"David Nebenzahl" wrote in message
s.com...
Have a client with a house built in the '20s, originally knob and tube
wired but (partly) converted to more modren wiring methods. Basement
ceiling is exposed and where the majority of the house wiring is. Lots of
strange, non-standard and some clearly improper wiring exists the
"flying" splices between K&T wiring and NM or armored cable (no junction
box), and one place where someone just ran a single insulated wire (THHN
or whatever) as a neutral from one place to another. Plus exposed K&T runs
going everywhere, one right next to the hot-water shutoff valve.

So I've figured out pretty much what goes where and how to replace it
(mostly with runs of Romex, since it's not an occupied space).

But there's one thing about the old wiring that's puzzling to me. Usually
K&T runs are done with pairs of wires (Hot & neutral) running alongside
each other, and in most cases that's followed he a run up into a wall
will have a pair of wires going up into the subfloor.

But there are a couple of places where a *single wire* is routed up out of
the basement into the house above. In these cases, the wires are all hots.
No corresponding single neutral wire anywhere nearby. Presumably the
neutral side of the circuit is tied to the neutral of another pair of
wires.

This, of course, makes it difficult to map these circuits, since I can
only assume that the neutral connection is made to the neutral wire
corresponding to the hot wire. That's my operating assumption, anyhow: my
plan is to simply replace these single-wire runs with Romex, using only
the black wire. (Hmm, wonder if they make 12-1 Romex w/o ground? Probably
not.)

Anyone ever seen this situation in an older house?

--
Found--the gene that causes belief in genetic determinism

You need to ring it out and see where that conductor goes. It's probably
going to a switch, who's return takes another path. Check outside lights,
hall lights, or things like the oil burner , that may have an emergency
switch in the main house