Siemens 3VA4120-6ED24-1AA0 — 20 A SENTRON MCCB, 2-Pole, 100 kA IC
The Siemens 3VA4120-6ED24-1AA0 is a SENTRON molded-case circuit breaker (MCCB) rated for 20 A continuous at 40 °C, with a 2-pole configuration and a TM210 thermal-magnetic trip unit. It carries a 100 kA interrupting capacity at 240 V AC, stepping down to 65 kA at 480 V AC and 25 kA at 600 Y/347 V AC — numbers that tell you this breaker is built for high-fault panels where upstream coordination matters.
The 20 A rating holds flat from 40 °C to 55 °C, then derates to 19 A at 60–65 °C and 18 A at 70 °C. That thermal curve is the one you size against — if your panel ambient runs 60 °C, you're actually getting 19 A of headroom, not 20. Interrupting ratings are given at multiple voltage points: 100 kA at 240 V, 65 kA at 480 V and at 480 Y/277 V, and 25 kA at 600 Y/347 V. That spread tells you the breaker's arc extinction is voltage-dependent — at higher line-to-line voltages the available fault current it can safely clear drops. Power loss is 5.6 W maximum, which is modest for a 20 A frame and won't drive cabinet cooling decisions.
The breaker measures 50.8 mm wide, 129.4 mm high, and 75.1 mm deep — a 2-inch wide footprint that fits standard 2-pole MCCB panel slots. Depth of 75.1 mm (2.96 in) means it clears most 4-inch deep enclosures without a sub-panel extension.