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Ground wire in MC cable

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    #16
    Originally posted by infinity View Post
    How's this for a guess, the cable was originally designed for pools where an insulated EGC was required and MC was easier to run than a metallic raceway. Of course this has changed.
    Never thought about it that way.

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      #17
      Looking for the history of when and why MC came about, I found this. From the Mike Holt archives, a post by Thomas Horne dated Feb. 25, 2002:

      Originally posted by Thomas Horne
      The restrictions on wiring methods are based on the fire history of that type of occupancy. Since the jacket of type AC cable is the Equipment Grounding Conductor (EGC) if the jacket is damaged the EGC will be broken. In type MC cable any damage that will break the separately insulated EGC is likely to break the other circuit conductors and fault out the circuit. So in places were physical damage to the cable is more likely, such as a commercial garage or movie studio AC is forbidden. In places were large numbers of people are at risk such as movie theaters it is also forbidden.
      So here we have yet another opinion that MC came about because a separate insulated EGC offers a more reliable ground conductor.

      -Hal

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        #18
        Originally posted by hbiss View Post
        Looking for the history of when and why MC came about, I found this. From the Mike Holt archives, a post by Thomas Horne dated Feb. 25, 2002:



        So here we have yet another opinion that MC came about because a separate insulated EGC offers a more reliable ground conductor.

        -Hal
        Could be... but I think that involves a lot of "magical" thinking. Not saying thats how the code thinks/thought, but I personally on my own disagree. However, I thank you none the less for showing me this.

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          #19
          So I'm still looking for how and why MC originated. All you see is that it's an iteration of BX and AC.

          -Hal

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            #20
            JMHO, but the jacket is 'wound' and (i'm told) 5-6 X's the length of interior conductors

            they found this out with the old BX

            if the shell was energized , it wouldn't trip

            but not always because it was made off K&T, because of VD

            we'd see this line of dots, in the old horsehair plaster...and we knew....

            ~RJ~

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              #21
              Originally posted by romex jockey View Post
              JMHO, but the jacket is 'wound' and (i'm told) 5-6 X's the length of interior conductors

              they found this out with the old BX

              if the shell was energized , it wouldn't trip

              but not always because it was made off K&T, because of VD

              we'd see this line of dots, in the old horsehair plaster...and we knew....

              ~RJ~
              That sad part is DIY sites tell HO to take a tester to the box. If it lights, you may now proceed to install 3 prong outlets... just bond to the back of the box.






              Home Center books are the same, creating the idea armor is always an low impedance path:







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                #22
                you forgot HI's MBrooke...~RJ~

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                  #23
                  Originally posted by romex jockey View Post
                  you forgot HI's MBrooke...~RJ~
                  Don't get me started But yes, valid point.

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