Most everything in the early days was made of wood for incandescent lighting (1879-1882 for socket shells, after which porcelain, brass and hard rubber was used). Incandescent lighting in the early days did not require the high amperage that ARC lighting did until series and high amperage started being used.
Edison's first socket in 1879 was carved out of wood and the terminals were on the outside of the socket (shown below). In 1880 he started bringing the wire down through the center of the socket.
Wood parts (wall plates, rosettes, switch bases, test socket bases, etc. continued being made until about 1893 when most manufacturers started using porcelain as a standard.
1880's Walls
Linear Mode
