Joining Knob and Tube wiring to new wiring

[Anonymous]

Posted by: Ylric (old forum transfer)
Mon Jul 08, 2002 10:15 pm

Hello all,
Looking for a little advice on how to join Knob and Tube wiring with new wiring. Trying to install a ceiling fan in place of a hall light but the hall light was wired with K&T and is on a 3 way switch. What I would like to do is join the new ceiling fan light (light only) to these 2 leads from the knob and tube. Question is, what is the best way to do this? The insulation is brittle (house is close to 100 yrs old) but it is good to the first set of knobs - just kind of brittle at the end.
What I was thinking of doing is putting a junction box and joining them in there, but I don't think I have enough wire in good condition to do that. Is it possible to use 2 junction boxes - one on each side? Of course, this would mean that the new wiring coming out of that box would only have one lead used. Any advice would be most appreciated. (yes, I would really like to pull that knob and tube back to where it comes out of the wall for the switch.. but I don't think I am up to spending that much time in the attic in 100+ heat)

Also, I see a bare wire running all over the attic, it is not connected to any knobs or tubes but it is strung from one end to the other and tied of with what looks like an insulator. Wierd thing is, all my outlets DO have a 3 prong plug and according to the little plug in device I have, they are grounded. Could this bare wire I see be a ground that they added at a later date?

[Anonymous]

Posted by: Wgoodrich
Posted: Mon Jul 08, 2002 11:06 pm

You really need to do your connections in the attic eliminating the brittle part of your knob and tube. The brittle part of your knob and tube is most likely wiring that was exposed to a light fixture that had too large of bulbs installed in that light fixture creating excess heat in that light box.

If you light box is in that attic coming through your ceiling you should remove that light box and install a remodle style box listed and labeled to support a paddle fan. These are called remodle fan boxes. These fan boxed do not rely in the tabs where you existing light box has its screws threaded into. These fan boxes have threads in the back of the box with the tabs having those screws slide through those tabs then screw into the back of hte box. Reason for that design is to limit the vibration of that fan from destroying your light box threads and the fan crashing down due to failed light box threads.

To take care of your knob and tube wiring that has been damaged you can do a lot of your prep work before you get into the attic.

Take two nail on plastic boxes and run a piece of romex for each part of the knob and tube you want to replace and place them stripped in the two nail on plastic device boxes. Then go into the attic. MOst likely you have more than one set of knob and tube wires in that light box. That is ok. Just replace each wire running from that light box with a new romex to the point you want to join to your knob and tube wires. Make sure this is a comfortable location to work. Then cut you damaged part of your knob and tube in two and throw away that damaged part. Then slide the ends of the knob and tube wire into the plastic device box and wire nut the new romex to the old knob and tube wiring inside that plastic nail on device box. Be sure to install your knob and tube wires into that plastic box long enough about 6" to make your wire nut connections. Once you have spliced the old knob and tube wire to the new Romex then nail the plastic box so it stays above insulation and screw on a plastic blank plate. Repeat the same actions on the second junction box. The other ends or the new romex stick into the light box stripping the outer sheath about 6" back. Then get out of the attic and have a cold one and think how nice it was that it only took about 10 minutes to do it right.

If you think it ahead and take everything up with a helper to throw you what your forgot and you will forget something, and strip your wires before you enter the attic knocking out the hole in the boxes that you need then enter the attic you can be done before you know it. Good luck and let us know how you come out.

Hope this helps

Wg

[Anonymous]

Posted by: Ylric
Posted: Tue Jul 09, 2002 7:41 am

thanks Wg,

any idea what those bare wires are that I saw running the length of the attic?

also, where the old light fixture was was inbetween two ceiling joists. It was hung on an "L" shaped piece of wood with the old K&T coming through the back and out the bottom and the light fixture hung from the bottom of the "L". What I did is cut that piece of wood right out. Now I have room to add a solid 2x4 with a box screwed right onto it. Gonna check for the fan box you mentioned though as it does sound nice to have more thread where the fixture hangs (the fan I have comes with 2-3" wood screws that are suppose to go beside the box into the joist for additional str.)
Well, back into the attic tonight.. after I pick up some cold ones !

[Anonymous]

posted by: Wgoodrich
Posted: Tue Jul 09, 2002 7:24 pm

YOu can buy many different style of fan boxes one should meet your needs. YOur fan must be the heavier type that uses alternative support methods. YOu could use a fan box pancake style the the wood screws screw straight through the box into the wood and the box contains the splices.

Teh bare wire you are speaking of strikes three possibilities in mind.

If this wire is a 14 awg bare wire it could have at one time had insulation that turned brittle over time and the insulation pealed off. Make sure those wires are dead if this is the case.

If you have 8 awg braided bare wires it could be a lightening arrest system where lightening rods either were or are installed on your home.

If you have 12 or 14 single bare wires someone may have attempted to install an equipment grounding system to a two wire electrical system. If this is the case these wires should be entering the receptacle boxes somewhere. If this is the case they also should have used green insulated equipment grounding conductors instead of bare conductors.

Good Luck with your project and let us know how you come out.

Wg

[Anonymous]

Posted by: Ylric
Posted: Fri Jul 12, 2002 6:26 pm

Ok.. I am all messed up here..
The original fixture had 2 wires running from it. If I touch my ac tester to the one wire, the tester glows, telling me that it is the hot wire. There is no glow when I touch it to the other wire, so that one is neutral then right? It looks like the switch is wired to the neutral side (3 way switch) is this right?
So now, I want the wall switch to turn on the light on the fan, and the pull chain to operate the ceiling fan. On the fan, I have a black, white and blue wire. According to the instruction sheet, it tells me that the blue wire should connect to the wire coming from the wall switch, and the black and white to black and white respectively. But does that mean I need to run another hot wire to the fan then? so confused...

[Anonymous]

posted by: Wgoodrich
Fri Jul 12, 2002 7:15 pm

You should have had originally an old black and white wire in that existing light box that connected to the fixture black and white wire. If this his true then you cut out the damaged wires and extended the matching color wire into the fan box you should still have a black and white wire in that fan box.

Connect the black and blue wires of hte fan to the black wire coming into the light box. Connect the the white wire of the fan to the white wire of the wire coming into the fan box. You switch will control both on and off of both the fan and the light by the same switch.

If you wish to have a separate control for the fan separate from the light then you will need to install a second switch with a new power source or replace the wires coming into the light from the switch with a cable that contains a black red white and bare wire in it with power in that switch then install two switches at the switch box location.

If you have more than a single black and white wire coming into that fan box then the power may be at the fan box instead of at the switch. IF so tell us then we must come up with a wring design different from the above advice.

Hope this helps

Wg

[Anonymous]

posted by: Ylric
Posted: Fri Jul 12, 2002 7:38 pm

ok.. the way you suggested is the way I have it wired now. But the problem is, the original light fixture was on a three way switch (the light is at the top of a staircase, one switch at top of stair case, one switch at bottom) Now, the switch cuts the power to both light and fan - but I only want it to control the light.
Using my tester, it looks like the 3 way switch is wired on the neutral side of the wiring. I had the power on and put the tester to the wire. The one wire made the tester glow regardless if I turned the switch on or off.
The wire that made the tester glow I took as the black wire and wired the blue and black to that. The other was connected to white.
Now, if I wanted to make it so that only the light works with that switch. I would take the blue fan wire to the white wire from the ceiling, the black wire from the fan to the black wire in the ceiling and take a new white wire to the white wire in the fan box? The thing that is confusing me is that I have a switch on the feed to the ceiling fixture, so I need to seperate the feed into the switched feed for the light and a non-switched feed for the fan.. no?

[Anonymous]

Posted by: Wgoodrich
Posted: Fri Jul 12, 2002 8:02 pm

Now I need to know for sure how many cables are in that fan box and what color conductors as best you can see in each cable and how many conductors are in each cable in that fan box. Then I can better tell you the answer you seek.

I am suspecting that you have reversed polarity on that fan right now by the way you discribed your tests and your connections.

A neon tester will register a white grounded leg that has what is considered as transient voltage or gohst voltage. Remember the NEC forbids white wires to be switched. Unless you had an electrician that didn't know this then your switch will by controlling the hot not the neutral. A switch controllig a neutral was a code violation even back in the knob and tube time era.

Wg

[Anonymous]

Posted by : Ylric
Posted: Sat Jul 13, 2002 11:44 am

no colours on the wires.. old knob and tube all looks black. The way I was figuring which was hot was with the neon tester, as I figured it would glow with the hot wire. For example.. if I went to a modern home and saw a black, a white and a green, the neon tester would only glow on the black wire right? So in my case, I took that as the black wire, the one that made the tester glow.
But if that is the case, then the original 3 way switch is wired on the other wire. With the power on, I had the neon tester on the glowing wire side and flipped the upper switch, the neon tester stayed glowig, so I figured the switch must break the circuit on the other wire.
Like this I think
-----: =switch=:----------- (no glow, must be white)
---------------------------- (glow on tester=black wire)
Again, this is old knob and tube so who knows how they wired a 3-way switch then. This circuit also controls the 2 ceiling lights in each bedroom across from hall, and it lloks like (from in the attic) that the one wire that glows with the tester, runs the length of the attic to each of those lights

[Anonymous]

Posted by: Wgoodrich
Posted: Sat Jul 13, 2002 6:28 pm

If you are sure you have a neutral on the switch system in all that branch circuit maybe someone misidentified the wire colors in the panel. If you are positive your polarity is reversed then go the the panel and reverse the wire in the fuse with the wire on the neutral bar of that branch circuit. This would change the polarity back so hot is being switched. Just make sure you are correct that the grounded leg [aka neutral] is the one that is being switched right now in the entire branch circuit. Sounds like someone misidentified hot during a service upgrade project.

Switches are very dangerous when controlling the neutal conductor the NEC forbids switching a neutral or grounded leg [aka neutral]

Wg