The LV839152 is a Schneider Electric MasterPact MTZ2 drawout circuit breaker, rated 1200 A continuous at 40 °C in a 3-pole configuration. It carries a UL 489 listing with L breaking capacity and ArcBlok technology, delivering 200 kA Icu at 240 V AC, 150 kA Icu at 480 V AC, and 100 kA Icu at 600 V AC — so it handles high-fault utility feeds without cascading upstream gear.
The 1200 A frame with 200 kA interrupting at 240 V covers transformer secondaries and main service entrances where fault current runs high. Integral instantaneous protection set at 72...88 kA provides a fixed magnetic trip band for bolted faults, while the 30 kA short-time withstand (Icw) for 0.5 s supports selective coordination with downstream feeders — the breaker holds in during a downstream fault long enough for the branch device to clear. Mechanical durability at 12,500 cycles and electrical durability at 2,800 cycles per ANSI C37.50 tell you this is a main breaker meant for switching duty, not a daily-operating disconnect.