What the dual breaking capacity means for your panel
The Siemens 5SY4402-7KK11 is a SENTRON miniature circuit breaker (MCB) carrying two official breaking-capacity ratings: 10 kA per EN 60898 and 35 kA per IEC 60947-2. The EN 60898 figure governs residential and light commercial installations where the prospective fault current is known to stay under 10 kA.
C-curve and thermal derating — real-world trip behaviour
Rated 2 A at 35 °C ambient, the C-curve (tripping characteristic class C) means magnetic release occurs between 5 and 10 times rated current — so between 10 A and 20 A for a fast short-circuit trip. Above 35 °C, the thermal element derates: 1.9 A at 40 °C, 1.85 A at 45 °C, 1.8 A at 50 °C, 1.75 A at 55 °C, and 1.7 A at 60 °C.