The Siemens 5SN6402-8CP is a 4-pole miniature circuit breaker from the SENTRON 5SN family, rated at 400 V AC with a breaking capacity of 6 kA according to EN 60898 and 30 kA according to IEC 60947-2.
The 6 kA breaking capacity under EN 60898 covers standard domestic and commercial fault levels; the 30 kA rating under IEC 60947-2 means it can also handle higher prospective short-circuit currents typical in industrial panels, so it can be specified in both contexts without an upstream current-limiting device in many cases. Rated at 400 V AC, 50 Hz, with a maximum of 440 V AC in multi-phase or single-phase operation. The DC rated maximum is 72 V, so it is not intended for high-voltage DC circuits. Mechanical service life is 10,000 operating cycles typical, and power loss is 1.2 W per pole at rated current in hot operating state — useful for thermal calculations in a densely populated panel. Accepts solid conductors up to 35 mm², which is generous for a 4-pole MCB of this size — sufficient for incoming feeds up to 63 A or so depending on the tripping characteristic (not specified here).