The Siemens 5SY6108-8CC is a SENTRON miniature circuit breaker, 1-pole, with a D tripping characteristic rated 8 A at AC. Its 6 kA breaking capacity per EN 60898 covers most industrial branch-circuit fault levels; the UL 1077 listing at 5 kA extends its reach into North American panels. The D curve means it tolerates the high inrush of motor or transformer loads without nuisance tripping — sized for a 3-phase motor starting current that would trip a C-curve on the same 8 A frame.
Derating and ambient conditions
The 8 A rating holds at 35 °C; at 40 °C the breaker must be derated to 7.35 A, at 45 °C to 7 A, and at 55 °C to 6.25 A (–). If the panel ambient runs above 35 °C, the continuous load must be reduced accordingly — a detail that often gets missed when the breaker is selected purely on the nameplate current. The operating range spans -40 °C to 75 °C, and the device can be mounted in any position, which simplifies layout in crowded enclosures.
Mounting and integration
At 18 mm wide (one modular unit) and 76 mm deep, the 5SY6108-8CC snaps onto a standard DIN rail via the quick-assembly system. The IP20 rating with connected conductors is typical for enclosed panel use — not for wet or dusty environments. Combined top and bottom terminals allow daisy-chaining without extra busbars. Pollution degree 3 and overvoltage category III confirm it is rated for the industrial panel environment, not just residential.