Quote Originally Posted by JLMCDANIEL View Post
Not sure how it is in your area but out here in the wilds that was wired by the REA, it is quite common to find "that kind of wiring" in plaster and lath homes. In fact it is more common than K&T unless you are in the city.
Around here I see bx behind plaster lath more often then nm, obviously both practices were in use at the time, just dont see much of it, I suspect at the time there may have been some local bias toward the bx wire and away from the nm. Personally I think the bx can be worse then the knob and tube.

there absolutely right if it is plaster lath open the floor.