Hello all, I am new here and to forums in general. I am also newer to the Knob & Tube wiring. My family farm house, which I recently bought, is primarily k&t wiring with the addition of some 12-2 or 14-2 wiring in the past 10-15 yrs.

In one of the bedrooms there is still the pull chain style, single light bulb, fixture. I have removed the fixture to replace it with a new one. I would like to add a light switch to this room to be able to use this new fixture but I haven't been able to find a difinitive answer as to how to wire this new switch in with new romex wire and attach it to the k&t wire that is in place as the supply.

I hope that I have explained this in enough detail and clear enough to understand. And thank you in advance for anyone that can possibly help me out.

Wyatt

You need to instt a "switch loop". Cut a hole for the wall box. Run a piece of romex to the fixture. Find the hot lead into the ceiling box and wire nut that to the white wire from the wall box.. Connect the black wire from the wall box to the to the black light wire and other neutral wire to the white for the fixture. Mark the white lead from the wall box with black tape or magic marker. Install an old work box, a single pole switch and connect the black and white wire to the switch. Mark the white wire with black tape or magic marker. Install the switch, power on and you should have a wall switch that now controls the new light.

I think that I understand now what I was doing. I won't have time tonight to try it out but will try it tomorrow night. Thanks & I will get back to you when I find out if I truly understand or if I need further help. It sounds easy enough but we will see if this novice will get it straight.

I haven't worked on knob and tube wiring before, that is some old stuff! But I have seen my fair share of it in the field. Is this k&t wire aluminum or copper? If aluminum then joining it to romex/copper would be a no go unless you use specific connectors like alumiconn connectors or copalum connectors. Most I am aware of uses a copper conductor but you never know with these old systems and I wouldn't take it for granted that it did. You will also want to be sure not to cover any of the existing k&t wiring with insullation in the attic or walls because k&t depend on air to cool and the added insullation can supposedly create heat issues. Adding a switch as you have suggested isn't a big problem, however, you noted that there has been new wiring added to the structure in the past 10-15 years. Your home is most likely on a 60 amp service and adding to the k&t wiring can cause excessive heat issues and overloads. The wiring in itself is fairly safe if it is in good shape but adding to the load or covering the wires can create a fire hazard. Also be careful with the insullation on these old wires as some of it may contain asbestos and when disturbed may become friable.

Thanks for the heads up on the asbestos. I should have thought of this being I work in an engineering/building related field. The house has a 200 amp service panel, not sure when that was added, sometime in my parents time I am sure. Also there has been some other Romex added to add switches to the other bedrooms up stairs. From my best observation this has been added to the K&T wiring as well. I do know that this is copper K&T so I am better off in that sense. There is already insulation of sorts in the attic, been there at least all of my 33 yrs of existence. There is two different types though, some foam cubes about 1"x1"x1" and the other type is fiberglass insulation of some type. Thanks for all the thoughts. I hope to in the near future start replaceing the entire house wiring to romex but that entails busting into all the walls and those are lath and plaster so an even bigger expense to replace as it will be very hard to patch and match.

Well lets hope the addition of the 200 Amp panel was to provide additional amperage for the modern appliances and mechanical systems and not to increase the load on the smaller branch circuits. If they added some 12-2 and 14-2 romex then hopefully that was used to take some of the load off the present k&t system. Another note about the k&t wiring is that many times it will appear to be 12awg wire by it's size in some places but back then when they drew wire the uniformity in diameter was not as precise as it is today. Many times the wire is actually more like 14awg possibly less in some places and as a result will have a rating of it's smallest diameter in the wire. Something to also be wary of in this k&t system, is that some of the wiring practices way back then used the neutral wire as the switching wire and sometimes the receptacle box still has a hot wire when the switch is turned off. So to be on the safe side throw the breaker and check all wires for voltage before working on them.

Thanks for the great explanation. The "loop" worked perfectly. Sorry for the time lapse in getting a response back on here but I finally had enough time to get to it this weekend.

See how good you are! Rock on DIY'er. The only shortcoming of K&T is the lack of a ground. You can use a GFCI but have to mark it with a No Service Ground sticker. Make sure to use these in bathrooms, kitchens and other places even if you are grandfathered.