On Sun, 24 Nov 2013 17:27:26 -0800 (PST), bob haller
wrote:

unmolested K&T is marginally ok. but tapping into it, modifying
it, can add new hazards. a good friend had a small home fire where a
solder joint detoriated and overheated, fortunately he cauht it just in
time. it was smoldering he could of lost the entire house. his dad had
soldered that joint over 30 years ago....

which is why i said just replace the entire thing..... all the 3 way
light switches etc, that the OP said he had intentionally miss wired

-------

Yea, but he's not tampering with the actual wires, just moving them
around inside a box to get them on the right screws on the switches.

That solder joint was apparently not soldered well in the first place.
Soldered wires were some of the best connections made, if they were done
properly. I also would bet that they had a 30A fuse in use on some #14
wire, and had plugged in an electric heating device.

When I had to tap into existing K+T wiring on my jobs, I would install a
box and use wirenuts. But on a few jobs, I did also solder them when it
was impractical to install a box, such as in an attic where the wires
did not provide enough length to use a box, and I only needed to add a
tap to provide another light. I'd just bare the wires, attach some
romex, and solder them and apply tape. Safety was always a main
concern, but customers were not willing to pay to have their whole house
ripped apart, and repaired just to add a ceiling fan or some track
lights.

By the way, here is another tip I forgot to mention. Colored heat
shrink tubing works great to color the wires the way they should be.
Costs a little more than tape, but is real easy to use, and even
protects the wires from fraying on their ends which that old cloth wire
was known to do.