Siemens 5SN6401-8CP — 4-Pole Miniature Circuit Breaker
The Siemens 5SN6401-8CP is a 4-pole miniature circuit breaker from the SENTRON 5SN series, rated for 400 V AC at 50 Hz. It carries a breaking capacity of 6 kA per EN 60898 and 30 kA per IEC 60947-2 — the higher IEC figure is the one that governs industrial panel coordination when the upstream transformer can deliver that fault current.
The 30 kA rating under IEC 60947-2 is the industrial-grade figure — it tells you this MCB can interrupt a 30 kA prospective fault current without welding its contacts or failing catastrophically, which is the number a panel builder needs for the SCCR declaration on the nameplate. Rated for multi-phase and single-phase operation at 440 V AC maximum, with a DC-side rating of 72 V maximum. The 4-pole configuration (4 modular width units, 72 mm wide) means it switches all three phases plus neutral — or four line conductors in a split-phase arrangement — in a single DIN-rail footprint. Installation depth is 70 mm, overall depth 76 mm, height 90 mm. Terminal capacity accepts solid conductors up to 35 mm², which covers most panel feed-throughs up to the 40–63 A range typical for this frame size.
The 72 mm width (4 modular units) occupies four 18 mm positions. Allow 70 mm clearance behind the rail for the housing depth; the overall depth of 76 mm includes the front toggle. Terminal screws accept solid or stranded copper; torque to the value printed on the device side.