The 3VA1120-4EF32-0BC0 from the Siemens SENTRON family is a 3-pole molded case circuit breaker (MCCB) rated 20 A continuous at 40 °C ambient, with a thermal derating curve that holds 20 A up to 55 °C and drops to 19 A at 70 °C. Breaking capacity is the headline number for fault clearance: 121 kA at 240 VAC, 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at both 500 V and 690 V. At 240 V this breaker safely interrupts faults up to 121 kA without cascading upstream — it is sized for high-fault panels where a standard 25 kA or 65 kA MCCB would weld its contacts on a bolted fault.
70 mm depth (2.76 in), 76.2 mm width (3 in) per pole, 130 mm height (5.12 in). Rated insulation voltage 800 V. Maximum power loss 14.5 W.