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    Equipment Grounding

    I work for a Utility and we hooked up a 1200 amp service today. From the 1200 amp disconnect they ran a #6 equipment ground to the main sub panel. The inspector allowed this because the #6 wasn't needed as it was run in EMT. Another install involved a feeder tap from a 400 amp bus to a 200 amp disconnect. The equipment ground was a #6 that was too small for this install. The inspector said it ok because it run in EMT conduit. Is there anywhere in the code that states if a redundant ground is run, it must be appropriate size? Thanks in advance.

    #2
    AFIK, IF a conductor type equipment ground is installed in a raceway which qualifies as an equipment ground, the conductor must still be sized by the appropriate Table (250.122)
    At my age, I'm accustomed to restaurants asking me to pay in advance, but now my bank has started sending me their calendar one month at a time.

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      #3
      Originally posted by augie47 View Post
      AFIK, IF a conductor type equipment ground is installed in a raceway which qualifies as an equipment ground, the conductor must still be sized by the appropriate Table (250.122)
      Thank you. Just what I thought. Some inspectors don't like to be proven wrong. Any advise on how to handle inspectors with an attitude that don't care to hear that they are mistaken??

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        #4
        Show him the section of the Code, not to prove him wrong, but ask him for clarification or explanation for your benefit ?

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          #5
          Originally posted by Brian Dang View Post
          Show him the section of the Code, not to prove him wrong, but ask him for clarification or explanation for your benefit ?
          At my age, I'm accustomed to restaurants asking me to pay in advance, but now my bank has started sending me their calendar one month at a time.

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            #6
            If the installer disconnects the 6 awg ground wire and tapes its ends he would be now code compliant.

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              #7
              Originally posted by darekelec View Post
              If the installer disconnects the 6 awg ground wire and tapes its ends he would be now code compliant.
              Thanks thats a good idea

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                #8
                There are a number of code users that say the same as the inspector in this case. I don't think the code clearly addresses the issue and I can see good arguments for either side.
                Don, Illinois
                (All code citations are 2017 unless otherwise noted)

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                  #9
                  Originally posted by newt View Post
                  Thanks thats a good idea
                  Yes, it makes it code compliant, but the impedance of the fault clearing path will be greater than it was with the non-compliant installation.
                  Don, Illinois
                  (All code citations are 2017 unless otherwise noted)

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                    #10
                    Originally posted by Brian Dang View Post
                    Show him the section of the Code, not to prove him wrong, but ask him for clarification or explanation for your benefit ?
                    Originally posted by augie47 View Post
                    [COLOR="blue"]"Electricity is really just organized lightning." George Carlin


                    Derek[/COLOR]

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                      #11
                      Originally posted by don_resqcapt19 View Post
                      Yes, it makes it code compliant, but the impedance of the fault clearing path will be greater than it was with the non-compliant installation.
                      The reason it probably isn't compliant in the original situation is that the incorrect EGC cannot carry the fault current on its own. I would imagine that the intent of the rule is to have all possible EGC paths be independently compliant, and therefore not depending on any parallel EGC path.


                      Current doesn't just take the "path of least resistance". It takes all paths, of all resistances, inversely proportional to the resistance of each path.

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                        #12
                        Originally posted by Carultch View Post
                        The reason it probably isn't compliant in the original situation is that the incorrect EGC cannot carry the fault current on its own. I would imagine that the intent of the rule is to have all possible EGC paths be independently compliant, and therefore not depending on any parallel EGC path.


                        Current doesn't just take the "path of least resistance". It takes all paths, of all resistances, inversely proportional to the resistance of each path.
                        I am not convinced that it is not compliant, but even if it is, disconnecting the EGC of the wire type, even where it is smaller than required by T 250.122, increases the impedance of the fault return path.

                        We are not "depending" in a parallel path here...the raceway is a compliant fault clearing path. There is a possibly non-compliant path connected in parallel. If the system is safe when you disconnect and tape up the EGC of the wire type, it is still safe if that conductor remains connected.
                        Don, Illinois
                        (All code citations are 2017 unless otherwise noted)

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                          #13
                          Originally posted by augie47 View Post
                          AFIK, IF a conductor type equipment ground is installed in a raceway which qualifies as an equipment ground, the conductor must still be sized by the appropriate Table (250.122)
                          The reason this installation should not be code compliant, even thought the total grounding path impedance is smaller than the EMT itself, is that with the GEC installed in the raceway, the raceway does not need to be compliant with the current capacity for fault clearing requirement. E.g. once GEC had been installed EMT can be substituted by flex metal conduit down stream, which by itself cannot be longer than 6 ft without GEC.

                          Comment


                            #14
                            Originally posted by Brian Dang View Post
                            The reason this installation should not be code compliant, even thought the total grounding path impedance is smaller than the EMT itself, is that with the GEC installed in the raceway, the raceway does not need to be compliant with the current capacity for fault clearing requirement. E.g. once GEC had been installed EMT can be substituted by flex metal conduit down stream, which by itself cannot be longer than 6 ft without GEC.
                            This thread is not about a GEC.

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                              #15
                              Sorry, I meant EGC and not GEC

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