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250.64(C) GEC irreversible splices - why?

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    250.64(C) GEC irreversible splices - why?

    Code:
    250.64(C) "GEC's shall be installed in one continuous length without a splice or joint except as permitted in (1) and (2)
      (1) Splicing shall be permitted only by irreversible compression-type  connectors listed as grounding and bonding equipment or by the  exothermic welding process.
    What's the reasoning behind the irreversible connectors requirement for the GEC? Is it to prevent tempering or to ensure proper surge current passage? Would a split bolt, acorn, or screw lug style connector work the same from a physics perspective? thanks

    #2
    Originally posted by EBQ View Post
    Code:
    250.64(C) "GEC's shall be installed in one continuous length without a splice or joint except as permitted in (1) and (2)
      (1) Splicing shall be permitted only by irreversible compression-type  connectors listed as grounding and bonding equipment or by the  exothermic welding process.
    What's the reasoning behind the irreversible connectors requirement for the GEC? Is it to prevent tempering or to ensure proper surge current passage? Would a split bolt, acorn, or screw lug style connector work the same from a physics perspective? thanks
    Any connector properly installed will perform it's purpose from a physics perspective however, an irreversible connection is supposed to be just that which is permanent.

    Roger
    Moderator

    Comment


      #3
      Originally posted by EBQ View Post
      Code:
      250.64(C) "GEC's shall be installed in one continuous length without a splice or joint except as permitted in (1) and (2)
        (1) Splicing shall be permitted only by irreversible compression-type  connectors listed as grounding and bonding equipment or by the  exothermic welding process.
      What's the reasoning behind the irreversible connectors requirement for the GEC? Is it to prevent tempering or to ensure proper surge current passage? Would a split bolt, acorn, or screw lug style connector work the same from a physics perspective? thanks
      There is no reason. It's just one part of the continued over emphasis in the importance of grounding
      Ethan Brush - East West Electric. NY, WA. MA

      "You can't generalize"

      Comment


        #4
        Originally posted by electrofelon View Post
        There is no reason. It's just one part of the continued over emphasis in the importance of grounding
        Which may not be as important as some want to think it is. Bonding is definitely important though.
        I live for today, I'm just a day behind.

        Comment


          #5
          Because for some unknown reason CMP 5 seems to think that a GEC is more important than an EGC. It is my opinion that the EGC is far more important than the GEC.
          Don, Illinois
          (All code citations are 2017 unless otherwise noted)

          Comment


            #6
            Originally posted by don_resqcapt19 View Post
            Because for some unknown reason CMP 5 seems to think that a GEC is more important than an EGC. It is my opinion that the EGC is far more important than the GEC.
            I agree, the system would work just fine with no electrodes or GEC's as long as the main bonding jumper was in place.
            Rob

            Moderator

            All responses based on the 2017 NEC unless otherwise noted

            Comment


              #7
              Does the GES even do anything meaningful locally for surge currents? when service neutral already provides a lower resistance path to absorb excess voltage and is bonded to earth at the transformer.

              Other than bonding earth to metal to equalize potentials, what else does a GES accomplish?

              Comment


                #8
                Originally posted by EBQ View Post
                Does the GES even do anything meaningful locally for surge currents? when service neutral already provides a lower resistance path to absorb excess voltage and is bonded to earth at the transformer.

                Other than bonding earth to metal to equalize potentials, what else does a GES accomplish?
                It just adds one more electrode to a large network of electrodes.
                I live for today, I'm just a day behind.

                Comment


                  #9
                  Originally posted by kwired View Post
                  It just adds one more electrode to a large network of electrodes.
                  So it's really insurance for the whole, rather than the individual, at least as it relates to a surge.

                  Comment


                    #10
                    Originally posted by EBQ View Post
                    So it's really insurance for the whole, rather than the individual, at least as it relates to a surge.
                    mostly yes.

                    Now inspectors seem to be trained to think a missing GEC is the worst possible thing that can happen, and occupants of a building without one are certain to die because of it, reality is it is not.
                    I live for today, I'm just a day behind.

                    Comment


                      #11
                      Originally posted by EBQ View Post
                      So it's really insurance for the whole, rather than the individual, at least as it relates to a surge.
                      I don't even think it does that. It references one point in the electrical system to earth and 0 V intentionally and if that doesn't happen you end up with a rats nest of unintentional "faults" over your building, neighborhood, county and so on.
                      If Billy Idol is on your playlist go reevaluate your life.

                      Comment


                        #12
                        Originally posted by ActionDave View Post
                        I don't even think it does that. It references one point in the electrical system to earth and 0 V intentionally and if that doesn't happen you end up with a rats nest of unintentional "faults" over your building, neighborhood, county and so on.
                        The potential on your secondary circuit is only between your service disconnect and the source, and any secondary distribution pedestals or similar that may also have an electrode. But yes the voltage drop on primary neutral still presents some voltage to earth on your grounded service conductor, and some primary current can flow through your service neutral, and through any ground path it may find on your premises, whether you have a GES or not.
                        I live for today, I'm just a day behind.

                        Comment


                          #13
                          Originally posted by ActionDave View Post
                          I don't even think it does that. It references one point in the electrical system to earth and 0 V intentionally and if that doesn't happen you end up with a rats nest of unintentional "faults" over your building, neighborhood, county and so on.
                          The connection to an electrode doesn't make the voltage on the service grounded conductor, as measured to earth, zero. It just raises the voltage for a small area of the earth around the electrode to the voltage on the service grounded conductor.
                          Don, Illinois
                          (All code citations are 2017 unless otherwise noted)

                          Comment


                            #14
                            The origin of the wording in 250.64(C) is old.

                            It predates nonmetallic piping systems and supplemental grounding electrodes.

                            It predates most rural electrification.

                            It is my opinion that the language reflected the (then) most common installation of a GEC being only a conductor going to a metallic water pipe system supplied by a metallic municipal water system. In the event of a loss of continuity in the grounded service conductor, the water piping-to-neighbors premises wiring system would mitigate voltage swings under load.

                            Maybe its time to relax this "irreversible connection" requirement given the increasing prevalence of nonmetallic systems in new construction?
                            Another Al in Minnesota

                            Comment


                              #15
                              Originally posted by kwired View Post
                              The potential on your secondary circuit is only between your service disconnect and the source, and any secondary distribution pedestals or similar that may also have an electrode. But yes the voltage drop on primary neutral still presents some voltage to earth on your grounded service conductor, and some primary current can flow through your service neutral, and through any ground path it may find on your premises, whether you have a GES or not.
                              Originally posted by don_resqcapt19 View Post
                              The connection to an electrode doesn't make the voltage on the service grounded conductor, as measured to earth, zero. It just raises the voltage for a small area of the earth around the electrode to the voltage on the service grounded conductor.
                              I understand all that. The point I was wanting to make is that it's easier to intentionally ground your electrical system than it is to let time and nature take its course or to try and keep it isolated.
                              If Billy Idol is on your playlist go reevaluate your life.

                              Comment

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