The LV839164 is a MasterPact MTZ2 drawout circuit breaker rated 1200 A continuous at 40 °C, 3-pole, with LF breaking capacity code. It carries UL 489 listings: 200 kA Icu at 240 V AC, 150 kA Icu at 480 V AC, and 100 kA Icu at 600 V AC — these are the fault-current levels it can safely interrupt without self-destruction, so the SCCR of the downstream panel must be coordinated against these values. The ArcBlok technology (integral instant protection set 49.5...55.5 kA) limits arc energy during a short-circuit event, reducing the pressure wave inside the enclosure.
Schneider Electric has marked the LV839164 as obsolete. If you are holding a panel design that specifies the MTZ2 drawout footprint, verify whether a current-production MasterPact MTZ frame (MTZ1, MTZ2, MTZ3) with equivalent ratings can be substituted; the drawout cradle and bus connections differ across frame sizes.
Drawout mounting on base-plate rails — the breaker slides into a fixed cradle with a 4.5 in (115 mm) connection pitch. The overall envelope is 17.5 in wide × 17.3 in tall × 16.8 in deep (444.3 × 438.8 × 426.8 mm). That depth includes the ArcBlok arc-chamber housing; verify the enclosure depth allows the full drawout racking travel before the breaker is committed to the panel layout.
Performance and durability
Mechanical durability is rated at 10,000 cycles per ANSI C37.50; electrical durability at 1,000 cycles under the same standard. Maximum breaking time is 9 ms, with a maximum closing response time of 70 ms. The short-time withstand current (Icw) is 22 kA for 0.5 s per UL 489 — this governs how long the breaker can carry fault current while waiting for a downstream device to clear, critical for selective coordination studies.