The LV839142 is a MasterPact MTZ2 drawout air circuit breaker rated 2000 A at 40 °C, 3-pole, with H breaking capacity — 100 kA Icu at 480 V AC per UL 489 and 85 kA at 600 V AC. It ships without a Micrologic trip unit (ordered separately) but includes the ArcBlok arc-flash mitigation technology built into the interrupter. The drawout cradle and base-plate-rail mounting make this a switchgear-cell fit, not a panelboard drop-in.
Breaking capacity and short-time withstand — the decision numbers
The H code on this breaker means 100 kA Icu at 480 V AC and 85 kA at 600 V AC under UL 489. That 100 kA at 480 V is the interrupting rating the breaker can clear once and still be functional — it's not a withstand-then-trip figure. The short-time withstand rating (Icw) is 65 kA for 0.5 s per UL 489, which governs coordination with downstream breakers: if you need selective tripping with a 0.5 s delay window, this breaker will hold that fault current without opening first. The integral instantaneous protection range is 81–99 kA.
Durability and speed — what the cycle counts tell you
Mechanical endurance is 12,500 cycles per ANSI C37.50; electrical endurance under load is 2,800 cycles at rated current. The maximum breaking time is 25–30 ms from trip initiation to arc extinction, and the closing response time is 70 ms max. For a main breaker in a 2000 A switchboard that might see a handful of operations per year, those numbers are academic — but if this is an arc-flash reduction switch or a transfer breaker cycled weekly, the electrical endurance figure governs replacement interval.
Physical fit — drawout dimensions
The drawout chassis measures 17.5 in wide × 17.3 in high × 16.8 in deep (444.3 × 438.8 × 426.8 mm). Connection pitch between phases is 4.5 in (115 mm). The mounting support is base plate rails — typical for a switchgear cell with rear-connected bus. Verify the cell depth clearance; the 16.8 in depth is the breaker alone, not including the cradle rear studs or the arc-chamber exhaust path.