dirt. How long it is after that, even if it runs all through the town, matters not in the least.

                Regarding item 2, if any circuit comes into contact with a piping system that is serving as a grounding electrode, that electrode will utterly disregard the event. By that I mean that dirt will not become part of the fault-clearing path. Rather, the bonding conductors that essentially tie all metal throughout the building, metal that has the possibility of becoming energized, back to the main panel's grounding bus, and from there to the neutral bus via the main bonding jumper, will establish a low-impedance circuit. This will result in a high current that will terminate the event by tripping the main, feeder, or branch circuit breaker, depending on where the fault took place.

                It appears to me that you are confusing the grounding electrode system with the fault clearing duties of the equipment grounding conductors and bonding conductors.
                Of course, which is why you would want the gas, fire, ect bonding conductors sized to 250.122. Do you want a 600amp circuit being cleared via #6?

                It just make no sense to me that structural steel and the water main need 3/0 but not the rest of the piping.
                Our comedian shamelessly joked about a blackout. Talk about dark humor.

                Comment


                  #9
                  Originally posted by roger View Post
                  It's in NFPA13 and I believe somewhere in chapter 10 it specifically prohibits using Fire Sprinklers for GE's

                  [LEFT][COLOR=#000000][FONT=Helvetica] See 250.104(B)

                  Roger

                  As I'm reading it, #6 would be a code violation?


                  (B) Other Metal Piping. If installed in or attached to a building
                  or structure, a metal piping system(s), including gas piping,
                  that is likely to become energized shall be bonded to any of the
                  following:
                  (1) Equipment grounding conductor for the circuit that is
                  likely to energize the piping system
                  (2) Service equipment enclosure
                  (3) Grounded conductor at the service
                  (4) Grounding electrode conductor, if of sufficient size
                  (5) One or more grounding electrodes used, if the grounding
                  electrode conductor or bonding jumper to the
                  grounding electrode is of sufficient size
                  The bonding conductor(s) or jumper(s) shall be sized in
                  accordance with Table 250.122, and equipment grounding
                  conductors shall be sized in accordance with Table 250.122
                  using the rating of the circuit that is likely to energize the
                  piping system(s). The points of attachment of the bonding
                  jumper(s) shall be accessible.
                  Informational Note No. 1: Bonding all piping and metal air
                  ducts within the premises will provide additional safety.
                  Informational Note No. 2: Additional information for gas piping
                  systems can be found in Section 7.13 of NFPA 54 -2015, National
                  Fuel Gas Code.
                  Our comedian shamelessly joked about a blackout. Talk about dark humor.

                  Comment


                    #10
                    Originally posted by mbrooke View Post
                    As I'm reading it, #6 would be a code violation?
                    I think not. Your citation is related to bonding jumpers. The original question, and the sketch, are related to grounding electrode conductors. See my code citation in post #2.


                    Charles E. Beck, P.E., Seattle
                    Comments based on 2017 NEC unless otherwise noted.

                    Comment


                      #11
                      Originally posted by mbrooke View Post


                      As I'm reading it, #6 would be a code violation?


                      (B) Other Metal Piping. If installed in or attached to a building
                      or structure, a metal piping system(s), including gas piping,
                      that is likely to become energized shall be bonded to any of the
                      following:
                      (1) Equipment grounding conductor for the circuit that is
                      likely to energize the piping system
                      .
                      There's no need to go any further than #1, if a 20 amp circuit is the likely culprit that may energize the particular piping a #12 is all that is needed. If a 600 amp circuit is likely to energize it go to Table 250.122 and size it accordingly.

                      Roger
                      Moderator

                      Comment


                        #12
                        I agree with Roger, in that that is how to deal with the bonding jumpers. But I repeat that this thread is not about bonding jumpers. It is about GECs.
                        Charles E. Beck, P.E., Seattle
                        Comments based on 2017 NEC unless otherwise noted.

                        Comment


                          #13
                          Originally posted by charlie b View Post
                          I agree with Roger, in that that is how to deal with the bonding jumpers. But I repeat that this thread is not about bonding jumpers. It is about GECs.
                          The way I read the diagram, the column of items on the right are items to be bonded, not electrodes. The rest of the items are grounding electrode system.

                          Comment


                            #14
                            Originally posted by charlie b View Post
                            I think not. Your citation is related to bonding jumpers. The original question, and the sketch, are related to grounding electrode conductors. See my code citation in post #2.


                            Yes, but to me a gas pipe needs a grounding electrode conductor, not a bonding jumper. I guess the question is what guarantee is there that the gas pipe will have an isolating union.
                            Our comedian shamelessly joked about a blackout. Talk about dark humor.

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                              #15
                              Originally posted by jaggedben View Post

                              The way I read the diagram, the column of items on the right are items to be bonded, not electrodes. The rest of the items are grounding electrode system.
                              Precisely, said very succinctly
                              Our comedian shamelessly joked about a blackout. Talk about dark humor.

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