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Thread: 250.64(C) GEC irreversible splices - why?

  1. #11
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    Quote 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 you don't think too good, don't think too much.

  2. #12
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    Quote 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.

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    Quote 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)

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    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

  5. #15
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    Quote 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.
    Quote 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 you don't think too good, don't think too much.

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    Quote 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
    The reason is because of Larry, the Cable Guy. He would always loosen the burndy to insert his ground wire and wasn't talented enough to tighten it back up. So the rule was changed to irreversible and that ended the problem.

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    Quote Originally Posted by ActionDave View Post
    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.
    That I can agree with, but for services, if incoming is already a grounded system, does it really matter if you ground it one more time?
    I live for today, I'm just a day behind.

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    Quote Originally Posted by kwired View Post
    That I can agree with, but for services, if incoming is already a grounded system, does it really matter if you ground it one more time?
    No, it doesn't, but I think we're outnumbered by those that think it does.
    If you don't think too good, don't think too much.

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    The reason is because of Larry, the Cable Guy. He would always loosen the burndy to insert his ground wire and wasn't talented enough to tighten it back up. So the rule was changed to irreversible and that ended the problem.
    But Larry would loosen the GEC to GE connector to insert his ground wire all the same

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