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Compact Aluminum Conductor Ampacity Rating

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    Compact Aluminum Conductor Ampacity Rating

    Do compact AL conductors have different allowable ampacities than regular conductors? My understanding was that compact conductors allowed you to put "larger" cables in a smaller conduit, but you still have to go by Table 310.16. I have an electrician who installed conductors that are too small and the inspector is saying that if they are compact, they may be ok. I can't find anything saying that in the NEC.

    #2
    A compact conductor of the same labeled size carries the same current as a standard conductor.

    In other words 250 kcmil standard and a 250 kcmil compact are rated the same. But of course the compact one is smaller diameter.

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      #3
      I was always under the impression that rubber cord used compact conductors. I learned that there is something else out there I have not seen. I have seen some 3/0 copper conductors like thhn that had tiny strands like rubber cord. Not sure what that is called--if anything special at all.
      They say I shot a man named Gray and took his wife to Italy
      She inherited a million bucks and when she died it came to me
      I can't help it if I'm lucky

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        #4
        Originally posted by Dennis Alwon View Post
        I was always under the impression that rubber cord used compact conductors. I learned that there is something else out there I have not seen. I have seen some 3/0 copper conductors like thhn that had tiny strands like rubber cord. Not sure what that is called--if anything special at all.
        Cord probably not. Normal stranding is more flexible that compact stranding. The normal stranding has those spaces in it that allow the strands to slide by each other easier.

        The only place I have seen compact CU is HV cables, it reduces the diameter of the wire and hence the diameter of the insulation.

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          #5
          Compact conductors are a design of the aluminum industry. The use of compact strand aluminum conductors will often let you install the same size raceway as you would use for standard copper conductors of the same ampacity. If you don't have to increase the raceway size for the same circuit ampacity, it increases the economic advantage of aluminum conductors.

          That being said, you can get copper compact strand conductors, but they are not as common as aluminum.
          Don, Illinois
          (All code citations are 2017 unless otherwise noted)

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            #6
            Originally posted by Dennis Alwon View Post
            I was always under the impression that rubber cord used compact conductors. I learned that there is something else out there I have not seen. I have seen some 3/0 copper conductors like thhn that had tiny strands like rubber cord. Not sure what that is called--if anything special at all.
            That would probably be Type W power cable or DLO cable. In general the OD of a fine strand conductor is larger than than of a standard strand conductor.
            Don, Illinois
            (All code citations are 2017 unless otherwise noted)

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              #7
              Originally posted by don_resqcapt19 View Post
              That would probably be Type W power cable or DLO cable. In general the OD of a fine strand conductor is larger than than of a standard strand conductor.

              Thanks Don--I never checked the insulation but I saw these conductors a year or two ago in a Cutler Hammer 400 amp meter main panel. I started a thread and I believe I called them compact conductors incorrectly. They had one set of 3/0 copper fine strand conductor cable feeding the 400 amp panel. UL listed and when called CH said they got a number of calls but they stood behind there product and said they tested it and it works.
              They say I shot a man named Gray and took his wife to Italy
              She inherited a million bucks and when she died it came to me
              I can't help it if I'm lucky

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                #8
                Dennis, If the fine strand conductor was in a manufactured product it may have been welding cable. I have seen listed manufactured products that used welding cable for the wiring.
                Don, Illinois
                (All code citations are 2017 unless otherwise noted)

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                  #9
                  Originally posted by don_resqcapt19 View Post
                  Dennis, If the fine strand conductor was in a manufactured product it may have been welding cable. I have seen listed manufactured products that used welding cable for the wiring.

                  That makes sense. Just can't understand how 3/0 works for 400 amps.
                  They say I shot a man named Gray and took his wife to Italy
                  She inherited a million bucks and when she died it came to me
                  I can't help it if I'm lucky

                  Comment


                    #10
                    Originally posted by Dennis Alwon View Post
                    That makes sense. Just can't understand how 3/0 works for 400 amps.
                    Don, Illinois
                    (All code citations are 2017 unless otherwise noted)

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