Rating and fit — what the numbers mean for your panel
The Siemens 3VA1225-6EF42-0BA0 is a SENTRON molded case circuit breaker rated 250 A continuous at 40 °C through 50 °C, then derating to 223 A at 70 °C. That thermal curve means the breaker holds full load at typical panel ambient; only above 55 °C does the TM240 trip unit start backing off. For a 4-pole line-protection device, the interrupting ratings span 220 kA at 240 V down to 17 kA at 690 V — so the SCCR headroom is there for high-fault commercial mains, but the 690 V tier is the one to check if you're feeding a 480 V or 600 V distribution bus.
Integration — panel fit and release options
The breaker measures 140 mm wide by 158 mm tall by 70 mm deep — a standard SENTRON 3VA frame footprint that drops into existing panel cutouts without re-drilling. It ships with an undervoltage release (UVR) as the auxiliary release type, so the coil drops out below a set threshold; verify the control voltage matches your safety circuit before landing the wires. The TM240 thermal-magnetic trip is fixed, not electronic — no communication function, no ground-fault monitoring version on this variant.