What this MCCB carries and where it fits
The Siemens 3VA1020-3ED36-0DH0 is a SENTRON molded case circuit breaker (MCCB) rated for 20 A continuous at 40 °C ambient, with a 3-pole configuration for three-phase line protection. Its interrupting capacity hits 75.6 kA at 240 V AC — enough for high-fault service-entrance or distribution panels where the available fault current is substantial. The 800 V rated insulation voltage means it can sit in 480Y/277 V or 600 V systems without derating the dielectric.
Breaking capacity across voltage levels
The interrupting rating drops as voltage rises: 75.6 kA at 240 V, 52.5 kA at 415 V, 32 kA at 440 V, and 7.5 kA at both 500 V and 690 V (–). For a 480 V panel, the relevant figure is the 440 V rating (32 kA) — conservative to use that for 480Y/277 V systems. At 600 V class, the 7.5 kA at 690 V applies, which is low for high-fault industrial mains; this breaker is better suited to downstream subpanels or branch protection at those voltages.
Thermal derating and ambient limits
The breaker holds 20 A from 40 °C through 55 °C ambient (–), then derates to 19 A at 60–70 °C (–). That flat thermal curve is unusual — most MCCBs start derating above 40 °C. It means you can run this breaker near its full rating in a warm enclosure without recalculating. Operating ambient range is -25 °C to 70 °C (–); storage from -40 °C to 80 °C (–).