The LV839144 is a MasterPact MTZ2 drawout circuit breaker rated 3000 A continuous at 40 °C, 3-pole, with an H breaking capacity code. That H code means it delivers 100 kA Icu at 480 V AC and 85 kA Icu at 600 V AC under UL 489 — which is the interrupting rating that governs whether this breaker clears a fault without blowing up upstream gear. The 65 kA Icw short-time withstand rating for 0.5 s (UL 489) tells you it can ride through a delayed trip coordination scheme, so you can build selective coordination downstream without losing the main. The drawout mounting means the breaker chassis stays bolted to the base plate rails while the mechanism slides in and out — no need to disconnect power cables for maintenance or swap-out. That's the kind of feature that keeps a line-down event under an hour instead of a shift. The integral instantaneous protection trips between 135 and 165 kA peak, and the maximum breaking time sits at 25 to 30 ms. That speed limits arc energy and lets the ArcBlok technology do its job — containing the arc inside the pole and reducing pressure buildup in the enclosure.
Where it sits in the panel
The drawout cradle mounts on base plate rails, with a 4.5 in (115 mm) connection pitch that matches standard bus-bar takeoff spacing. Physical footprint is 17.5 in wide by 17.3 in tall by 16.8 in deep — that's a substantial piece of iron, so plan the enclosure depth and bus-bar routing accordingly. The breaker ships without a Micrologic trip unit, so you'll select and install the appropriate electronic trip relay separately.