RCCB for 400 V AC distribution boards
The Siemens SENTRON 5SM3342-6KK12 is a 4-pole residual current circuit breaker (RCCB) rated 25 A at 400 V AC, 50 Hz, designed for DIN-rail mounting in distribution boards. Rated 25 A continuous at ambient temperatures up to 45 °C, with derating above that: 23.5 A at 50 °C, 22 A at 55 °C, 20.5 A at 60 °C, 19 A at 65 °C, and 17.5 A at 70 °C. Instantaneous tripping (no intentional short-time delay), so it clears ground faults without waiting through a coordination window.
Height is 90 mm. That covers the full range from a 1.5 mm² lighting circuit tail up to a 25 mm² main feeder. Supply connects at the bottom per standard convention. Finger and back-of-hand safe per the shock-protection class, which is the expected touch-safe design for a DIN-rail component in a locked distribution board. Silicon-free construction, relevant for applications where silicone outgassing can contaminate contacts or optical surfaces — e.g., automotive paint shops or clean-room adjacent panels.