The Siemens SENTRON 3VA1225-4EF32-0CC0 is a 3-pole molded case circuit breaker (MCCB) rated for 250 A continuous current (Iu) with a TM240 thermal-magnetic overcurrent release. It's built for line protection in distribution panels, and its breaking capacity hits 121 kA at 240 V AC, 75.6 kA at 415 V AC, 25 kA at 440 V AC, and 11.9 kA at 690 V AC — so it handles high-fault utility feeds without cascading upstream. The unit includes an undervoltage release and two HQ auxiliary switches, and it's rated IP40 on the front, meaning it keeps dust out of the panel face but isn't meant for washdown environments.
What the ratings mean for fit
The 250 A rating holds steady from 40 °C up to 50 °C, then starts to derate: 243.3 A at 55 °C, 236.5 A at 60 °C, 229 A at 65 °C, and 223 A at 70 °C. So if your panel runs hot — say near a motor starter lineup or in a non-climate-controlled enclosure — you need to account for that thermal curve. The rated insulation voltage is 800 V, which covers most 480 V and 600 V systems with headroom. The 15 000-cycle latching endurance tells you it's rated for frequent switching, not just backup protection.
Integration and mounting
The breaker measures 105 mm wide, 158 mm tall, and 70 mm deep — a standard MCCB footprint for 250 A class. It mounts on a DIN rail or directly to a backplate via screw terminals. The IP40 front rating means it's fine for enclosed panels; keep it out of direct spray. The undervoltage release (UVR) and two HQ auxiliary contacts are built in, so you don't need to add separate accessories for remote status or trip indication.