What this 4-pole D-curve MCB is for
The Siemens 5SY6408-8 is a 4-pole miniature circuit breaker from the SENTRON 5SY6 series, rated 8 A with a D tripping characteristic at 400 V AC. It breaks 6 kA under EN 60898 for standard household/commercial duty and 15 kA under IEC 60947-2 for industrial panel applications, so you can use it downstream of a transformer or in a sub-distribution board without worrying about fault current coordination. This is a current-production part — lifecycle stage marked current.
Width is 72 mm (4 width units on a DIN rail), depth 76 mm, height 90 mm, with an installation depth of 70 mm. IP20 with connected conductors; touch protection is built in. Sealable and halogen-free, silicon-free construction — relevant for food processing or clean-room panels where outgassing matters.
Breaking capacity and approvals
Three breaking-capacity ratings cover the main standards: 6 kA per EN 60898 (the residential/commercial standard), 15 kA per IEC 60947-2 (industrial), and 5 kA per UL 1077 / CSA C22.2 No.235 (North American supplementary protector). Overvoltage category III, rated impulse withstand for fixed installation. The DC rating maxes out at 72 V — fine for control circuits but not for high-voltage DC bus work.