SENTRON 3VA1112-4EF32-0BC0 — 125 A MCCB for Line Protection
The Siemens SENTRON 3VA1112-4EF32-0BC0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection duty, carrying 125 A continuously at 40 °C ambient. Its interrupting capacity hits 121 kA at 240 V AC and 75.6 kA at 415 V AC — numbers that matter when you're coordinating downstream fault levels in a distribution panel. The rated insulation voltage is 800 V, so it comfortably covers 480 V and 600 V class systems without derating the dielectric gap. This is a current-production part (lifecycle stage: current) with an undervoltage release (UVR) fitted and two auxiliary switches HQ as standard. No communication module, no ground-fault monitoring — it's a straight line-protection breaker with the UVR for load shedding or emergency stop integration. The power loss at full load runs 30.6 W, so factor that into your enclosure thermal budget if you're packing several in a row.
Breaking Capacity and Thermal Derating — What the Numbers Mean for Your Panel
The 121 kA at 240 V is the high-fault ace — it lets you place this breaker near a transformer secondary without worrying about series rating gaps. At 415 V it still holds 75.6 kA, and at 500 V it drops to 11.9 kA, which is the same figure at 690 V. That plateau tells you the arc extinction limit is reached above 500 V; for 690 V systems, you're coordination-limited to 11.9 kA available fault current. Thermal current holds flat at 125 A from 40 °C through 50 °C — no derating needed in a typical 40 °C panel. At 55 °C it drops to 122 A, at 60 °C to 120 A, and at 70 °C to 114 A. If your enclosure sits in a hot mezzanine or near a furnace line, that 114 A floor at 70 °C is the number to size against, not the 125 A nameplate.
Dimensions and Panel Fit
The breaker body measures 130 mm high, 76.2 mm wide, and 70 mm deep. That 70 mm depth is the key clearance number — it fits standard 100 mm deep enclosures with room for rear busbars or wiring channels. Width at 76.2 mm means three of these sit in a 230 mm wide section, leaving space for side cable entries. The 3VA1112-4EF32-0BC0 includes an undervoltage release and two auxiliary switches, so the depth stays within the same 70 mm envelope — no extra protrusion for the UVR module.