What this 3VA1112-5EF36-0BC0 is and what it does
The Siemens 3VA1112-5EF36-0BC0 is a SENTRON molded case circuit breaker (MCCB) in the line protection version, meaning it's sized and coordinated for feeder and main distribution circuits rather than direct motor starting. Rated continuous current Iu is 125 A, and the TM240 thermal-magnetic overcurrent release handles the overload and short-circuit protection internally — no separate relay needed. The 3-pole body carries a rated insulation voltage Ui of 800 V, so it's comfortable on 400 V and 480 V distribution panels with headroom for transient spikes. Breaking capacity is the headline number here: 187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at 690 V. Those are the maximum fault currents the breaker can safely interrupt without welding contacts or rupturing the arc chamber. For a 125 A frame, 187 kA at 240 V is high — it's sized for installations with large upstream transformers or parallel utility feeds where the available fault current is severe. The 690 V figure (17 kA) tells you it can also serve 690 V industrial networks, though the fault capability drops as voltage rises. Thermal derating is published per ambient temperature: the breaker holds 125 A from 40 °C through 50 °C, then steps down to 120 A at 55 °C, 117.5 A at 60 °C, 115 A at 65 °C, and 112.5 A at 70 °C. If the panel ambient runs hot (say 55 °C in a non-ventilated enclosure), the continuous load must be capped at 120 A — the nameplate 125 A rating only applies up to 50 °C. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C.
Panel fit and integration
The 3VA1112-5EF36-0BC0 mounts on a DIN rail or can be screw-fixed to a backplate. Dimensions: 130 mm height, 76.2 mm width (standard 3-pole MCCB width for the 3VA frame), 70 mm depth. The IP40 rating on the front means it's protected against tools and wires larger than 1 mm — standard for enclosed distribution boards, but not for washdown or outdoor exposure without an outer cabinet. It ships with 2 auxiliary switches HQ (high-qualified) factory-fitted, and an undervoltage release (UVR) is integrated — the release design is the undervoltage type. The auxiliary trip is a separate order code 3VA9608-0BB11 if you need to add a shunt trip later. No communication module, no ground fault monitoring, no phase failure detection on this variant — it's a pure line-protection MCCB with undervoltage coil and aux contacts for status feedback to a PLC or annunciator. Latching endurance is rated at 15,000 cycles — that's the mechanical life for the switching mechanism. For a main breaker that sees infrequent operation (once a week for maintenance), that's decades; for a breaker used as a daily disconnect, it's still a long service life. The trip indicator is not present on this variant — you'd need a different order code if visual trip flag is required.
Lifecycle and sourcing reality
For a BOM line that needs this exact order code, the fit is confirmed by the ratings above: 125 A continuous, 3-pole, TM240 release, undervoltage release, 2 aux switches. The breaking capacity at your system voltage (187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 440 V, 17 kA at 690 V) must exceed the available fault current at the installation point — that's the main coordination check. The 70 mm depth and 76.2 mm width match the standard 3VA footprint, so it drops into existing panels without busbar or enclosure modifications.