What this 4-pole 8 A MCB does for a panel
The Siemens 5SY4608-5 is a 4-pole miniature circuit breaker from the SENTRON 5SY4 series, rated 8 A at 400 V AC with a tripping characteristic A. That characteristic A means it trips instantaneously at 2 to 3 times rated current — built for protecting semiconductor circuits or long cable runs where standard B or C curves would allow too much energy through before opening. The 4-pole (3P+N) configuration switches all three phases and the neutral, so it's the right fit for a three-phase subfeed where you want neutral protection and isolation in one unit. It snaps onto a DIN rail via the quick assembly system, occupies 4 width units (72 mm), and accepts solid or stranded conductors from 0.75 up to 35 mm² at both top and bottom combined terminals — enough cross-section for a 6 mm² feed and a 10 mm² loop-through if the panel layout needs it.
Breaking capacity — which standard governs your install
This breaker carries three interrupting ratings depending on the standard you're designing to: 10 kA per EN 60898 (the household / commercial standard), 20 kA per IEC 60947-2 (the industrial standard), and 5 kA per UL 1077 / CSA C22.2 No.235 for North American supplementary protection. That's enough headroom for most machine-level distribution boards fed from a transformer in the 100–200 kVA range.
Mounting and wiring — what the panel builder needs
Each terminal accepts solid or stranded copper from 0.75 mm² up to 35 mm², which covers everything from a 1.5 mm² control circuit to a 10 mm² feeder. The installation depth behind the panel is 70 mm (76 mm overall depth including the front of the housing). Sealable with a lead or wire seal if the application requires tamper-proofing. Ambient temperature range is -40 to +70 °C, with humidity derating above 55 °C — max 95% RH at 55 °C, dropping to 55% at 70 °C.