Zinsco was a manufacturer of circuit breakers and electrical distribution panels, founded by Emile Zinsmeyer and his son Martin Zinsmeyer in the early 1930s. Originally the West Coast division of the Frank Adam Electric Company, whose main facility was in St Louis, Missouri, the company became independent as the Zinsmeyer Company following the onset of the Great Depression. The younger Zinsmeyer took over the company from his father in 1943 and renamed it Zinsco. The company was sold in 1973 to GTE-Sylvania, who continued to manufacture breakers and panels to the original Zinsco design for some years; this product line is now discontinued.

Aftermarket replacements for the Zinsco breakers are available; however, it may be more cost effective simply to replace the entire panel with a more modern and safer design from another manufacturer, depending on the number of breakers to be replaced. If the bus bar shows signs of corrosion, or if any of the breakers show signs of overheating, the panel should be replaced entirely. Many electricians advocate replacement of the panel in any case, due to its historically poor reliability.