Zinsco was a manufacturer of electrical distribution panels and circuit breakers, founded by Emile Martin Zinsmeyer and his son Martin Emile Zinsmeyer in the early 1930s.
History Frank Adam Electric, a manufacturer of electrical panels and circuit breakers, was founded in 1891 as part of the Blacker and Adam Watch Company in St. Louis, Missouri. In 1928, a young sales manager named Emile Zinsmeyer took charge of Frank Adam Electric's western division in Los Angeles. In the latter part of the Great Depression, Emile negotiated to buy Frank Adam's west coast stock, forming Zinsmeyer Company. Frank Adam Electric would continue manufacturing panels and breakers through the 1950s, and they are now extremely rare. Located at 729 Turner Street in Los Angeles, the Zinsmeyer Company would soon undergo some changes. Zinsmeyer employed two of his sons, Wilford, who went by Bill, and Martin. In 1943, Martin bought the company from his father and renamed it Zinsco Electric. Almost immediately, Zinsco began development of new panel and circuit breaker designs, with patent applications dating back to 1946. The first Zinsco panels contained copper bus-bars and copper breaker clips. Original breakers were patented in 1950 and labeled “Magnatrip.” Five additional patents would be issued for subsequent designs. These early breakers employed copper bus-clips, which matched the copper bus-bars in these panels. Prior to World War II, the only permissible electrical conductors were copper, gold, and silver. A copper shortage during the war promoted code changes. Although aluminum was initially expensive to manufacture, advancements in the processing and production of aluminum wire made it available by 1942 and it was added to the National Electrical Code. In 1952, the Korean War would cause another major copper shortage in the U.S. Although some companies, such as FPE and Square-D, continued to use an all-copper design, other manufacturers switched to an aluminum alloy for bus bars and breakers. Zinsco would remain with copper in both their panels and breakers until the third major copper shortage in the early 1960s, when they would switch to an aluminum bus. In 1963, Zinsco introduced the R-38 twin breaker, which was the only twin circuit breaker that also made contact on both bus-bars for 240 volts in a single breaker space. This made the Zinsco brand hugely popular with contractors and millions of Zinsco service panels and load centers were installed through the 60s and 70s. In 1973, Martin Zinsmeyer sold the Zinsco Electric Company to GTE-Sylvania. During that ownership, the product line remained the same, with new labeling and branding, while dropping the “Magnatrip” label. In 1978, the line changed names again, and was re-labeled Challenger. By 1981, GTE-Sylvania divested itself of the electrical distribution business and sold off its product lines and manufacturing facilities. The Challenger line, mostly manufactured at the time in Jackson, Mississippi, was sold to a former officer of GTE, who used the Challenger name as the name of his new company, Challenger Electrical Equipment Corporation. The new Challenger Brand immediately ceased production of any new Zinsco frame panels and load-centers, but still produced the re-branded Zinsco circuit breaker line. Challenger concentrated on a new line of panel equipment using the same bus configuration proven with Murray, Crouse-Hinds, and others. But, from 1982 until 1994, the 200-amp service panels used a Zinsco frame main breaker. Challenger flourished through the 80s, and was eventually received by Westinghouse in a multi-asset deal, in order for Westinghouse to sell its remaining electrical manufacturing facilities to Eaton Corporation in 1994. Both Challenger and Thomas & Betts (T&B) had manufacturing facilities in Mississippi, where T&B received the Zinsco circuit breaker molds. T&B then continued to fabricate and sell the breakers under their own label, tripling the price at that time, from about $7.00 for the popular R-38 twin breaker to $19.00. T&B would eventually close the Zinsco circuit breaker production altogether in 2005. Today, Connecticut Electric continues making Zinsco replacement tin coated copper bus bar kits and breakers.
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