What this MCCB carries and where it fits
The Siemens SENTRON 3VA1225-4EF42-0JH0 is a 4-pole molded case circuit breaker rated for line protection, with a continuous current of 250 A up to 50 °C and a short-circuit breaking capacity of 121 kA at 240 V — that's the figure that governs SCCR compliance in a 240 V panel. At 415 V it still holds 75.6 kA, dropping to 11.9 kA at 690 V. The 70 mm depth and 140 mm width fit the standard SENTRON 3VA footprint, so it drops into existing DIN-rail or mounting-plate layouts without re-drilling.
Thermal derating and auxiliary fit
Rated 250 A at 40 °C, 45 °C, and 50 °C — no derating needed in a standard 50 °C enclosure. Above that it steps down: 243 A at 55 °C, 237 A at 60 °C, 230 A at 65 °C, and 223 A at 70 °C. The 57 W maximum power loss matters for heat rise in a tightly packed panel; check your enclosure's dissipation budget if you're grouping several breakers. Comes with a shunt trip (STL) for remote tripping and two auxiliary switches plus one trip alarm switch (HQ) for status feedback to a PLC or annunciator.