What this MCB is and what the ratings mean for fit
The Siemens SENTRON 5SL3250-7 is a 2-pole miniature circuit breaker rated 50 A at 400 V AC, with a C tripping characteristic and a 4.5 kA breaking capacity per EN 60898. That C-curve means it handles moderate inrush — typical for motor starters, lighting banks, and small transformers — without nuisance tripping, while still clearing overloads fast enough for branch-circuit protection. The 4.5 kA rating tells you this MCB is sized for residential or light commercial distribution boards where the prospective fault current at the panel stays under that threshold; if your site has a transformer feeding a bigger fault current, you need a higher-rated upstream breaker for selectivity.
Panel fit and wiring constraints
The 5SL3250-7 snaps onto standard 35 mm DIN rail and occupies 2 width units (36 mm). Installation depth is 70 mm; overall depth including terminals is 76 mm — that extra 6 mm matters when you're squeezing a distribution board into a shallow enclosure. Terminal torque spec is 2.5–3 N·m, and the terminals accept solid or stranded copper from 0.75 mm² up to 25 mm², so you can land a 6 mm² feeder or a 16 mm² submain without adapters. Mounting position is any; no derating needed for horizontal or inverted orientation.