A friend asked me to rewire his small store. Early 1900's building and they lived in an apartment on the second floor. I told him we would tear out the old knob and tube for the store and puit in a new box.
Went down in the basement and pulled all the fuses for the store circuits. Disconnected all the hot wires and what I thought was the neutral (weren't any grounds).
Went upstairs to start removing outlets. And promptly got shocked!! Turns out that there was ONE common neutral for the whole building. One heavy gage BARE copper wire ran thru the whole building and all the neutrals were soldered to it.
Fortunately he had pulled most of the plaster off the walls to remodel so I was able to find the connections and cut them so I could take the rest out. Never did figure out what the wire was that I thought was the neutral and disconnected.
