What this 4-pole 125 A MCCB brings to the panel
The Siemens SENTRON 3VA1112-4GF42-0AA0 is a 4-pole molded case circuit breaker rated 125 A continuous (Iu) with a TM240 thermal-magnetic trip unit. It's built for line protection in distribution panels where you need solid interrupting capacity: 121 kA at 240 V, 75.6 kA at 415 V, and still 11.9 kA at 690 V. The 800 V rated insulation voltage (Ui) gives headroom for 480 V or 600 V systems without derating the insulation. The thermal-magnetic TM240 release handles overloads and short-circuits in one package — no electronic adjustments, which means fewer things to go wrong out in the field. Power loss maxes out at 28.1 W, so panel heat buildup is manageable even in a packed enclosure. IP40 on the front means it's protected against solid objects larger than 1 mm, but it's not sealed against water — keep it inside a cabinet, not out in the weather.
Sizing and derating for real-world conditions
The 125 A rating holds steady from 40 °C up to 50 °C. At 55 °C it derates to 122 A, at 60 °C to 120 A, at 65 °C to 117 A, and at 70 °C to 114 A. If your panel runs hot near the top of the cabinet, account for that drop — a 125 A breaker in a 65 °C ambient is really a 117 A device. Dimensions are 130 mm high, 101.6 mm wide, 70 mm deep. That 70 mm depth is shallow enough to fit in most standard distribution panels without bumping the door or cover. The 4-pole design with 100 % N-conductor protection means the neutral pole is fully rated and trips with the phase poles — no derating or special coordination needed for the neutral path.
Lifecycle and sourcing posture
For compliance documentation, the SENTRON 3VA series carries UL, IEC, CSA, and CE certifications per standard Siemens practice. Specific declaration files (RoHS, REACH) are available through the manufacturer's support portal.
How it compares to the 3VA1112-5EE32-0AA0
The 3VA1112-5EE32-0AA0 is a 3-pole version with an electronic trip unit, while this 4-pole unit uses a thermal-magnetic TM240 release. If your panel was wired for a 3-pole breaker with electronic adjustments, swapping to this one means losing the adjustable trip curve and adding a neutral pole that needs to be landed. Same frame size — the 70 mm depth and 101.6 mm width are identical — so it physically fits the same mounting footprint, but the wiring and protection philosophy are different.