What this MCCB delivers — and what the ratings mean for your panel
The Siemens 3VA1225-5FF42-0KH0 is a 4-pole SENTRON molded case circuit breaker (MCCB) rated for a continuous current Iu of 250 A. That 250 A holds flat from 40 °C through 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 — so in a crowded panel running warm, you still have headroom down to 223 A before the thermal element starts to drift. The TM240 overcurrent release is a fixed thermal-magnetic unit, not electronic, meaning no auxiliary power draw and no programming; it trips on thermal overload and instantaneous magnetic short-circuit. The interrupting ratings are the main selection gate: 187 kA at 240 V, 121 kA at 415 V, 36 kA at 440 V, and 17 kA at 690 V. At 415 V, that 121 kA covers virtually any industrial service entrance or feeder without needing a current-limiting fuse upstream. The rated insulation voltage Ui is 800 V, so it's comfortable on 480 V and 600 V class systems with margin.
Built-in auxiliaries and release — one less thing to add
This variant ships with a factory-fitted auxiliary contact block: 2 auxiliary switches plus 1 trip alarm switch (HQ designation). That covers status feedback and remote trip indication without a separate add-on module. The shunt trip release (STL) is also integrated, so you can trigger a remote trip from a safety circuit or E-stop string. The auxiliary trip module is order code 3VA9688-0BL33. No undervoltage release, no communication module, no ground-fault monitoring on this version — it's a straightforward line-protection MCCB for feeder or main breaker duty. IP40 on the front face keeps dust out of the mechanism in a standard enclosure.
Physical fit — dimensions that matter for panel layout
Width 140 mm, height 158 mm, depth 70 mm. That 70 mm depth is shallow enough for most 200 mm deep enclosures with the door closed. The 140 mm width is the 4-pole frame; a 3-pole sibling in the same 250 A frame is narrower, but this one needs the extra pole space for the switched neutral. Mounting is via the standard 3VA base plate or DIN rail adapter — check the Siemens mounting kit for your enclosure backplate pattern.
How it compares to the smaller-frame 3VA1110-5EE32-0JA0
If you're looking at the 3VA1110-5EE32-0JA0 as a potential second-source or substitution, the key difference is frame size and current. The 3VA1110 is a 100 A, 3-pole MCCB on a smaller physical frame. The 3VA1225-5FF42-0KH0 is 250 A, 4-pole, and physically larger — it will not drop into a panel cutout or busbar arrangement drilled for the 100 A frame without rework. The interrupting ratings also differ: the 100 A frame typically carries lower SCCR values. If your BOM calls for 250 A feeder protection with a switched neutral, this is the correct frame; the 3VA1110 is for downstream subfeeds or smaller loads.