The Schneider Electric LV839312 is a MasterPact MTZ3 drawout circuit breaker, 3-pole, rated 5000 A at 104 °F (40 °C), with an H3 breaking capacity code. It is designed for ANSI C37.50 applications and delivers 100 kA Icu at 508 V AC, 85 kA Icu at 635 V AC. The unit ships without a Micrologic trip unit and includes ArcBlok arc-flash mitigation technology. This is a protection device for large industrial and utility power distribution — sized for main or tie breaker duty in switchgear where continuous current demands hit 5000 A. The drawout cradle lets you rack the breaker out for maintenance without de-energizing the bus.
Breaking capacity and withstand — what the H3 rating means for your coordination study
The H3 breaking capacity code on this MTZ3 means it can interrupt 100 kA Icu at 254 V AC and 508 V AC, and 85 kA Icu at 635 V AC per ANSI C37.50. Rated short-time withstand current (Icw) is 85 kA for 0.5 s per ANSI C37.50. The integral instant protection range is 171 to 209 kA, meaning the magnetic trip element responds to bolted faults above that threshold within the breaker's 25 to 30 ms maximum breaking time. Rated breaking and making capacity is 170 kA — this is the breaker's ability to close onto and immediately interrupt a fault, a key parameter for generator paralleling and capacitor bank switching where closing into a charged circuit is possible.
Physical integration into switchgear
Drawout mount with base plate rails — the breaker chassis slides into a fixed cradle that bolts into the switchgear enclosure. Connection pitch is 9.06 in (230 mm) between phase centers, matching standard ANSI switchgear bus spacing. Overall dimensions: 31.07 in (789.1 mm) wide, 18.8 in (478.1 mm) high, 16.8 in (426.8 mm) deep. Verify the cell opening in your existing gear against these before ordering. The breaker operates on AC control power at 50/60 Hz. Mechanical durability is rated at 12,500 cycles, electrical durability at 2,800 cycles per ANSI C37.50 — the electrical figure governs for load-break applications; expect contact inspection at that interval.