What this 250 A MCCB carries — and where the rating matters
The Siemens 3VA1225-5EF42-0BH0 is a SENTRON molded case circuit breaker (MCCB) rated 250 A at 40 °C, 4-pole, designed for line protection in distribution panels. The interrupting capacity is the headline number here: 187 kA at 240 V AC, 121 kA at 415 V, 75.6 kA at 440 V, 30 kA at 500 V, and 17 kA at 690 V. That means it can safely clear a fault up to those levels at the respective voltage — critical for high-fault-current installations like transformer secondaries or large motor control centers where upstream coordination demands a high SCCR.
Thermal derating and real-world current
The breaker holds 250 A continuously from 40 °C up to 50 °C. Above that it derates: 243 A at 55 °C, 237 A at 60 °C, 230 A at 65 °C, and 223 A at 70 °C. If your panel ambient runs hot — say a sealed enclosure near a furnace line — that 223 A at 70 °C is your real limit, not the nameplate 250 A. The operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C.
Built-in auxiliaries and releases
This variant ships with an undervoltage release (UVR) and a 2-auxiliary-switch + 1 trip-alarm-switch HQ configuration. The UVR means the breaker trips if control voltage drops — standard for safety circuits where loss of pilot power should open the main contacts. The auxiliary switches give remote status indication; the trip alarm switch signals a fault trip separately from a manual open. No communication function onboard — this is a hardwired breaker, not a smart metering unit.
Physical fit and panel integration
Dimensions are 158 mm high, 140 mm wide, 70 mm deep. That 70 mm depth is the body only — allow clearance for the handle throw and rear terminals. The 4-pole construction (22) means it occupies four module widths on the DIN rail or mounting plate. If you're swapping from a 3VA1110 frame (100 A class), the 3VA1225 is physically larger; verify the mounting footprint and busbar spacing before committing the panel layout.
Power loss and thermal management
Maximum power loss is 59.5 W at rated current. That's heat that stays inside the enclosure — factor it into your panel cooling calculation, especially if the breaker is grouped with other high-current devices. Insulation voltage is rated 800 V, so the internal clearances are designed for 690 V systems with margin.