Schneider Electric's Square D QOB320 is a three-pole, bolt-on miniature circuit breaker rated at 20 A and 240 VAC, with a 10 kA interrupt rating, designed for bolt-on mounting in compatible QO/NQO panel installations. It uses a thermal-magnetic trip mechanism, accepts 14–8 AWG conductors, and measures about 2.91 in long, 2.25 in wide, and 3 in high, making it suitable for compact load centers. This 3P, 20A device protects three-phase circuits in residential and light commercial distributions within panels that accept QOB bolt-on breakers.
