What the ratings mean for fit
The Siemens 3VA1112-5EF36-0AA0 is a SENTRON molded case circuit breaker (MCCB) designed for line protection — meaning it protects cables and busbars from overloads and short circuits, not motor or generator windings. The TM240 overcurrent release is a thermal-magnetic trip unit: the thermal element handles sustained overloads with an inverse-time curve, while the magnetic element clears high-magnitude faults instantaneously. Rated 125 A at 40 °C, the breaker holds that full rating up through 50 °C ambient; above that it derates to 122 A at 55 °C, 120 A at 60 °C, 117 A at 65 °C, and 114 A at 70 °C. If your panel ambient runs above 50 °C, size the breaker for the derated value, not the nameplate 125 A. Short-circuit breaking capacity is voltage-dependent: 187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at both 500 V and 690 V. For a 480 V panel, the 75.6 kA at 440 V is the nearest published figure — expect similar or slightly lower at 480 V. The rated insulation voltage is 800 V, so the breaker is electrically rated for 690 V systems. Power loss at rated current is 28.1 W maximum; factor that into enclosure thermal calculations if you're packing multiple breakers in a small cabinet. Front protection is IP40 — finger-safe but not sealed against dust ingress. Mounts on a DIN rail or panel-mount base; the 76.2 mm width (3 inches) and 130 mm height (5.12 inches) are standard for this 3VA frame size. Operating temperature range is -25 °C to +70 °C; storage range is -40 °C to +80 °C.
Panel integration note
Three-pole design with no undervoltage release, no voltage trigger, no communication function, and no ground-fault monitoring. The trip indicator is absent — so there is no mechanical flag showing the breaker has tripped; you'll need to check the handle position or wire an auxiliary contact separately. If your panel requires a shunt trip or UVR for emergency-off circuits, this base variant does not include them; order the -5EF36-0AA0 suffix that corresponds to the TM240 release with no accessories. Verify the accessory slots on the 3VA frame accept field-installable shunt trips and auxiliary switches if needed later.