SPOOL OR KNOB TYPE

The Lenin insulator factory was located in Nikolaevo, Bulgaria, starting production during the communist era in 1953. The factory still exists today as Elpo Ad (Елпо АД) and still manufactures a full range of insulators. Spool or Knob insulators usually have a non-spiral hole in the center for mounting, usually on a wall, and a wire is wound around the outside. These insulators are final, they are used at the end of the wire. They are often placed on bases on the sides of buildings where cables enter the building.