The LV839115 is a MasterPact MTZ1 frame circuit breaker rated 800 A continuous at 40 °C, 3-pole, drawout mount, with LF breaking capacity. The 100 kA Icu at 480 V AC still covers most industrial distribution panels. The 10 kA short-time withstand (Icw) for 0.5 s per UL 489 governs selective coordination with downstream breakers: a downstream fault must clear before the MTZ1 trips, and this Icw rating tells you it holds closed through that delay. Drawout mounting means the breaker slides out of its cradle for inspection or replacement without disturbing line and load connections — essential for switchgear where uptime matters and you need to rack out a unit for maintenance while the bus stays live. The 2.8 in (70 mm) connection pitch matches standard drawout cassette spacing on MasterPact switchgear lineups. This unit ships without a Micrologic trip unit — the electronic trip system is ordered separately and plugs into the breaker face. That lets you select the exact trip curve (LSIG, LSI, etc.) and communication protocol (Modbus, Ethernet, IEC 61850) for your protection scheme without buying a fixed-trip breaker.
Because the trip unit is separate, verify that your protection engineer has selected the correct Micrologic model (e.g., 5.0, 6.0, 7.0) before ordering. The breaker frame and the trip unit are two line items on the BOM.
Deployment context
This breaker lives in a metal-enclosed low-voltage switchgear lineup — typically an ANSI-rated switchboard or a UL 1558 switchgear assembly. The drawout cradle bolts to the bus bars; the breaker rolls in on telescoping rails. The 10.9 in depth, 11.07 in width, and 12.7 in height are the cassette envelope, not the overall gear footprint — the enclosure depth is set by the bus and cable compartment behind the cradle. The 50/60 Hz network frequency covers both 50 Hz and 60 Hz installations without derating — common for global OEM panels that ship to both 50 Hz and 60 Hz sites.
Mechanical and electrical endurance
Rated for 10,000 mechanical cycles and 1,000 electrical cycles per ANSI C37.50. The electrical endurance figure governs how many times you can interrupt rated current before the arc chutes and contacts need inspection — relevant for motor-starting duty or frequent switching applications. The 9 ms maximum breaking time and 50 ms maximum closing response time are the breaker's intrinsic speed, independent of the trip unit.