The Siemens SENTRON 5SY8505-8 is a 2-pole miniature circuit breaker (1P+N) with a D tripping characteristic, rated at 0.5 A for AC circuits at 50/60 Hz. For DC circuits the same standard rates it at 15 kA. Under UL 1077 and CSA C22.2 No. 235 it carries a 5 kA interrupting rating — enough for supplementary protection in North American panels where the upstream device already limits fault current.
Mounting position is unrestricted, so it fits in vertical or horizontal busbar arrangements. Combined terminals at both top and bottom accept copper conductors.
Temperature derating and environmental range
Rated 0.5 A at 45 °C ambient; derates to 0.48 A at 50 °C and 0.47 A at 55 °C. The operating range spans -40 °C to 75 °C, with humidity constraints of 95% RH up to 55 °C, 55% RH up to 70 °C, and 35% RH up to 75 °C.