Hacks are around since the days of Edison I guess... the house where I live was wired when it was built in 1914 and it seems already the original wiring was a wild mix of conduit and cloth conduit wire direct buried in plaster, some very creative wiring runs,... sconce wiring plastered over is fairly common too. Usually they only taped the live wires and stuffed them into the wall. No big surprise then when the wall is hot...
According to Terrell Croft, in
Wiring of Finished Buildings (McGraw-Hill, 1915), the "plaster hose" system was commonly used in Austria at that time:
A groove 1 1/2 in. deep is chiseled into the plaster and brick, and a piece of very thick walled rubber hose, greased with soft soap on the outside, is laid in the groove. Th whole is then plastered up and surfaced off smooth. Both ends of the rubber hose, however, extend from the plaster. After the plaster has hardened the rubber hose is pulled out, the soap preventing the plaster from sticking to it. The result is a hole extending under the surface of the wall through which the rubber-covered wires are fished.
This system, however, is now being superseded by the Peschel system, since the latter is only slightly more expensive and much more substantial.
This is from the subchapter of the book that deals with European wiring methods. The remainder of the book is based on US practices of the time.
Incidentally, this wiring method is alive and well in Mexico.
