What on earth??? I've NEVER seen that system! I worked on many houses that were wired in those days and I found several different wiring methods.
Cloth wire on isolators, either twisted lamp cord or individual conductors for phase and neutral.
Cloth wire directly buried in plaster - groove the wall, secure the wire with a few nails that can be removed later, plaster and remove the nails. Result: the wires are solidly embedded and won't ever move again.
Cloth wire in conduit, two different types. Either only bituminated cardboard or bituminated cardboard with a thin steel sheathing.
And as an additional hack job method 2 with the individual wires wrapped together in news paper and then plastered in.
Both emthods make for nice removal if the plaster is soft - free the end from the box and pull - the wire will come right out and leave a nice groove in the plaster. Not advisable in presence of wall paper, the paper sticks too well and will remove large chunks of plaster.
Then scratch out some plaster with an old screw driver and put in new NYM cable. Minimal effort legal (but certainly not elegant) rewire.
Another nice thing with those old installs is the fact many hacks who tapped into those old installs just ripped up the wall somewhere in the middle of a run, spliced and buried everything in plaster. If the new spur is long and creative enough it gets close to impossible to guess where it actually originates. My dad's office (built in 1914) still has some of those miraculous wiring specialties.
Have a junction box with 2 sets of cloth wires leaving to the right. One is disconnected and used to feed the bathroom. The second one feeds 2 receptacles and a second room.
Receptacle 1 (closer to the junction box) has a feed of 2 PVC wires coming in from above and one cloth and one PVC wire exiting at an approx. 45 degree angle upwards (would lead to the switch box in the room next door). Right in the middle of that run you have a junction box with 3(!) wires just spliced. One is a phase, one a neutral and the third seems to be dead. Exiting towards the switch box: 2 cloth wires.
The switch box in the adjacent room has 2 wires entering, one cloth, one PVC... the feed to the light fixture goes up, but only the switched hot, no neutral...
The next junction box is above the door to room 2. Would be logical if the switch feed, light fixture and receptacle #2 were connected here. Well, not exactly. Box has the feed (2 PVC wires) come in from the left and pass to the right. Second: 3(!) wires just pass through the box from below and continue to the light... only 2 of which reach their destination.
Confused enough?
I don't even want to know what kind of hack job lurks inside that single wall... and exactly how many of them... all I know: a computer and a table lamp plugged into receptacle #2 will have the light dim substantially when the computer starts up.
Not to mention I'm pretty sure there's lots of disconnected sconce wiring still hidden in the room.
Unfortunately the room is crammed full, so there's no way we can rewire it. I'm considering a surface-mount conduit job though to reduce the fire risk.
