When did Zinsco panels stop being used?

Zinsco panels stopped being widely used in the late 1970s to early 1980s after the company encountered financial problems, safety concerns, and was eventually sold and discontinued. Zinsco, originally known as Zinsco Electrical Products, was founded in the 1940s and became popular in the 1950s through the 1970s for residential panels, particularly in the western United States including California, where many homes built in the 1960s and 1970s have Zinsco panels. In 1973, Zinsco was acquired by GTE Sylvania and became GTE Sylvania Zinsco, and production continued under that name for several years. By the late 1970s, reports of breaker failures and bus bar problems began to emerge, and the brand lost market share to competitors like Square D, Cutler-Hammer now Eaton, and Siemens. Production of Zinsco panels largely ended by the early 1980s, and the company went out of business, with remaining inventory sold off. The National Electrical Code and UL standards evolved, and Zinsco panels no longer met modern safety requirements, losing UL listing for many models. By the mid-1980s, Zinsco panels were no longer installed in new construction, though millions remained in existing homes, where they are now considered hazardous and recommended for replacement by electricians and home inspectors.