I found this during my barn wiring method research...
"In the early 1930s when farms were being wired in great numbers, the only type of nonmetalic cable then made(now known as Type NM)was generally used in the wiring of farm buildings including barns.
It gradually became clear that the usual high humidity and corrosive conditions in barns caused quick rotting of the cable. The outer fabric jacket and the fillers in the cable acted as wicks, drawing moisture into the inside of the cable. With this deterioration came the danger of shortcircuits or shocks and fires.
It became necessary to rewire many farm buildings after only a few years because of the short life of the cable.
This led to the development of what was first called "barn cable",and which has now been standardized as Type NMC nonmetalic-sheathed cable. Later, underground feeder cable Type UF was developed.This too is suitable for wherever Type NMC(or Type NM) is otherwise used."
Seems that Type NMC nonmetalic cable was developed for barns and when UF was invented, it became the cable of choice leading to manufacturers of cable dropping it from production...
shortcircuit
