MasterPact MTZ2 12 H10 — 1250 A Fixed Circuit Breaker
The Schneider Electric LV846542 is a MasterPact MTZ2 3-pole fixed circuit breaker rated for 1250 A at 40 °C, with a 50 kA ultimate breaking capacity (Icu) at 1150 V AC. It belongs to the H10 performance class, meaning it delivers 50 kA at the full rated voltage — the figure that governs fault interruption in a 1150 V distribution panel. Category B selectivity per IEC 60947-2 allows this breaker to coordinate with downstream devices, so a fault on a branch clears without taking the main bus off-line. The short-time withstand (Icw) holds 50 kA for up to 3 seconds, which matters for selective coordination schemes where the breaker must ride through a delayed trip on the feeder. Making capacity (Icm) is 105 kA at 1150 V — the peak let-through the contacts must close into without welding. It ships without a control unit, so the buyer specifies the trip unit separately based on the protection profile needed (LSIG, LSI, or electronic). The frame accepts sensor ratings from 630 A through 1250 A, giving some flexibility if the downstream load changes.
Deployment and Integration
Mounts on rails or a base plate in a fixed position — no draw-out cradle. Dimensions are 422 mm wide by 352 mm high by 300 mm deep, with a 115 mm connection pitch. Altitude derating applies above 2000 m — no derating needed below that. Power dissipation is 100 W at rated current, which must be factored into the enclosure ventilation design.
Compliance documentation covers EN/IEC 60947-1, EN/IEC 60947-2, EN/IEC 60947-2 Annex H, and IEC 61557-12. No UL or CSA listing is stated in the evidence — verify with the local Schneider office if a UL 489 mark is required for the installation.