The Siemens 5SY6504-8 is a SENTRON 5SY6-series miniature circuit breaker, 2-pole 1P+N configuration, D-curve, rated 4 A at 230 V AC. It carries a 30 kA breaking capacity under IEC 60947-2 and 6 kA under EN 60898 — the higher figure governs industrial panel coordination where fault current is substantial. The D characteristic means it tolerates inrush spikes up to 10–20× rated current, so it is sized for motor and transformer branch circuits, not lighting or general-purpose resistive loads.
For DC circuits the same standard gives 15 kA at up to 72 V. UL 1077 recognition at 5 kA covers North American supplementary-protection applications — same part, different passport, as we say in cross-border sourcing.
Sealable, touch-protected, IP20 with conductors connected.