What this MCCB delivers on the panel
The Siemens SENTRON 3VA1112-4EF36-0BA0 is a 3-pole molded case circuit breaker rated for 125 A continuous current (Iu) at up to 50 °C ambient, with a TM240 thermal-magnetic overcurrent release. It's built for line protection — meaning it sits at the feeder or main distribution point, not on a motor branch. The interrupting ratings are 121 kA at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at 690 V, so it handles high-fault utility feeds without cascading upstream. The 70 mm depth and 76.2 mm width fit standard Siemens 3VA panel footprints; the undervoltage release (UVR) is integrated, and the auxiliary trip accessory (3VA9608-0BB11) can be added for shunt-trip or remote-trip applications.
Thermal derating and real-world current capacity
The 125 A rating holds flat from 40 °C through 50 °C. Above that, it derates: 120 A at 55 °C, 117.5 A at 60 °C, 115 A at 65 °C, and 112.5 A at 70 °C. If your panel ambient runs above 50 °C, size the feeder for the derated value — the TM240 release won't trip early, but the breaker's thermal capacity is the limit. The rated insulation voltage (Ui) is 800 V, so it's fine on 480/277 V or 600 V systems with margin.
What's not on this breaker
No trip indicator, no voltage-trip function, no communication module, no phase-failure detection, no ground-fault monitoring, and no auxiliary contact built in. The undervoltage release is the only integrated auxiliary. If you need remote status or shunt-trip capability, the separate 3VA9608-0BB11 auxiliary trip must be ordered alongside. The front face carries IP40 protection — fine for a dry indoor panel, not for washdown areas.