I owned a house in Seattle built in 1910 that was originally built without electricity, so it had gas pipes running around in the walls and ceilings. The houses in that area were originally built for the day-workers at the Gas Works down the street (now called Gas Works Park), where they gassified coal for use in lighting and heating in the city, so it stands to reason that even at the dawn of the electrical age, the gas works company was not promoting electricity to their workers. Electricity was added to the house later; probably in the 20s with K&T run as MWBCs everywhere and far too few outlets and fixtures. The original fuse panel was upgraded to a breaker panel, from the looks of it some time in the 60s, when they added electric baseboard heating. The electrical system was a complete mess though, both upgrades appeared to have been done by homeowners at the time. Lots of crazy stuff like uninsulated wires run in the walls (with maybe 8-10" of separation, but still...)
