125 A MCCB with 75.6 kA interrupting rating — line protection for main feeder panels
The Siemens 3VA1112-3EF36-0CC0 is a 3-pole SENTRON molded case circuit breaker rated 125 A at 40 °C, with a breaking capacity of 75.6 kA at 240 V AC. The interrupting rating drops to 52.5 kA at 415 V, 32 kA at 440 V, and 11.9 kA at 500/690 V — so the available fault current at the panel location determines which voltage column governs the selection. This is a line-protection design (not feeder or motor-protection), meaning the thermal-magnetic trip curve is shaped for cable and busbar protection rather than motor inrush.
Rated current holds flat at 125 A from 40 °C up to 50 °C, then derates to 122 A at 55 °C, 120 A at 60 °C, 117 A at 65 °C, and 114 A at 70 °C. The unit occupies a 76.2 mm (3 in) width on the DIN rail, with a depth of 70 mm and height of 130 mm — fits standard panel layouts for 125 A class MCCBs. Maximum power loss is 30.6 W, which contributes to the enclosure heat budget.