I was sistering a joist (over the bathroom) in the attic today. Now the light switch in the bathroom underneath will not work. Any suggestions? I don't see any breaks in the wire. Also, I notice that there is a free wire that is fed through to the bathroom light switch downstairs. It is just sitting there. Is this normal?

Hi: We have a 65-year-old home with the original BX, armor-cable wiring. The wiring is without a ground, and the wire insulation is cloth and very brittle. I'm thinking of replacing the old wiring with new. How likely is it that I'll be able pull Romex through the armor cable? From what I'm able to tell, often a ceiling box is used as a junction to outlets within a room. I was thinking I could disconnect the wires from one of the outlets, tape the Romex to the old wire and pull the wire at the ceiling box, along with the Romex. Has anyone tried this? Do you think I'll get hung up mid-run? Would I have better luck pulling three separate wire? Thanks.