What the 125 A rating means for your panel
The Siemens SENTRON 3VA1112-3EF36-0AE0 is a 3-pole molded case circuit breaker rated 125 A continuously at 40 °C, 45 °C, and 50 °C without derating — meaning the full 125 A is available in a typical 40 °C panel environment. Above 55 °C the current tapers: 122 A at 55 °C, 120 A at 60 °C, 117 A at 65 °C, and 114 A at 70 °C. Breaking capacity reaches 75.6 kA at 240 V, 52.5 kA at 415 V, 32 kA at 440 V, and 11.9 kA at both 500 V and 690 V.
At 70 mm deep, 76.2 mm wide, and 130 mm tall, this MCCB fits standard 3-pole SENTRON panel cutouts and busbar systems. The 76.2 mm width (3 in) matches the common 3-pole MCCB footprint for 125 A class — no adapter plate needed for most Siemens switchboards or distribution boards.