MasterPact MTZ2 fixed breaker — 1250 A, 66 kA, Category B
The LV848185 is a fixed-mount MasterPact MTZ2 circuit breaker from Schneider Electric, rated 1250 A at 40 °C with H1 performance level delivering 66 kA Ics across the full voltage range up to 690 V AC. Four poles, Category B selectivity — meaning it holds full rated short-time withstand (66 kA for 1 s) so downstream faults are cleared without tripping this main breaker, provided the coordination study respects the Icw envelope.
Selectivity and coordination — what the 66 kA Ics and Category B mean for the panel
Category B per IEC 60947-2 means this breaker is designed for selective coordination: it carries a rated short-time withstand current (Icw) of 66 kA for 0.5 s and 1 s, and 36 kA for 3 s. That Icw window lets downstream protective devices clear a fault before this main breaker trips — critical for a main or tie breaker in a switchboard where nuisance tripping takes the whole bus off-line.
Mounting and integration — fixed-mount, 4P, front/rear connections
Fixed-mount design, 537 mm wide × 352 mm high × 300 mm deep. Mounting support is rails or a base plate — the chassis bolts into the switchgear cubicle, not a DIN rail. Both upside and downside connections accept front or rear terminations, so the same breaker works in either cable-entry or busbar-drop configurations. Connection pitch is 115 mm, which matches standard MasterPact MTZ2 busbar riser spacing. Neutral is on the right side of the 4-pole assembly.
Environmental and endurance limits
Altitude derating applies above 2000 m — no derating needed up to 2000 m, above that consult the thermal curve. Electrical durability is 10,000 cycles at 440 V and 690 V AC per IEC 60947-2, with AC-3 motor-switching duty rated at 6000 cycles. Mechanical durability is 25,000 cycles with periodic preventive maintenance. Power dissipation at rated current is 100 W — factor that into the cubicle ventilation calculation if the breaker is in a sealed compartment with other heat sources.