Zinsco QB2430 2 Pole Molded Case Circuit Breaker

The Zinsco QB2430 is a 30-amp, 2-pole molded‑case circuit breaker designed for use in Zinsco and GTE Sylvania panelboards. It operates on 240 V and uses a thermal‑magnetic trip mechanism to provide protection against overloads and short circuits, with an interrupt rating of approximately 10 kAIC at 240 V. The bolt‑on QB24 series breaker offers a secure connection to the panel bus and is typically found in legacy installations; it is obsolete and no longer manufactured, with common replacements including the Square D QO230 2-Pole 30A, Siemens Q230 2-Pole 30A, and Connecticut Electric UBIZ0230 2-Pole 30A Zinsco replacement breakers. It is used in residential and light commercial 240 V circuits for equipment such as air conditioners, water heaters, and compressors, providing overcurrent and short‑circuit protection for 30A branch circuits.