The Siemens SENTRON 5SM1354-6 is a 4-pole residual current circuit breaker (RCCB) from the 5SM1 design, rated 40 A at 45 °C ambient with a 30 mA Type A instantaneous trip characteristic — meaning it detects sinusoidal AC fault currents plus pulsating DC fault currents up to 1 kHz, which covers most modern electronic loads like VFDs, switched-mode supplies, and LED drivers that generate pulsed DC leakage. The 4-pole construction (3 phases + neutral) suits it for three-phase TN or TT systems up to 500 V AC line-to-line. The 30 mA trip threshold is the standard for personal protection against indirect contact in dry locations (IEC 60364-4-41). The thermal derating curve is explicit: 40 A at 40 °C and 45 °C, then 38.4 A at 50 °C, 36.8 A at 55 °C, 35.2 A at 60 °C, 33.6 A at 65 °C, and 32 A at 70 °C — so if your panel ambient runs above 45 °C, you need to down-rate the continuous load accordingly.
Mounts on DIN rail (REG profile) in any position — no orientation restrictions. Occupies 4 width units (about 72 mm) with a 55 mm installation depth. Screw terminals accept solid or stranded copper from 1.5 to 25 mm²; tighten to 2.5–3 N·m. Finger and back-of-hand safe touch protection built in.