What this 4-pole MCB does in the panel
The Siemens 5SN6403-8CP is a 4-pole miniature circuit breaker from the SENTRON 5SN family, rated 400 V AC at 50 Hz with a C-trip curve. Four poles (3P+N) in a 4-module-width housing (72 mm wide, 90 mm tall, 76 mm deep) snap onto standard DIN rail, with 70 mm installation depth behind the panel door. Terminal capacity accepts solid conductors up to 35 mm², enough for most feeder and sub-feed circuits in a distribution board.
DC operation is limited to 72 V maximum — this is not a general-purpose DC breaker for photovoltaic strings or battery banks. On the AC side, multi-phase and single-phase operation both top out at 440 V, giving you a 40 V margin above the 400 V nominal for supply variations. If you need frequent on-off cycles, look at a contactor or switch-disconnector instead.
Panel integration and environmental range
Snap-on DIN rail mounting, 4 width units (72 mm). Ambient storage range spans -40 °C to 75 °C, so it can sit in an unheated warehouse or rooftop cabinet without issue; operating temperature is typically -25 °C to 55 °C for the 5SN family.