Square D QOB390 is a three‑pole molded‑case circuit breaker rated for 90 A at 240 V AC, part of the QOB series and designed for bolt‑on installation in compatible Square D load centers. It provides thermal‑magnetic overcurrent protection with a 10 kA interrupting capacity at 240 V and is specified for 120/240 VAC operation in North American electrical systems. This 3‑pole device is intended for three‑phase distribution, offering secure panel integration and reliable protection for circuits up to 90 A.
