I'm trying to replace some - not all - of the knob and tube - basically where walls are open. There isn't much left and this may actually be the end but my immediate pondering is determining which is actually in use. The apparent total lack of logic or organization of knob and tube wiring not withstanding, you can only
trace it till it goes out of site, which is anywhere the original plaster and
lath is still good. Will a
voltage sniffer indicate
wire in service, even if no load on it?
A
voltage sniffer will indicate
voltage and at times my Fluke has indicated down to lower
voltage even if not rated so. Could be important given resistances of old circuits in wiring. A good
plot of all
circuit breakers in where they relate to all outlets of what ever type in the building would be the better start for this and long term use. Dependant on the building in outlets not known about or
etc., a good
voltage sniffer, some various screw or
plug type adaptors
etc. for it to
plug into
etc also for connecting CB sniffers also. Study and
plot of the
power panels and where they by radio with an assistant at times if large enough a building.... "it's out,.. no go back" type stuff is the best starting
point in plotting out the
system in what
breaker controls what. Than as you have walls exposed as you
express, certainly if in the area this might be going to you have control, and use the sniffer to check if these wires are what you think they are. Possible they are for some
outlet not found yet also so good to check.
At least from my last 1999 reading of the code, Knob and Tube while normally 14ga thus only 15A I would downrate, was still viable though not recommended. I believe next year comes out the next code
book and I am already approved of work buying for me the Handbook expanded verseion for me to study. Grew up in a very old
house with exposed knob and tube running all
thru the basement but I think much of the rest run
thru Sch 40 gas pipe at least to some areas to replace the gas lights.
I would map/
plot out the building first before I did any work - simply because I/you can, and work from there.. What's in use you now have a map to what it might be connected to or what it might be going to in
circuit breakers that now this
voltage sniffer indicate in turning offonce the mapping is done and if not related to known outlets perhaps indicate something not known about to
trace.
Were this
circuit not something known as to where it goes or what
breaker controls it, you than have a problem in all ways. Map out first is my recommendation and I on site normally wear the
voltage sniffer on my shirt collar in just to remind me to check when ever I do something, everywhere and often. If something does go wrong though... I made a mistake in my research of the curcut which can happen. Checking often and aways can save you from just like three months ago for me... thought I completely analized this wiring, nope it was
power coming in from here instead of there. That's odd for even a 1972
house how they wired it.