The Siemens 5SL6303-7CC is a SENTRON 5SL-series miniature circuit breaker — three-pole, C-curve, rated 3 A at 30 °C, with a 6 kA interrupting capacity tested per EN 60898.
Rated 3 A at 30 °C, but the thermal derating is real: at 40 °C it's 2.83 A, at 45 °C it's 2.74 A, at 50 °C it's 2.65 A, and at 55 °C it's 2.55 A. If the panel ambient runs warm, size up or accept the lower continuous current.
Sealable, halogen-free, silicon-free, and touch-protected. Pollution degree 2, overvoltage category III. No neutral conductor switching — this is a three-pole breaker for ungrounded phases only.