What the ratings mean for fit
The Siemens SENTRON 5SP4280-8 is a 2-pole miniature circuit breaker with a D tripping characteristic, rated 80 A at 30 °C and 400 V AC. The D-curve means it tolerates high inrush currents — typically used for motor, transformer, or lighting loads where the start-up surge would trip a B or C curve breaker. The 10 kA breaking capacity per EN 60898 certifies it can safely interrupt a fault current up to that level without damage, which is the standard for most commercial and light industrial distribution boards. Thermal derating is built into the spec: at 40 °C the continuous rating drops to 76 A, at 50 °C to 71.6 A, and at 60 °C to 67.2 A. If the panel ambient runs hot, size the upstream protection for the derated value, not the 30 °C headline number.
Mounting and integration
Snaps onto DIN rail or accepts screw fixing — both methods are listed. Occupies 3 modular width units (54 mm wide) on the rail. Depth is 76 mm; installation depth is 70 mm. Mounting position is unrestricted. Tunnel terminals at top and bottom accept conductors; touch protection is built in. IP20 with connected conductors, IP40 at the handle area with the distribution cover fitted.
Environmental and compliance
Halogen-free and silicon-free construction. Rated for pollution degree 3 (industrial environment) and overvoltage category III. Operating temperature range -40 °C to 75 °C. Shock resistance 150 m/s² at 11 ms half-sine per IEC 60068-2-27; vibration resistance 50 m/s² at 25 to 150 Hz and 60 m/s² at 35 Hz per IEC 60068-2-6.