Original electrical trade vintage catalog for JEFFERSON ELECTRIC COMPANY. Main office and factory was located in Bellwood, IL. Saf-T-Lag thermal fuse protects wiring and equipment against short circuits, prevents damage to panel and switchboard. Mercury lamp transformers designed to govern the current through the starting and operating cycles of mercury lamps. Disbound from a large 1949 electrical construction materials book, this unique old one page technical specifications brochure would display wonderfully matted and framed. A marvelous addition to your retro electric equipment library.