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    Transitioning couplings

    Hi guys,

    What kind of couplings do you use when transitioning from GRC above grade to PVC below grade?

    Thanks,
    EE

    #2
    Steel coupling and PVC male adapter or just a PVC female adapter. The former is probably stronger.
    Master Electrician
    Electrical Contractor
    Richmond, VA

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      #3
      Originally posted by LarryFine View Post
      Steel coupling and PVC male adapter or just a PVC female adapter. The former is probably stronger.
      I would try to never use a TA underground, too weak. FA is much stronger.

      Comment


        #4
        Originally posted by oldsparky52 View Post

        I would try to never use a TA underground, too weak. FA is much stronger.
        Interesting. I figured that an external fitting is more likely to split from being stressed than an internal fitting.
        Master Electrician
        Electrical Contractor
        Richmond, VA

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          #5
          I much prefer the female thread to be the steel one. It's the one most likely to split.

          Comment


            #6
            Take advice from the plumbers on this one. On a metal to plastic connection, always plastic male to metal female.

            Sent from my RCT6A03W13E using Tapatalk

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              #7
              Originally posted by rjniles View Post
              Take advice from the plumbers on this one. On a metal to plastic connection, always plastic male to metal female.

              Sent from my RCT6A03W13E using Tapatalk
              But they deal with the pipe/fitting needing to contain pressure, we don't. Other stress factors are what comes to play. That said if the transition is below grade, those stresses probably are somewhat minimal other than possibly frost heave or settling if you didn't account for them when you installed it.
              I live for today, I'm just a day behind.

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                #8
                And there is the age old technical issue of the MA only being listed to be used with a locknut. Petty, but real.

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                  #9
                  Originally posted by texie View Post
                  And there is the age old technical issue of the MA only being listed to be used with a locknut. Petty, but real.
                  Do you have a source for this?

                  They don't even come with a locknut when you buy it. And many go into a hub. Yes, I do realize not to expect listings to be accurate or make sense, but I'd still like to verify this one.

                  Comment


                    #10
                    Originally posted by MAC702 View Post

                    Do you have a source for this?

                    They don't even come with a locknut when you buy it. And many go into a hub. Yes, I do realize not to expect listings to be accurate or make sense, but I'd still like to verify this one.
                    This from carlon doesnt say locknuts only for TA's:

                    https://carlonsales.com/techinfo/bro..._40_and_80.pdf

                    For adapting nonmetallic conduits to boxes, threaded fittings, metallic systems. Male threads on one end, socket end on other
                    Im not saying that is the last word, maybe there is something in the listing documents or product standards?
                    Ethan Brush - East West Electric. NY, WA. MA

                    "You can't generalize"

                    Comment


                      #11


                      MA's are much more failure prone in my opinion, the plastic is thinner at the thread connection on an MA than on an FA. We can't have a connection fail for the sake of $1.00 part.

                      Comment


                        #12
                        Originally posted by electrofelon View Post

                        This from carlon doesnt say locknuts only for TA's:

                        https://carlonsales.com/techinfo/bro..._40_and_80.pdf



                        Im not saying that is the last word, maybe there is something in the listing documents or product standards?
                        You may be correct per that Carlon page. I would normally look this up on UL Product Spec but it has been retired. It is now called product IQ and needs a login which I have but have not yet looked it over enough to be proficient using it yet. It is a lot different than it used to be.
                        I made my comment based on the past fact that conduit connectors (such as am EMT connector) were only listed for use with locknuts. That may not be the case for a PVC MA.

                        Comment


                          #13
                          As a plumber by trade.....and assuming you are running schedule 80 PVC conduit.....I'd suggest a 6" threaded PVC nipple, cut it in half, and glued on with a coupling. I can't comment on the "code compliance" of it. They also make FA's with a metal band around the threaded side but they are a lot more money.

                          Comment


                            #14
                            Originally posted by Cow View Post

                            MA's are much more failure prone in my opinion, the plastic is thinner at the thread connection on an MA than on an FA. We can't have a connection fail for the sake of $1.00 part.
                            How is the MA likely to fail? I've split FA's before I learned to be careful when I use them. I can't even think of a way to make an MA fail.

                            Comment


                              #15
                              Originally posted by texie View Post
                              ...I made my comment based on the past fact that conduit connectors (such as am EMT connector) were only listed for use with locknuts. That may not be the case for a PVC MA.
                              Indeed, this would technically preclude PVC FAs when the metallic raceway is going to be EMT? Something I've seen, done, etc, etc. In fact, this is the method I learned as an apprentice from all the old hands.

                              EMT connectors typically have looser threads than threaded GRC (like in the OP), so wouldn't be nearly as big a splitting issue for FAs, either.

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