What this MCB rating means for your panel
The Siemens 5SY4406-7CV is a 4-pole miniature circuit breaker with a C6 tripping characteristic and a rated ultimate short-circuit breaking capacity (Icu) of 15 kA at 400 V AC. The 15 kA Icu means this breaker can safely interrupt a fault current up to 15,000 amps without welding its contacts or rupturing the case — critical for installations where the prospective short-circuit current at the panel is high. The C6 curve (6 A rated current, magnetic trip between 5 and 10 times In) suits it for protecting general-purpose circuits with moderate inrush, such as lighting banks, control transformers, or small motor starters.