Zinsco QB24-1030U Molded Case Circuit Breaker

The Zinsco QB24-1030U is a 30 Amp, single-pole molded case circuit breaker designed for use in Zinsco / GTE Sylvania panelboards, operating on 120V with a thermal-magnetic trip and an interrupt rating of approximately 10 kAIC. It uses bolt-on mounting in the QB series, securing a firm electrical connection to the panel bus in legacy installations. Commonly used in residential and light commercial electrical systems for 30A branch circuits such as air conditioning units, compressors, dedicated receptacles, and small equipment loads, this breaker is listed as Obsolete / discontinued. For older Zinsco bolt-on panels, common replacements include Square D QO130 1-Pole 30A Circuit Breaker, Siemens Q130, and Connecticut Electric UBIZ30.