Zinsco Panel

Also known as: ZinscoZinsco-Sylvania

Zinsco was a Los Angeles-based panel manufacturer whose residential load centers were installed widely across the Western U.S. from the 1950s through the early 1980s. Like Federal Pacific (FPE), Zinsco was later identified as having significant reliability problems — but with a different mechanism. Zinsco's aluminum bus bar alloy is highly susceptible to oxidation; oxidation creates resistance, resistance creates heat, and the cycle can end with the breaker's clip physically welding to the bus. A welded breaker can't trip during an overload — and its handle can read OFF while the fused connection still conducts (the "false off" hazard).

Zinsco was acquired by GTE-Sylvania in 1973, which continued producing the same design under the Sylvania name for several more years. If your 1970s panel says Sylvania, treat it as a Zinsco — same bus design, same problems, different label. All variants share the underlying design issues. See Sylvania panel for the branding note.

Zinsco panels have a documented, progressive failure mode, and we flag them whenever we see them — whether or not you called us about the panel. Replacement is a scheduled project, not something we do on the spot. Because of the false-off hazard, don't open a Zinsco panel yourself; photograph the closed panel and label and send it for a free read. Full story in the Zinsco panel replacement guide.