It has been fascinating to see the old Knob and Tube wiring, with its supply and return wires run separately. This type of wiring was becoming standard in North America around the time our house was built and, apparently, was still being installed in some NY buildings until the mid 1970’s.
Rather than explain it in this post, here’s a couple of interesting links:
Wikipedia
https://en.wikipedia.org/wiki/Knob-and-tube_wiring
Inspectapedia
https://inspectapedia.com/electric/Knob_and_Tube_Wiring.php
We also found some old fabric-covered wiring in the basement.
