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    Knob and Tube wiring

    Knob and Tube wiring

    New postby bigdog on Tue Nov 10, 2015 3:39 pm

    Jerry

    Would you agree with this statement:
    Only a short circuit (hot touching neutral) would cause a fuse to melt or trip a breaker with knob and tube wiring. With no ground wire a ground fault would not melt a fuse or tip a breaker.

    Alright I'm bored and this just went through my mind....whats left of it.

    David
    bigdog
     
    Posts: 47
    Joined: Thu Apr 12, 2012 10:54 pm

    Re: Knob and Tube wiring

    New postby Jerry Peck - Codeman on Tue Nov 10, 2015 4:20 pm

    David,

    bigdog wrote:Would you agree with this statement:
    Only a short circuit (hot touching neutral) would cause a fuse to melt or trip a breaker with knob and tube wiring. With no ground wire a ground fault would not melt a fuse or tip a breaker.


    I would agree in theory ... but in the real world, older electrical systems such as knob-and-tube which did not have "grounding-type" receptacles were in fact "grounded" by virtue of the grounding electrode system and that all the water piping was metal (copper, galvanized, cast-iron) and (except for the cast-iron) was bonded to ... er ... back then ... "grounded to" the electrical system and, in fact, the metal water piping which went underground was THE grounding electrode and the electrical system was "grounded" to that metal piping.

    And, because almost all the sinks back then were also metal, as were the faucets and riser supplies, the cast-iron drain piping was connected to the metal trap arms and metal traps, which were connected to the metal sinks, which were connected to the metal faucets, which were connected to the metal water piping (*sung to the tune of 'Dem Bones') ... which was connected to and served as "the ground" for the electrical system and which was connected to the neutral at the service equipment ...

    Thus, it is possible ... possible ... that the hot coming into contact with any of those grounded metal pipes could trip the breaker ... all depending on how many joints there were and how well the electrical connection through those joints was unintentionally made. Excellent electrical contact through the joints could trip the breaker, poor electrical contact might just only shock the crap out of you, maybe the resistance of the metal water piping "conductor" would be sufficient to just make you wish the fuse had blown.


    *
    Dem Bones

    Toe bone connected to the foot bone
    Foot bone connected to the heel bone
    Heel bone connected to the ankle bone
    Ankle bone connected to the shin bone
    Shin bone connected to the knee bone
    Knee bone connected to the thigh bone
    ...
    Jerry Peck - CodeMan
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    Construction Litigation Consultants, LLC.
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