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Knob and tube wiring

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  • Knob and tube wiring

    I know this isn't a "woodworking" question, but I figured someone here can answer a question regarding knob and tube wiring. I want to install a ceiling fan into a room in my house, however, I have knob and tube wiring. With the ceiling fan I (obviously)have the three wires (black, white, and blue). How do I connect the three to the two? Should I connect the blue ground wire to the electrical box? Or can I connect the blue ground wire to the neutral line as well? I need help.

  • #2
    If i am not mistaken the black wire is hot for the fan motor, the blue wire is hot for the light kit and the white wire is common/neutral . There should be a green or bare copper wire that needs a ground for safety which is the problem with knob and tube ... no ground. You will have that problem with every new fixture or appliance you buy. The only way to solve the ground problem is to rewire the house or run a ground wire from your cold water pipe (assuming its copper and buried six feet below grade) to the fixtures or appliances that need a ground, may be easier to just rewire. If you are not familiar with wiring it is likely safer to ask for help or hire an electrician. Your saftey / life is worth more than the most expensive electrician.


    • #3
      I have made the decision to call a professional. Like you said, I don't want to risk anything. I have two fans I want installed, so it would be easier (and safer) in the long run if the electric in the rooms were updated.


      • #4
        1. You should really think about replacing that knob and tube wiring. It isn't code and it isn't safe. In fact, your electrician may decline to hook anything up to it.

        2. If you are installing a ceiling fan, the first thing you have to do is be sure the box is rated for the load of a fan, which is much higher than that of a light fixture. You just can't replace a ceiling fan in a light fixture box.

        3. As for the color coding of the wines ON THE FAN, you have to rely on the instructions that come with the fan. I think wbrooks is right, but I wouldn't bet on all fan makers doing it the same way. (If you don't have the instructions, you can do this: open up the wiring container. You'll have two pull switches and one slide switch. One pull is for the fan (and has 4 stops: lo, med, hi and off); one pull is for the light and is SPST; the slide switch is for reversing the direction of the fan. If you follow the wiring, you'll see that power for the fan (i.e., either the hot or blue, in your case) goes from the feed, to the slide, to the pull, to the motor, while the wire for the light goes directly to the pull and then to the light socket.)

        4. Since you're hiring someone, I won't tell you how to test which wire on the k&t is hot.

        [ 04-19-2004, 05:22 PM: Message edited by: RGad ]


        • #5
          OK, stupid question, but what the heck is Knob and Tube wiring??



          • #6
            Found fairly often in houses built before 1930, "knob and tube" wiring should be carefully inspected to failed insulation and other safety issues. If it has adequate capacity and is otherwise safe, it is still legal in many places.

            More info than you likely care to know *search link*


            • #7
              Knob and tube was the first household wiring. My last house was built in 1904 and it had it. Hard to find a place that would cover the home owners insurance. It is an ungrounded system. It consists of 2 insulated solid copper wires that are run separately. The wires travel around corners over ceramic/porcelan insulators (knobs) and travel through the joists also in additional insulators (tubes). We had the entire house rewired to current code. The electrician took about a month off and on to complete the job. Fished all the wires, minimal destruction. It cost about 5K for a 2,000 sf home. We were able to increase the outlets from 1/room to current code + many other extras (phone/data), 200 amp service, breakers from fuses. It was a great selling point when we sold.



              • #8
                one bad thing about changing is you loose those great looking push-knob switches that really add to a arts and craft style home, but I know safty first just wish they made retro switches bill


                • #9
                  I had an electrician come over and look at the wiring. He said that since most of the knob and tube is between the walls, protected from moisture, it should be ok. Since he said it was in good shape, he would run new romex from the wall switch to the ceiling. He said he just needs to connect the romex to the hot connection. Again, he told me that it's ok to have knob and tube if the wires are in good shape.