The Siemens 3VA1125-6EF42-0AA0 is a SENTRON molded case circuit breaker (MCCB) rated for line protection, carrying a 25 A continuous current at 40 °C and a 4-pole configuration. Its TM240 thermal-magnetic overcurrent release handles overload and short-circuit protection without an undervoltage release or ground-fault monitoring.
Interrupting capacity and what it means for your panel
The interrupting rating hits 220 kA at 240 V, dropping to 154 kA at 415 V, 121 kA at 440 V, and 17 kA at 500 V or 690 V. That 220 kA figure at 240 V is the headline — it tells you this breaker can safely clear a fault up to that level on a 240 VAC line without rupturing or cascading upstream. For a 480 V panel the relevant number is the 121 kA at 440 V, which still covers most high-fault installations. The 17 kA at 690 V is the floor; if your service entrance sits at that voltage, verify the available fault current stays under that.
Thermal derating curve — the real continuous current
Rated 25 A from 40 °C through 50 °C (–), then steps down: 24 A at 55 °C and 60 °C, 23 A at 65 °C and 70 °C. That means in a warm enclosure — say 55 °C ambient — you lose 1 A of headroom. The maximum power loss is 8.5 W, which is modest for a 4-pole MCCB; it won't drive much internal heating beyond the ambient.
Physical fit and panel integration
Dimensions are 70 mm deep, 101.6 mm wide, 130 mm tall. The 101.6 mm width — exactly 4 inches — is the standard footprint for a 4-pole MCCB on a DIN rail or panel-mount base. The 70 mm depth leaves room behind a 200 mm deep enclosure door with clearance for wiring. IP40 on the front means tool-proof finger protection but no water ingress; keep it inside a rated enclosure.