What this 800 A MCCB delivers
The Siemens SENTRON 3VA2580-5HN32-0HA0 is a 3-pole molded case circuit breaker rated for 800 A continuous current at 40 °C through 60 °C, with a slight derating to 767 A at 65 °C and 703 A at 70 °C. It carries an ETU350 electronic trip unit offering adjustable long-time (Ir 0.5–800 A) and short-time (tsd 0.04–0.4 s) protection, plus an instantaneous pickup adjustable up to 8000 A (Ii). The interrupting ratings are 187 kA at 240 V, 121 kA at 415 V, and 53 kA at 690 V — meaning it can safely clear high-fault currents on the main feeder without cascading upstream. Front-side IP40 protection keeps dust and tools out of the trip-unit compartment in a clean panel environment.
Above 65 °C you lose about 4% per 5 °C step. The ETU350 electronic trip gives you adjustable long-time and short-time delays, so you can coordinate with downstream breakers without nuisance trips. Maximum power loss is 135 W — plan for heat dissipation in a dense panel.