Ul 1077 Mcb D Curve 2 Pole 20 Amp Breaker

Molded-case circuit breakers listed under ULT 489 are required to pass stringent short-circuit and switching test requirements. In all cases, interruption must occur successfully without the assistance of a backup device. In no instance are the contacts permitted to weld. Required electrical spacings and clearances are larger, and regular witnessed follow-up tests are mandatory.