What it is and what it does
The Siemens SENTRON 5SY7408-7 is a 4-pole miniature circuit breaker with a C tripping characteristic, rated 8 A at 400 V AC. It interrupts faults up to 15 kA per EN 60898 and 30 kA per IEC 60947-2, so it handles both residential-grade and industrial fault currents without cascading upstream. The C-curve means it tolerates moderate inrush — typical for motor starters, pumps, and small transformers — without nuisance tripping, while still clearing overloads fast enough to protect the circuit.
Where it fits
Snaps onto DIN rail via the quick-assembly system, occupies 4 modular width units (72 mm wide), and mounts in any position. IP20 with connected conductors means it is meant for enclosed panels, not wet or outdoor locations. The 76 mm depth and 70 mm installation depth leave room for wiring in standard 80 mm deep enclosures. Combined terminals top and bottom accept both busbar and cable — no need to swap terminal types.
Compliance and approvals
Rated for overvoltage category III, pollution degree 3, and vibration resistance per IEC 60068-2-6. Halogen-free and silicon-free construction. UL 1077 and CSA C22.2 No. 235 listing at 5 kA extends its acceptance in North American panels.