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    #16
    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.
    What code section says that?
    Don, Illinois
    (All code citations are 2017 unless otherwise noted)

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      #17
      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'm pretty certain flexible conduits are not permitted to be used as an EGC on a 1200 amp circuit, but I may be off just a little here.
      I live for today, I'm just a day behind.

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        #18
        Originally posted by don_resqcapt19 View Post
        What code section says that?


        NEC does not allow 6' or longer flexible metal conduit to serve as EGC unless a proper ground conductor is added. This means in this case the code allows the raceway does not need to be compliant with the current capacity for fault clearing requirement

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          #19
          Originally posted by Brian Dang View Post
          NEC does not allow 6' or longer flexible metal conduit to serve as EGC unless a proper ground conductor is added. This means in this case the code allows the raceway does not need to be compliant with the current capacity for fault clearing requirement
          Not exactly, because in that case a bonding jumper is required for the flexible conduit.
          Don, Illinois
          (All code citations are 2017 unless otherwise noted)

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            #20
            Originally posted by don_resqcapt19 View Post
            Not exactly, because in that case a bonding jumper is required for the flexible conduit.
            Don,

            I'm not quite sure I understand this. I thought the flexible conduit was already bonded to the boxes using listed connectors. How exactly you do this?

            Regards,
            Brian

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              #21
              The bonding jumper would be a wire from one end of the flex to the other, either inside or outside the flex (as long as not subject to damage.)

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                #22
                Originally posted by GoldDigger View Post
                The bonding jumper would be a wire from one end of the flex to the other, either inside or outside the flex (as long as not subject to damage.)
                Is this bonding jumper in addition to the EGC which was required for fault clearing (when using long flex conduit), or they are the same thing? If they are two different conductors, then can I bond the single EGC to every box on this branch to meet the code without adding the said bonding jumper?

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                  #23
                  There is some small difference, in that an EGC would only have to pass through instead of being bonded at each end of the flex. If you bonded the EGC at each end of the flex (an allowed option, AFAIK) it would also serve as the (not necessarily required) bonding jumper.
                  Last edited by GoldDigger; 04-29-16, 05:14 PM.

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                    #24
                    There must be a bond around the flex, the flex can not be the sole EGC other then a few circumstances up to 6 feet length, and up to 20 amps overcurrent devices - liquidtight metal flex does allow up to 60 amps overcurrent device for 3/4 to 1-1/4 size though. If the flex is used for prevention of transferring vibration it typically isn't allowed to be used as an EGC either.
                    I live for today, I'm just a day behind.

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                      #25
                      I got it. Thanks.

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