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jadrma 11-18-2008 02:47 PM

expanding knob & tube wiring
 
I'm remodeling my bathroom and there is a single switch operating a ceiling light. I would like to add a ceiling fan on an adjacent switch. Since it's knob & tube, their is only a hot wire going to the existing switch and then up to the ceiling light. From the light it travels back to the neutral line in the attic. Seems like I can add an additional switch by splicing (wire nut) into the hot wire before the original switch and connect it to the new switch (I'll install a dual swicth electrical box). Then I'll run a hot wire from the new switch to the fan and from the fan run a line to the existing light and splice into the existing line leaving the light (acting as the neutral). Is my logic correct??

rgsgww 11-18-2008 02:59 PM

Quote:

Originally Posted by jadrma (Post 186873)
I'm remodeling my bathroom and there is a single switch operating a ceiling light. I would like to add a ceiling fan on an adjacent switch. Since it's knob & tube, their is only a hot wire going to the existing switch and then up to the ceiling light. From the light it travels back to the neutral line in the attic. Seems like I can add an additional switch by splicing (wire nut) into the hot wire before the original switch and connect it to the new switch (I'll install a dual swicth electrical box). Then I'll run a hot wire from the new switch to the fan and from the fan run a line to the existing light and splice into the existing line leaving the light (acting as the neutral). Is my logic correct??

You cannot extend ungrounded circuits. Is the line with the neutral in the attic grounded?

jadrma 11-18-2008 03:44 PM

expanding knob & tube wiring
 
Yes, the neutral runs in the attic are grounded at the 100amp Service Panel.

joed 11-18-2008 03:52 PM

Since all neutral wires are grounded at the panel let's ask that question in a different manner. Are there three wires including ground at the light fixture?

jadrma 11-18-2008 04:18 PM

expanding knob & tube wiring
 
No...this is knob and tube so there is only a single wire (hot) to the wall switch which then travels to the light fixture. That same wire then travels to the attic and ties into the parent neutral line which runs back to the grounded service panel. Only a single wire makes up the circuit.

rgsgww 11-18-2008 04:26 PM

Quote:

Originally Posted by jadrma (Post 186925)
No...this is knob and tube so there is only a single wire (hot) to the wall switch which then travels to the light fixture. That same wire then travels to the attic and ties into the parent neutral line which runs back to the grounded service panel. Only a single wire makes up the circuit.



You have two options, install 14/2 with ground to the main (15 amp) or 12/2 with ground (20 amp) or not install the fixture at all.

If you decide to run wire you must read up your local code amendments...they may require certain methods (like conduit and type ac cable).

jadrma 11-18-2008 06:01 PM

Thanks for your help. I think I'll go ahead and get a bid on replacing the 100amp panel with 200amp and replacing all of the old knob & tube wiring.

AllanJ 11-19-2008 09:47 AM

(While replacing all knob and tube wiring is recommended everywhere, in most places this is not mandatory even if you upgrade the panel. So you might choose to have a professional upgrade the panel while you replace wiring yourself at your convenience.

As you need new wiring work at the bathroom light switch, you might as well, if you do it yourself, rewire the bathroom light and decommission that part of the knob and tube wiring at the same time you install the fan. Instead of having both the new cable feed for the fan and the old K&T feed for the light entering the same switch box.)

bradnailer 11-19-2008 10:21 AM

I feel your pain. I renovated a 100 year old house with knob and tube wiring. The first thing I did was drop in a 200 amp panel then gradually rewired the entire house as I renovated rooms.

jadrma 11-19-2008 11:26 AM

How do I change out my K&T wiring room by room? Is there a way to transition to 12-2 or 14-2 by splicing into the old wiring or do you have to make the change all the way back to the Service Panel thereby replacing the entire circuit and everything it operates?

rgsgww 11-19-2008 12:37 PM

Quote:

Originally Posted by jadrma (Post 187237)
How do I change out my K&T wiring room by room? Is there a way to transition to 12-2 or 14-2 by splicing into the old wiring or do you have to make the change all the way back to the Service Panel thereby replacing the entire circuit and everything it operates?


You would have to rip it all out and run new. I would recommend not doing it yourself if you do not know much about electrical (multiwire branch circuits, ampacity, etc.)

AllanJ 11-19-2008 05:05 PM

You start re-doing each circuit by running the new cable from the breaker box. You may follow the route of the K&T hot wire from one receptacle to the next but you should add more receptacles if needed to meet code. (Typically 11 feet apart or so that a 6 foot cord from a lamp standing anywhere against the wall can run along the wall and reach a receptacle without crossing a doorway.) You may decide that two new circuits are needed to cover all the rooms that one circuit served years ago. If the K&T neutral goes back to the panel via another route, you do not need to continue running cable from the last receptacle that way.

There are special rules for circuiting kitchen, laundry and bathroom receptacles, including having separate circuits of 20 amps each.

mattedfred 11-19-2008 05:27 PM

get 3 quotes from licenced electricians on replacing the panel and as many circuits that you can access without punching dozens of holes in the walls. i would also consider a 125 amp panel as it is cheaper than a 200 amp which you probably don't need anyway. we did this in our previous house and got rid of all but 2 W&K circuits.


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