The MGP26500 is a 500 A, 2-pole PowerPact M circuit breaker with an electronic ET 1.0 trip unit. The 65 kA AIR at 240 V AC (UL 489) and 35 kA at 480 V AC tell you it can handle high-fault-current panels without cascading upstream — critical for a main or large feeder in a distribution board. The IEC 60947-2 Icu of 50 kA at 240 V and 35 kA at 380/415 V means the same breaker meets both North American and international specs, so it fits a global BOM without a variant swap. The 80 % continuous current rating means the breaker is listed to carry 400 A continuously in a panel — not the full 500 A — unless you account for the 100 % rating option. That 80 % figure is the default for most UL 489 molded-case breakers; if your load pulls the full 500 A steady, you need to check the continuous-current derating for your enclosure and ambient.
This is a unit-mount breaker with lug terminals on line and load. The lug range accepts 3 x AWG 3/0 up to 3 x 500 kcmil aluminium or copper — sized for the 500 A feed. Tightening torque is 50 N·m (442.5 lbf·in) for the main conductors. Strip length is 25 mm (1.0 in). The IP40 front panel protection means it's suited for enclosed distribution panels, not washdown environments. Two plug-in slots accept auxiliary switch OF modules; one slot for an alarm switch SD; one slot for a voltage release MN or MX. That gives you remote status and shunt-trip capability without drilling the panel. The green trip indicator on the front gives local visual confirmation of a fault trip.
Carries UL 489, CSA, NEMA, NOM-003-SCFI-2000, and IEC 60947-2 marks. CE marked. HACR rated for heating, air conditioning, and refrigeration applications.