Siemens 3VA1225-4EF42-0BC0 — 250 A SENTRON MCCB for Line Protection
The Siemens 3VA1225-4EF42-0BC0 is a 4-pole SENTRON molded case circuit breaker (MCCB) rated for 250 A continuous current at 40 °C, with a maximum interrupting capacity of 121 kA at 240 V. It is designed for line protection — meaning it sits at the incoming feeder or main distribution point, not downstream branch protection — and includes an undervoltage release (UVR) as standard. The 250 A rating holds flat through 50 °C, then derates to 223 A at 70 °C, which is the maximum operating temperature.
Interrupting Capacity and Selectivity Planning
The interrupting capacity varies by line voltage: 121 kA at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, 17 kA at 500 V, and 11.9 kA at 690 V. For a 400 V panel, the 75.6 kA rating gives substantial SCCR headroom above typical 25–65 kA available fault currents, making this breaker suitable for high-fault installations like industrial substations or large motor control centers. The 800 V rated insulation voltage (Ui) confirms it can be applied on 690 V systems without additional series protection.
Physical Fit and Panel Integration
Dimensions are 158 mm height, 140 mm width, and 70 mm depth. The 70 mm depth is shallow enough for standard 200 mm deep enclosures, leaving room for wiring gutters and busbar connections behind the breaker. The 140 mm width is the 4-pole footprint — plan for a 4-module wide cutout if mounting on a DIN rail adapter plate. The breaker ships with an undervoltage release (UVR) and two auxiliary switches (HQ design), so factor those into wiring and terminal planning.