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250.118 - using emt conduit as a ground

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    250.118 - using emt conduit as a ground

    Looks like it's okay in 250.118 to use emt as a ground. Is it also code to run subpanel feeder circuit without a equipment grounding conductor as long as the wires are within emt pipe the whole way?

    #2
    Yes; why would think it wouldn't be?

    Roger
    Moderator

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      #3
      To add to Roger's response, many studies have shown that a metallic raceway performs better at clearing a fault than a wire type equipment grounding conductor.

      Comment


        #4
        We use EMT as an EGC all of the time unless someone is paying for a wire type EGC in the raceway.
        Rob

        Moderator

        All responses based on the 2017 NEC unless otherwise noted

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          #5
          Originally posted by infinity View Post
          We use EMT as an EGC all of the time unless someone is paying for a wire type EGC in the raceway.


          I don't get the obsession with wire EGC's. I always encounter EMT installations done from the 1960's to the 1980's and it never had a separate ground wire. Now it does.

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            #6
            emt as ground

            just seems weird, but ok. thanks

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              #7
              emt as ground

              I have probably spent too many years as a romex jockey.

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                #8
                Originally posted by difowler1 View Post
                just seems weird, but ok. thanks
                Not weird at all. The size of EMT large enough for a given set of conductors has a lower impedance than the associated EGC size would.
                Master Electrician
                Electrical Contractor
                Richmond, VA

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                  #9
                  Originally posted by difowler1 View Post
                  just seems weird, but ok. thanks
                  It did to me, too, because all my apprenticeship years were for places that spec'd the wire EGC, so it was normal for me. Now, people pay me to just make it work, and I'm the one buying and pulling the wire, so....

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                    #10
                    Originally posted by peter d View Post


                    I don't get the obsession with wire EGC's. I always encounter EMT installations done from the 1960's to the 1980's and it never had a separate ground wire. Now it does.
                    Seen many from the time period you mentioned with poorly supported raceway contributing to broken fittings resulting in loss of EGC, also seen loose set screws or compression nuts, but that is all workmanship issues more than anything IMO. Have seen poorly made up EGC's in cable wiring methods as well - open continuity is still open continuity.

                    I do a lot of grain storage bins and handling equipment. Generally all steel structures and equipment. I do run EGC's in flexible conduits or in any non metallic raceways (which is usually just underground raceways in these applications) but see running any wire EGC in most of said systems as pointless, the equipment/structures are very effective fault return path, and usually more effective than my raceways, so if a fitting didn't get tightened it doesn't really matter much from equipment grounding perspective.
                    I live for today, I'm just a day behind.

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                      #11
                      Pulling a wire type EGC is more about a backup or assured bonding.

                      Much like a safety chain installed on a perfectly supported pendant fixture.

                      JAP>

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                        #12
                        Plus, dropping that one conductor when emt is used, helps somewhat for the added conductors we now have to add for MWBC's that we didn't used to have to install.

                        That is for us old dogs that always used MWBC's and now don't like tying individual circuit handles together.

                        JAP>

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                          #13
                          Originally posted by jap View Post
                          Pulling a wire type EGC is more about a backup or assured bonding.

                          Much like a safety chain installed on a perfectly supported pendant fixture.

                          JAP>
                          Which NEC only requires additional paths for certain art 517 applications (could be other specific sections but am not aware of any), outside of that it is a design decision.
                          I live for today, I'm just a day behind.

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                            #14
                            Originally posted by kwired View Post
                            Which NEC only requires additional paths for certain art 517 applications (could be other specific sections but am not aware of any), outside of that it is a design decision.
                            If the raceway is so good as an EGC why is there ever a need for redundant grounding? Needs to be extra good?
                            Rob

                            Moderator

                            All responses based on the 2017 NEC unless otherwise noted

                            Comment


                              #15
                              Originally posted by infinity View Post
                              If the raceway is so good as an EGC why is there ever a need for redundant grounding? Needs to be extra good?
                              I didn't write the rule, apparently it knows when it is in a health care facility and gets nervous or something
                              I live for today, I'm just a day behind.

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