The Siemens SENTRON 5SL3040-7 is a 1P+N miniature circuit breaker (MCB) rated at 40 A with a C tripping characteristic and a 4.5 kA breaking capacity at 230 V AC. The 1P+N configuration switches both the line and neutral conductors, with the neutral pole switching but not protected against overcurrent. That matters in single-phase residential or light commercial panels where you want a single-width unit that isolates both poles on fault. Rated 40 A continuous, this breaker handles the full load of a 9.2 kW resistive circuit at 230 V. If your fault current runs higher, you'll need a higher-rated device upstream for selectivity.
Snaps onto standard DIN rail, 18 mm wide (one width unit), 90 mm tall, and 76 mm deep. Installation depth is 70 mm. Tightening torque is 2 to 2.5 N·m (17.7 to 22.1 lbf·in) — standard for a screw terminal of this class. The unit is sealable (tamper-evident seal cap available), halogen-free and silicon-free construction, IP20 with conductors connected. That covers most indoor panel environments; derating applies above 45 °C per the thermal curve. The neutral conductor is switched — when the breaker trips or is manually switched off, the neutral pole opens too. This is a safety feature for single-phase circuits where you want full isolation. The unit also carries touch protection per the terminal design, and it's vibration-resistant per IEC 60068-2-6. Overvoltage category III, energy limiting class 3 — standard for distribution board duty.