What this MCCB actually does on the line
The Siemens SENTRON 3VA1080-4ED42-0AC0 is a 4-pole molded case circuit breaker rated for 80 A continuous at 40 °C, with a TM210 thermal-magnetic trip unit designed for line protection — meaning it handles overloads and short-circuits in distribution panels, not motor starting. The 121 kA interrupting capacity at 240 V gives you headroom for high-fault installations where the available fault current is well above typical residential or light commercial levels. At 415 V it still breaks 75.6 kA, and at 690 V it holds 11.9 kA, so it's sized for industrial 400 V class systems where a transformer-fed bus can push serious fault energy.
Thermal derating and real-world current
The breaker carries its full 80 A up to 50 °C ambient. Above that it derates linearly: 78 A at 55 °C, 77 A at 60 °C, 75 A at 65 °C, and 74 A at 70 °C. If your panel runs hot — say a non-ventilated enclosure near a furnace line — you lose about 6 A off the top. That's not a showstopper, but it means the 80 A frame is really a 74 A breaker at the upper end of its rated operating range. The operating temperature range is -25 °C to 70 °C, storage from -40 °C to 80 °C.
Panel fit and auxiliary wiring
The 3VA1080-4ED42-0AC0 measures 101.6 mm wide, 130 mm tall, and 70 mm deep — a 4-pole frame that fits standard DIN-rail or screw-mount panel layouts. It ships with two HQ auxiliary switches built in, so you get status feedback without adding a separate accessory block. The insulation voltage is rated 800 V, which covers 690 V systems with margin. Maximum power loss is 19.2 W, so factor that into your enclosure thermal budget if you're stacking multiple breakers in a sealed cabinet.