Square D QOB3401021 Three-Phase Circuit Breaker

Square D QOB3401021 is a three‑pole, 40 A miniature circuit breaker from the QOB bolt‑on family. Rated for 120/240 VAC, it provides thermal‑magnetic overcurrent protection with a 10 kA interrupting rating at 240 VAC, making it suitable for protecting circuits in three‑phase distribution panels and load centers that accept QOB devices. This bolt‑on breaker includes a 120 V shunt‑trip coil for remote tripping in integrated safety or control applications. The 3P configuration means all three supply legs are switched simultaneously to protect three‑phase circuits, and its 40 A rating targets branch circuits with moderate current demand. When installed in compatible Square D QOB panelboards, it contributes to a coordinated distribution system that adheres to standard three‑phase wiring practice. The QOB3401021 is a genuine QOB series device and is designed to be replaced like‑for‑like in compatible equipment, ensuring consistent protection characteristics across the installation.