This is the variant for a three-contactor vertical stack. It interlocks contactors in the LC1F and CR1F ranges: bottom position for LC1F115...LC1F150 or CR1F150 (3P/4P), middle for LC1F185...LC1F225 or CR1F185, and top for LC1F265...LC1F330 or CR1F265. The mounting orientation is three vertical units.
What the Mechanical Interlock Rating Means for Fit
Mechanical interlocking is a positive-break linkage between contactor armatures — it guarantees that when one contactor's main poles close, the other's cannot, even if both coils are energized simultaneously. This is distinct from electrical interlocking (which depends on auxiliary contacts and can fail if a coil circuit welds). For reversing starters, dual-speed motor circuits, or generator-transfer schemes where simultaneous closure would create a phase-to-phase fault, the mechanical bar is the safety backstop. The three-vertical configuration means the interlock bar spans three contactors stacked in a column. The contactor frame sizes covered (LC1F115 through LC1F330) span a substantial current range — from 115 A up to 330 A in AC-3 duty — so this accessory fits across a wide motor-horsepower band on a 400 V or 480 V line.