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OT? Is There More Than One Thread Used On 1/2" Conduit?

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  • OT? Is There More Than One Thread Used On 1/2" Conduit?

    I purchased a LED flood lamp for my back yard and it has a mounting that I thought had 1/2" conduit threads. It is going to go on an outdoor fixture that has three lamps on it to send light all around the back yard. It will be in the center. The three mounting holes on the cover are about 1 1/2" to 2" apart and I believe they are threaded with standard, conduit threads. The new flood light's mount does not allow it to stick out very far. Since it will be between two existing flood lights in the more or less standard round, cone shaped cowlings, I was going to add a conduit offset elbow plus a coupling.

    https://www.mcmaster.com/conduit-fit...~offset-elbow/

    But when I checked the threads on the LED flood light, they did not mate with standard, 1/2" conduit threads. They are just a bit smaller in diameter and finer in pitch. Is this some kind of European or oriental conduit thread, or what? And can I get conduit fittings with this thread? What do I ask for?

    I am going to try to measure the threads tomorrow.
    Paul A.
    SE Texas

    And if you look REAL close at an analog signal,
    You will find that it has discrete steps.

  • #2
    Paul,

    They are most likely ISO pipe threads (which are British Standard Pipe threads re-named).

    https://www.womackmachine.com/engine...-thread-sizes/

    George B.

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    • #3
      Deleted.
      Last edited by Arcane; 11-22-2020, 07:11 PM.
      Location: Saskatoon, Saskatchewan, Canada

      Comment


      • #4
        Drill the threads out to 7/8" and use a conduit nut on the inside of the fixture box.

        -D
        DZER

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        • #5
          A good deal of the Chinese origin lamps have 16mm stubs. "looks like npt"; NOT!

          Comment


          • #6
            Most all of the electrical apparatus made in china seems to be out of spec as to one dimension or the other, especially threads. If you have a 1/2" NPT tap just chase the hole. (yes I know electrical conduit thread is straight thread...)

            Comment


            • #7
              The common conduit used in the UK is thin walled tube and has to have dedicated conduit threads in it. This thread is fine pitched, if something like a pipe thread was tried, it would end badly as the depth of the pipe thread exceeds the wall thickness of the conduit tubing.

              Comment


              • #8
                Originally posted by old mart View Post
                The common conduit used in the UK is thin walled tube and has to have dedicated conduit threads in it. This thread is fine pitched, if something like a pipe thread was tried, it would end badly as the depth of the pipe thread exceeds the wall thickness of the conduit tubing.
                Thinwall in the US is "electrical metallic tubing", and is NEVER threaded. One ALWAYS uses a fitting on the end.
                CNC machines only go through the motions

                Comment


                • #9
                  N.A. electrical standard for thread is NPSM, National Pipe Straight Mechanical.
                  https://www.thebalancesmb.com/seven-...onduits-844832

                  I like to use Sealed metallic flexible conduit, especially if lots of bends.
                  Max.

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                  • #10
                    PANZERGEWINDE

                    Is it Panzergewinde threads AKA PG? German standard that is used on industrial automation stuff quite a bit. You'll see it on stuff from asia sometimes. Mcmaster sells taps and some random parts in PG thread.

                    Nomenclature is PG-#, # being the size. refs https://www.yamawa.com/Portals/0/res...f/tips-068.pdf https://en.wikipedia.org/wiki/Panzergewinde

                    Other guess would be rando fine thread metric with a face seal washer/oring?
                    -paul

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                    • #11
                      Any chance you can run a 1/2" pipe tap partially through the existing hole to allow for a snug pipe thread fit??

                      JL....

                      ​​​​​

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                      • #12
                        Sorry, but that won't work. The new light has what appears to be a permanently attached mount with EXTERNAL threads and a matching nut. I want to extend that and standard US conduit stuff does not fit. It is close, but no cigar.



                        Originally posted by Doozer View Post
                        Drill the threads out to 7/8" and use a conduit nut on the inside of the fixture box.

                        -D
                        Paul A.
                        SE Texas

                        And if you look REAL close at an analog signal,
                        You will find that it has discrete steps.

                        Comment


                        • #13
                          With so many possibilities, I may have to just drill or ream out the female threads on a US fitting and then use JB Weld to join the two. I just thought I would ask first.
                          Paul A.
                          SE Texas

                          And if you look REAL close at an analog signal,
                          You will find that it has discrete steps.

                          Comment


                          • #14
                            M12x1.5 is a standard cable gland thread.

                            Comment


                            • #15
                              I suspect you can welcome the new Chinese Stuff Version II, the "we ain't making this your way any more, take it our way or leave it" version. Likely the threads etc are a chinese standard type.

                              Why not make an adapter for it? You have a shop, and from what you say, you do not even need the threads, it has a nut already.
                              CNC machines only go through the motions

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