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  1. #1
    Join Date
    Jan 2008
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    Cleveland, OH
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    Default Knob & Tube meets NM

    I have a wall switch box with 3 switches, each controlling a different light fixture. The box is powered by one hot that is pig-tailed off and connected to each of the 3 switches. The wiring is all K&T.

    I am replacing 2 of the 3 fixtures including wiring 12/2 from the fixtures back to the switch. Also, I am running 12/2 from the service panel (15 amp breaker) to the switch box. This means that for 2 of the 3 fixtures, they will be brand new Romex from service panel all the way through the switches to fixtures. What I'm left with is the third fixture, which I am not touching. Which leads me to my question:

    Can I run 12/2 from service panel (15 amp breaker) to a switch and then leave the K&T wiring from the switch to the existing fixture? If so, do I have to be concerned with the old K&T neutral in any way?

  2. #2
    Join Date
    Jun 2007
    Location
    Shamokin, Pa.
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    645

    Default Re: Knob & Tube meets NM

    I would be surprised to find a neutral wire in the wall switch box. As with knob and tube wiring the neutral never had to go to the switch box to begin with.
    Is one present in the box, or are you able to locate it somewhere else?
    That may be your biggest problem.

  3. #3
    Join Date
    Jan 2008
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    731

    Default Re: Knob & Tube meets NM

    Quote Originally Posted by b_r View Post
    I have a wall switch box with 3 switches, each controlling a different light fixture. The box is powered by one hot that is pig-tailed off and connected to each of the 3 switches. The wiring is all K&T.

    I am replacing 2 of the 3 fixtures including wiring 12/2 from the fixtures back to the switch. Also, I am running 12/2 from the service panel (15 amp breaker) to the switch box. This means that for 2 of the 3 fixtures, they will be brand new Romex from service panel all the way through the switches to fixtures. What I'm left with is the third fixture, which I am not touching. Which leads me to my question:

    Can I run 12/2 from service panel (15 amp breaker) to a switch and then leave the K&T wiring from the switch to the existing fixture? If so, do I have to be concerned with the old K&T neutral in any way?
    connecting it is the concern. K&T has to be soldered connections in junction boxes. How are you planning on connecting it to the NM? Wire nuts are out.

    If you are rewiring a circuit do the whole thing.

  4. #4
    Join Date
    Jun 2007
    Location
    Fayette County, Ohio
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    5,558

    Default Re: Knob & Tube meets NM

    Why run a separate circuit for the third switch? Just cap and tape the K&T power wire or disconnect it at the source, then jumper the new black from one other other switches. You could then leave the top of the switch and the fixture wired as is.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  5. #5
    Join Date
    Jun 2007
    Location
    Fayette County, Ohio
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    5,558

    Default Re: Knob & Tube meets NM

    Quote Originally Posted by Blue RidgeParkway View Post
    connecting it is the concern. K&T has to be soldered connections in junction boxes. How are you planning on connecting it to the NM? Wire nuts are out.

    If you are rewiring a circuit do the whole thing.
    I have to ask, on what foundation do you base your first statement?
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  6. #6
    Join Date
    Jan 2008
    Location
    Cleveland, OH
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    16

    Default Re: Knob & Tube meets NM

    Quote Originally Posted by Ernie_Fergler View Post
    I would be surprised to find a neutral wire in the wall switch box. As with knob and tube wiring the neutral never had to go to the switch box to begin with.
    Is one present in the box, or are you able to locate it somewhere else?
    That may be your biggest problem.
    Yes, there is no neutral in the switch box, but what I was actually referring to was the neutral at the fixture. I would be supplying a new NM hot to the switch box, the hot would be pig-tailed to three switches with one of those switches still connected to K&T from switch to fixture.

  7. #7
    Join Date
    Jan 2008
    Location
    Cleveland, OH
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    16

    Default Re: Knob & Tube meets NM

    Quote Originally Posted by JLMCDANIEL View Post
    Why run a separate circuit for the third switch? Just cap and tape the K&T power wire or disconnect it at the source, then jumper the new black from one other other switches. You could then leave the top of the switch and the fixture wired as is.
    Jack
    Exactly. This is what I intended to to -- I just wanted to make sure that I could have one end of the switch (from power to switch) NM, while the other half of the switch (from switch to fixture) be K&T.

    -Brad

  8. #8
    Join Date
    Jan 2008
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    731

    Default Re: Knob & Tube meets NM

    http://www.markhellerelectric.com/wusplice.pdf

    How-to's with citations diagrams. Local rules vary greatly even from towns to towns, and personalities of individual inspectors in the same office! Your homeowners insurance may have an opinion also. Ours voided coverage if any K&T circuit was modified, and defined repairs differently (more restrictive then the NEC), and required entire circuit be removed and replaced if any alteration other than specific defined repairs of the original circuit was made. When we replaced panels we were required to decommission ALL of the K&T.

  9. #9
    Join Date
    Nov 2007
    Posts
    980

    Default Re: Knob & Tube meets NM

    hummmmmm interesting. I don't think I have ever heard of insurance companies doing an inspection on a remodel unless it was due to fire damage or other insurance claim.

  10. #10
    Join Date
    Jun 2007
    Location
    Shamokin, Pa.
    Posts
    645

    Default Re: Knob & Tube meets NM

    Quote Originally Posted by Blue RidgeParkway View Post
    connecting it is the concern. K&T has to be soldered connections in junction boxes. How are you planning on connecting it to the NM? Wire nuts are out.

    If you are rewiring a circuit do the whole thing.
    Inaccurate information provided here. Please Google again.
    Of course you can wire nut K&T and Romex, in any approved J-box.
    Last edited by Ernie_Fergler; 09-27-2008 at 02:23 PM. Reason: spell check

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