The electrical breaker boxes for our house were updated in 1973, according to a receipt we found in the basement. Conduit to power extra outlets / light bulbs was strung along the basement ceiling at the same time. While the boxes were professionally installed, it looks like the previous owners added the conduit themselves. (It looks like a hack job and wasn't on the receipt.)
We're considering upgrading the service and having the basement rewired. So we peeked into some of the connecting boxes and were horrified at what we discovered. Our best guess is that the electrician left behind a pile of old cloth wire that was removed during the breaker boxes upgrade, and the previous owners decided to reuse it in new connector boxes. That's 1920s wire going through 1970s boxes.
Old cloth-wrapped wire going through sharp-edged conduit.
Old, uncapped wire, held together only with old tape.
Oh, yeah, we're going to have to remediate this sooner rather than later.