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250.118 - using emt conduit as a ground

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    #31
    Originally posted by petersonra View Post
    It seems to me that if the EMT is rusting out it is not suitable to use it at all in that location.
    If rusting from inside out was not arranged to drain.
    I live for today, I'm just a day behind.

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      #32
      Originally posted by petersonra View Post
      It seems to me that if the EMT is rusting out it is not suitable to use it at all in that location.
      Used to be it was used in concrete... now pvc conduit more common. But, emt is still allowed in concrete as I recall.
      Student of electrical codes. Please Take others advice first.

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        #33
        Originally posted by Adamjamma View Post
        Used to be it was used in concrete... now pvc conduit more common. But, emt is still allowed in concrete as I recall.
        PVC preferred in slab on grade or in walls below grade. Above grade I don't think matters much most cases unless corrosive agents are involved in the general area.
        I live for today, I'm just a day behind.

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          #34
          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?
          In rooftop applications it is specified to overcome the possibility; some would say likelihood; that the connections of the steel EMT will corrode open.
          Tom Horne

          "This alternating current stuff is just a fad. It is much too dangerous for general use." Thomas Alva Edison

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            #35
            Originally posted by kec View Post
            Agree, if set screws are tight then your are good to go, but Ive come across installations [done by others] with duck tape used for couplings.
            Are you having us on? I've seen a lot of duct tape used to render fittings concrete tight.
            Tom Horne

            "This alternating current stuff is just a fad. It is much too dangerous for general use." Thomas Alva Edison

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              #36
              Originally posted by hornetd View Post
              In rooftop applications it is specified to overcome the possibility; some would say likelihood; that the connections of the steel EMT will corrode open.
              Why would someone specify the need for a grounding conductor..... when they could specify a raceway fitting that won't corrode away?

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                #37
                Project manager! Need I say more?

                Originally posted by 480sparky View Post
                Why would someone specify the need for a grounding conductor..... when they could specify a raceway fitting that won't corrode away?
                Because it's cheaper. Why Else? They specify compression couplings but many of those are not evan listed as rain-tight. And then for good measure they specify aluminum boxes to throw dissimilar metals into the mix. I've actually have seen one aluminum EMT job with all compatible fittings and boxes but that was on the roof of a a Biotechnology Laboratory.

                But why am I complaining about this stuff when I have had an inspector say he preferred plastic boxes for their additional inside volume used with EMT in a Fire Alarm System. Before you ask they were not the ones with the bonding strap inside the box to bond all of the KOs to each other. That same inspector approved a Fire Pump Controller with no neutral conductor back to the Wye connected utility transformer. But I was just an Electrician on that job and the project manager thought that the foreman was a hero for all of the money he saved.
                Tom Horne

                "This alternating current stuff is just a fad. It is much too dangerous for general use." Thomas Alva Edison

                Comment


                  #38
                  Originally posted by hornetd View Post
                  In rooftop applications it is specified to overcome the possibility; some would say likelihood; that the connections of the steel EMT will corrode open.
                  Design decision, not a code requirement. Just as much design decision as one could run stainless or brass conduit and probably have little or no corrosion troubles, but would definitely be more expensive.
                  I live for today, I'm just a day behind.

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                    #39
                    Originally posted by hornetd View Post
                    Are you having us on? I've seen a lot of duct tape used to render fittings concrete tight.
                    No, I get using tape to facilitate helping vacuum or making fittings tight and have used this method but what I was saying is I came across duck tape used as the coupling only

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                      #40
                      Originally posted by peter d View Post
                      Pfft, not only do I run a ground on the inside, I run one on the outside as well.
                      Oh yeah... I do that plus throw a little dirt in to the box.

                      Comment


                        #41
                        Well, I will admit that I prefer a grounding conductor in EMT. I very rarely see a job that has ANY engineer's input that doesn't require a ground, and if I were an inspector, I would obviously not require ground, but I would make it more difficult for the installer by always insisting on spot checking the tightness of connectors and couplings during rough in inspections. this would include making sure a lift was available for coupling way up high. These are the ones I see as most often left loose. Find one, fail the job. While I consider myself a conscientious worker, I know that I have accidentally left couplings loose, or only tightened a compression fitting with one wrench. I understand the arguments in the other direction and I am not implying that those who take the no ground position are wrong just that I believe installations are better off with a separated grounding wire.


                        I know what I don't know, and I know where to go to find it!

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                          #42
                          Originally posted by hornetd View Post
                          Because it's cheaper. .....
                          Since when did EE's care about cost?

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                            #43
                            Originally posted by 480sparky View Post
                            Since when did EE's care about cost?
                            definitely since never, in my experience.


                            I know what I don't know, and I know where to go to find it!

                            Comment


                              #44
                              Originally posted by Strathead View Post
                              Well, I will admit that I prefer a grounding conductor in EMT. I very rarely see a job that has ANY engineer's input that doesn't require a ground, and if I were an inspector, I would obviously not require ground, but I would make it more difficult for the installer by always insisting on spot checking the tightness of connectors and couplings during rough in inspections. this would include making sure a lift was available for coupling way up high. These are the ones I see as most often left loose. Find one, fail the job. While I consider myself a conscientious worker, I know that I have accidentally left couplings loose, or only tightened a compression fitting with one wrench. I understand the arguments in the other direction and I am not implying that those who take the no ground position are wrong just that I believe installations are better off with a separated grounding wire.
                              I might be ok with that, but if I didn't use a lift at install, I am not providing you with one. Say I crawled through rafters or was harnessed and supported by rope/cable when I installed it, I will hand you the harness and say "have at it"
                              I live for today, I'm just a day behind.

                              Comment


                                #45
                                Originally posted by kwired View Post
                                I might be ok with that, but if I didn't use a lift at install, I am not providing you with one. Say I crawled through rafters or was harnessed and supported by rope/cable when I installed it, I will hand you the harness and say "have at it"
                                I agree, but in the scope of long term work in a jurisdiction it would end up being the path of least resistance to just put a ground in. I have rolled over to an inspector on things a lot more heinous than this just because it was going to be the best bet in the long run.


                                I know what I don't know, and I know where to go to find it!

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