What this 3VA1225-6EF42-0HH0 brings to the panel
The Siemens 3VA1225-6EF42-0HH0 is a SENTRON molded case circuit breaker (MCCB) rated for 250 A continuous current with a TM240 thermal-magnetic trip unit — meaning it protects against both sustained overloads and short-circuit faults in one compact package. The 4-pole design handles three-phase plus neutral, and the line protection variant is the standard choice for feeder and distribution circuits where you need selective coordination downstream of a transformer or main switch. Breaking capacity is the headline number here: 220 kA at 240 V AC, 154 kA at 415 V, 36 kA at 440 V, and 17 kA at 690 V. Those figures mean this breaker can safely interrupt fault currents up to those magnitudes at the respective system voltages — critical when you're sizing for high-fault locations like a service entrance or a large motor control center where the available short-circuit current is substantial. The TM240 release is a fixed thermal-magnetic type — no electronic adjustment, no communication module, no ground-fault sensing built in. It's a workhorse for straightforward line protection where you don't need the configurability of an electronic trip. The auxiliary contact package (2 auxiliary switches + 1 trip alarm switch HQ) and the integrated shunt trip (STL) release give you remote status and tripping capability without adding external modules.
Thermal derating and installation context
The continuous current rating holds at 250 A up to 50 °C ambient, then derates to 243.3 A at 55 °C, 236.5 A at 60 °C, 229 A at 65 °C, and 223 A at 70 °C. If your panel runs hot — say inside a non-climate-controlled enclosure near a furnace line — you need to account for that drop. The operating temperature range is -25 °C to 70 °C, with storage from -40 °C to 80 °C. Dimensions are 140 mm wide, 158 mm high, and 70 mm deep. The front face carries an IP40 rating — fine for a closed panel, but not for washdown environments. The trip indicator and voltage trigger are present, so you get local visual status and a remote trip signal via the shunt release. This mounts on a DIN rail or directly to a backplate via the breaker's own mounting points. The 4-pole form factor takes up the same width as four single-pole breakers ganged together — plan your enclosure fill accordingly. No undervoltage release, no phase-failure detection, no communication function on this variant; it's a straight line-protection MCCB with the essentials.