The Siemens SENTRON 3VA1125-3EF42-0AA0 is a 4-pole molded case circuit breaker (MCCB) rated 25 A continuous at 40 °C, designed for line protection in distribution panels. It carries a TM240 thermal-magnetic overcurrent release — the '240' indicates the fixed thermal trip threshold at 25 A, with magnetic short-circuit pickup calibrated to 240 A (approximately 10x In). This is the standard release for general-purpose feeder and branch-circuit protection where adjustable trip isn't required. The interrupting ratings climb to 75.6 kA at 240 V and hold at 52.5 kA at 415 V, then taper to 11.9 kA at 690 V — strong numbers for a 25 A frame, giving good selectivity headroom in most LV distribution schemes.
Thermal derating and application context
This MCCB holds its full 25 A rating from 40 °C up through 50 °C — no derating needed in a warm panel. At 55 °C it drops to 24 A, and by 70 °C it's at 23 A. That's a shallow derating curve (roughly 8% loss from 40 °C to 70 °C), which means in a tightly packed enclosure with elevated ambient, you still get most of the rated capacity. The rated insulation voltage is 800 V, and the front face carries IP40 protection — fine for dry indoor panel mounting, not for washdown environments. The 4-pole configuration handles three-phase plus neutral switching, common in North American and European distribution where the neutral needs to be switched or solidly grounded.
At 70 mm deep, 101.6 mm wide, and 130 mm tall, this breaker fits standard Siemens 3VA panel footprints. No undervoltage release, no communication module, no ground-fault monitoring — it's a straight thermal-magnetic MCCB, no frills. Power loss is 8.5 W maximum at rated current, which is modest for a 4-pole 25 A frame. The storage temperature range (-40 °C to 80 °C) exceeds the operating range (-25 °C to 70 °C), so it can sit in an unheated warehouse without issue.