What this MCB is and where it fits
The Siemens SENTRON 5SY4116-6CC is a 1-pole miniature circuit breaker rated 16 A with a B tripping characteristic, breaking 10 kA per EN 60898. That B-curve means it trips between 3 and 5 times rated current — standard for residential and light commercial lighting or socket-outlet circuits where inrush is low. The 10 kA breaking capacity at 230/400 V AC covers most distribution board fault levels without needing an upstream current-limiting fuse. At 18 mm wide (one modular unit), it snaps onto a DIN rail via the quick-assembly system and mounts in any position. Depth is 76 mm, installation depth 70 mm — that extra 6 mm is the terminal clearance for the combined top and bottom terminals. IP20 with conductors connected, so it lives inside a closed panel, not on the wet side of the enclosure.
Thermal derating and environmental limits
Rated 16 A at 35 °C ambient, but that drops to 14.7 A at 40 °C, 14 A at 45 °C, and 13.26 A at 50 °C. At 55 °C it's down to 12.5 A. If your panel runs hot — say a packed enclosure near a furnace line — size the upstream protection for the derated figure, not the 35 °C nameplate. The breaker itself survives -40 °C to 75 °C ambient, but the carrying current is what governs the circuit. Humidity limits: 95% RH up to 55 °C, then 55% RH up to 70 °C, then 35% RH up to 75 °C. That's typical for a sealed distribution board — no condensation inside. Pollution degree 3 means it's rated for conductive pollution or dry non-conductive pollution that becomes conductive due to condensation, which is the standard for most industrial control panels.