The LV838917 is a MasterPact MTZ2 drawout circuit breaker — 3-pole, 800 A continuous rating at 40 °C, built for UL 489 applications up to 600 VAC. The LF breaking capacity code delivers 200 kA Icu at 240 VAC, 150 kA Icu at 480 VAC, and 100 kA Icu at 600 VAC. That spread covers most low-voltage distribution main and feeder roles in North American industrial switchgear. Drawout mounting means the breaker slides into a cassette — you can rack it out for maintenance or swap without disturbing the bus connections. The base plate rails and 4.5 in (115 mm) connection pitch match the standard MTZ2 switchgear lineup. Panel builders will recognize the footprint: 17.5 in wide × 17.3 in tall × 16.8 in deep.
At 480 VAC it still holds 150 kA Icu, and at 600 VAC it delivers 100 kA Icu. The short-time withstand (Icw) is 22 kA for 0.5 s under UL 489. That matters for selective coordination: downstream breakers can clear a fault while this breaker holds closed, keeping the rest of the bus live. The integral instantaneous protection trips between 49.5 and 55.5 kA, so it will not nuisance-trip on a moderate overload but clears hard faults fast. Maximum breaking time is 9 ms, closing response 70 ms — fast enough to limit arc-flash energy in most installations. The 800 A CT rating matches the continuous current rating; no need to re-spec the trip unit if you are replacing like-for-like.