The Siemens 5SY4108-7CV is a 1-pole miniature circuit breaker with a C tripping characteristic, rated 8 A at AC and a breaking capacity of 15 kA per IEC 60947-2. The 18 mm width (1 modular unit) and 76 mm depth fit standard DIN-rail enclosures. IP20 protection applies with conductors connected — the terminals are finger-safe only when wired; the front sealable cover allows a lockout tagout hasp for isolation verification.
Thermal derating and ambient limits
The 8 A rating holds at 35 °C ambient. At 40 °C it derates to 7.11 A, at 45 °C to 6.62 A, at 50 °C to 6.1 A, and at 55 °C to 5.53 A. The maximum ambient is 75 °C, minimum -40 °C, and the surrounding humidity limits are 95% RH up to 55 °C, 55% RH up to 70 °C, and 35% RH up to 75 °C.
Integration notes
The 5SY4108-7CV accepts combined terminals on both top and bottom, so busbar feed-through or daisy-chaining to adjacent breakers is straightforward. Neutral conductor switching is not provided — this is a 1-pole line-side only device. Rated for mechanical engineering and general industry use per the suitability field. Vibration resistance per IEC 60068-2-6: ±1 mm at 5–25 Hz, 50 m/s² at 25–150 Hz — adequate for machine-mounted enclosures on conveyors or pumps.