What this MCCB carries — and what it doesn't
The Siemens 3VA1225-4GF42-0HH0 is a 4-pole SENTRON molded case circuit breaker rated for 250 A continuous current (Iu) with a TM240 thermal-magnetic overcurrent release. It is configured for line protection — no ground-fault monitoring, no phase-failure detection, no communication module. The interrupting ratings are 121 kA at 240 V, 75.6 kA at 415 V, 25 kA at 440 V, and 11.9 kA at 690 V, so it handles high-fault utility feeds and large motor branch circuits where the available fault current is substantial. The auxiliary contact block is a 2+1 HQ configuration (two auxiliary switches plus one trip-alarm switch), and the integrated shunt trip (STL) release is order code 3VA9688-0BL30. The N-conductor protection is set to 100%, meaning the neutral pole is fully rated and switches with the phase poles — important for 4-wire systems where the neutral carries load current.
Thermal derating and panel fit
The 250 A rating holds flat from 40 °C through 50 °C ambient. Above that it derates: 243.3 A at 55 °C, 236.5 A at 60 °C, 229 A at 65 °C, and 223 A at 70 °C. If your panel ambient runs above 50 °C, size the upstream conductor and downstream bus for the derated value, not the nameplate 250 A. The operating temperature range is -25 °C to +70 °C; storage range is -40 °C to +80 °C. Dimensions are 140 mm wide × 158 mm high × 70 mm deep. The front face carries an IP40 protection rating — suitable for enclosed panel mounting, not for washdown or outdoor exposure. The trip indicator and voltage trigger are present, so you get local visual status and remote shunt-trip capability.