What it is and what the ratings mean
The Siemens 5SL4414-7CC is a 4-pole miniature circuit breaker (MCB) rated at 400 V with a 10 kA breaking capacity, C-trip curve, and a 0.3 A current rating. The 10 kA breaking capacity means it can safely interrupt a fault current of up to 10,000 amps at 400 V without welding its contacts or causing an arc flash — enough for most commercial and light industrial distribution boards. The C-curve (trips between 5 and 10 times rated current) is the standard choice for moderate inrush loads like small motors, transformers, or lighting ballasts; it avoids nuisance tripping on startup while still protecting the circuit from sustained overloads. At 0.3 A, this is a very low-rated MCB — sized for control transformers, signal circuits, or instrumentation feeds where a standard 1 A or 2 A breaker would not provide adequate protection.
Where it fits and how it mounts
Snap-on DIN rail mounting for standard 35 mm rail (EN 60715). The 4-pole width is 72 mm (4 x 18 mm modular units). Spring-cage terminals accept 0.75–25 mm² conductors. Panel builders should account for the 0.3 A rating when sizing upstream protective devices — this breaker is the load-side device, not a main incomer. In a distribution board, it typically feeds a control transformer or a small power supply, not a direct motor load.