The Siemens SENTRON 5SL3240-7MB is a 2-pole miniature circuit breaker rated 40 A at 400 V AC with a C tripping characteristic and a 4.5 kA breaking capacity per EN 60898. The 2-pole design switches both phase and neutral (or two phases) in a single 36 mm wide unit, occupying 2 modular width units on the DIN rail.
The 76 mm depth and 70 mm installation depth fit standard distribution boards; the 36 mm width (2 modular units) means it occupies two adjacent 18 mm slots. IP20 with connected conductors is typical for enclosed panel use — no special sealing needed.
Rated for ambient temperatures from -40 °C to 75 °C, with the 40 A rating valid at 30 °C and 40 °C (derate above that per the thermal curve). The 10 000 mechanical switching cycles cover typical service life for a panel MCB. The part carries the EN 60898 rating (4.5 kA) and is designed for residential and infrastructure applications per the manufacturer's suitability listing.