What this RCCB is and what the ratings mean for fit
The Siemens SENTRON 5SM3354-6 is a 4-pole residual current circuit breaker (RCCB) with Type A fault current detection, rated 40 A at 40 °C and 45 °C, and 500 V AC supply voltage. Type A means it detects sinusoidal AC residual currents plus pulsating DC residual currents up to 6 mA — the standard choice for circuits with single-phase rectifiers, switched-mode power supplies, or electronic loads that generate pulsed DC fault currents. The 10 kA short-circuit current rating (SCCR) tells you this device can safely interrupt a fault up to that level without upstream damage, which is the typical requirement for distribution boards fed by a transformer of that capacity. The 0.8 kA rating per EN 60898 and IEC 61008-1 is the conditional short-circuit capacity with the specified backup fuse — a lower number that governs coordination with the upstream protective device. Mounts on DIN rail (REG), occupies 4 width units (36 mm wide), and fits a 70 mm installation depth — standard for a 4-pole RCCB in a SENTRON distribution board. The IP20 rating applies only when the distribution board is installed with connected conductors; this is normal for panel-mounted devices and means no special ingress protection is needed inside the enclosure.
Thermal derating and operating range
The 40 A rating holds at 40 °C and 45 °C ambient. Above that, derate linearly: 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. If your panel ambient runs above 45 °C, size the upstream breaker or load accordingly — the RCCB itself will carry the derated current without nuisance tripping. Operating ambient range is -25 °C to 45 °C; storage range is -40 °C to 75 °C. The wider storage range means the part can sit in a cold warehouse or hot truck without damage, but the operating limit governs in-service use.
Panel integration notes
Mounting position is any orientation, which simplifies layout in crowded enclosures. Supply connection can enter from top or bottom — no mandatory feed direction. The device is finger and back-of-hand safe per the protection-against-electrical-shock spec, so live terminals are shielded during maintenance. Silicon-free construction (marked yes) matters for automotive or paint-shop environments where silicone outgassing can cause adhesion failures.