What this MCCB is and what the ratings mean for fit
The Siemens SENTRON 3VA1020-3ED42-0AA0 is a 4-pole molded case circuit breaker (MCCB) rated 20 A at 40 °C, designed for line protection — meaning it protects cables and distribution buswork from overloads and short circuits, not motor or branch-circuit protection with different trip curves. The TM210 overcurrent release is a fixed thermal-magnetic type: the thermal element handles sustained overloads (inverse time), and the magnetic element clears short-circuit faults instantaneously. With a breaking capacity of 75.6 kA at 240 V AC, it can safely interrupt fault currents up to that level without cascading upstream — critical for high-fault installations like panelboards close to large transformers. At 415 V the interrupting rating drops to 52.5 kA, at 440 V to 32 kA, and at 500/690 V to 7.5 kA; the SCCR rating at the applied voltage is what governs the panel label. Rated current holds at 20 A from 40 °C through 55 °C ambient; at 60 °C it derates to 19 A, and it stays at 19 A through 70 °C. That flat derating curve means the breaker is not thermally starved inside a warm enclosure — a common gotcha with breakers that derate steeply above 40 °C. The insulation voltage is rated 800 V, so the breaker is electrically suitable for 480/277 V and 600 V panels with margin.
Panel integration and mounting
The 3VA1020-3ED42-0AA0 measures 130 mm high, 101.6 mm wide, and 70 mm deep. The 4-pole width is standard for a 4-pole MCCB in this frame size. Maximum power loss is 12 W — negligible for thermal budgeting inside a panel but worth noting if the enclosure is densely packed and naturally ventilated. Storage temperature range is -40 °C to 80 °C; operating range is -25 °C to 70 °C.