What the breaking capacity ratings mean for your panel
The Siemens 3VA1125-6EF32-0KC0 is a SENTRON molded case circuit breaker (MCCB) rated 25 A continuous at 40–50 °C, with a 3-pole line-protection design. Its interrupting capacity climbs to 220 kA at 240 V, drops to 154 kA at 415 V, and holds at 121 kA at 440 V — then falls sharply to 17 kA at 500 V and 690 V. That 220 kA figure at 240 V means this breaker can safely clear a fault on a low-voltage distribution bus with very high available fault current, typical of transformer secondaries or large motor-control centers. The derating curve is tight: from 40 °C to 70 °C, current capacity only drops from 25 A to 23 A, so it holds rating across most panel ambient conditions.
Integration and auxiliary content
This MCCB ships with a factory-fitted shunt trip (STL) release and two HQ auxiliary switches — no field assembly needed for remote trip or status feedback. The 70 mm depth and 76.2 mm width fit standard Siemens 3VA panel-mounting footprints; the 130 mm height aligns with the 3VA1 frame. Rated insulation voltage is 800 V, so it can be applied on 480/277 V or 600 V systems with margin. Maximum power loss is 8.5 W, which matters for enclosure thermal calculations in sealed panels.