The LV839029 is a MasterPact MTZ3 frame drawout circuit breaker rated 4000 A continuous at 104 °F (40 °C) — that is the full-frame current, not a derated number, so it carries the main bus without a bump. The H3 breaking capacity delivers 100 kA Icu at 508 V AC per ANSI C37.50, meaning it safely interrupts a fault up to that level and recloses without service. For a 635 V AC system the Icu drops to 85 kA, still enough for most industrial secondary-distribution switchgear. The short-time withstand (Icw) is 85 kA for 0.5 s, which is the figure you use for selective coordination with downstream feeders — if your upstream breaker clears in under half a cycle, this frame holds closed and lets the downstream device isolate the fault. Integral instantaneous protection trips between 171 kA and 209 kA — that is the magnetic-only floor, not the adjustable pickup. The 25–30 ms maximum break time and 70 ms maximum closing response time are the mechanism's native speed; they govern arc-flash incident energy calculations for the IEEE 1584 study. Mechanical durability is 12,500 cycles, electrical durability 2,800 cycles per ANSI C37.50 — both are the mechanism's life before major overhaul, not the trip-unit life.
Drawout mounting and panel fit
This is a drawout chassis — the breaker cassette slides into a fixed cradle, so you can rack it out for maintenance without unbolting bus bars. The mounting support is base plate rails; the connection pitch is 9.06 in (230 mm) between phase centers, which is the standard MasterPact MTZ footprint. Panel cutout dimensions: width 40.5 in (1028.7 mm), height 18.8 in (478.1 mm), depth 16.8 in (426.8 mm). No Micrologic trip unit is included — you order the trip unit separately to match your protection curve (LSIG, LSI, or G).