Challenger Sylvania HQB243040 Molded Case Circuit Breaker

The HQB243040 is a 3-pole, 40 A bolt-on molded case circuit breaker designed for 240 V three-phase circuits in industrial and commercial electrical distribution systems. It is commonly installed in Zinsco bolt-on panelboards and switchgear to provide overcurrent protection for motors, machinery, and feeder circuits in legacy installations. Key specifications include a 3-pole configuration, 40 A rating, 240 VAC nominal voltage, and an interrupt rating of approximately 10 kAIC at 240 V, with a thermal-magnetic trip (long-time and instantaneous) for overload and short-circuit protection. The device mounts bolt-on and functions as a branch or feeder breaker within motor control centers and three-phase distribution setups. As part of the Zinsco HQB/QB series, this breaker is discontinued/obsolete but still encountered in existing installations. For retrofit or modernization, common replacements include Square D QOB340 3-Pole 40A Bolt-On Breaker and Schneider Electric Multi9 3-Pole 40A Breaker, which preserve similar ratings and form factors.