Square D FAB14040B Molded Case Circuit Breaker

Square D FAB14040B Molded Case Circuit Breaker is a 40-amp, 1-pole thermal-magnetic MCCB designed for I-Line plug-in panelboard installations, providing reliable overcurrent protection for single-phase circuits in commercial and industrial electrical distributions. As part of the FAB family, the FAB14040B shares Square D's I-Line mounting design and is built for fast, safe installation in panelboards, with a thermal-magnetic trip mechanism that disconnects on overload or short-circuit conditions. Voltage configurations for related models in this family include 277V single-phase and 480Y/277VAC; the 1P 40A FY14040B is specified at 277V, while the FA14040B variant is rated at 480Y/277VAC, indicating multiple voltage configurations are available. Ambient operating temperature is 40°C for these breakers, and interrupting ratings for similar 1P, 40A models reach up to 18kA at 480Y/277VAC (and up to 25kA at 120/240VAC), reflecting the robust short-circuit protection typical of Square D MCCBs.