Adjustable busway end box

An improved busway end box construction of the present invention terminates a busway run and provides insulation between the phase bars and the ground bar. The assembly includes an adjustable-height enclosure and an insulation sub-assembly. Adjustment slot in the top cover of the enclosure allows the top cover of the end box enclosure to slidably move up or down, varying the height of the busway end box. The insulator sub-assembly includes insulating walls nesting in between U-shaped comb-like brackets. Notches in the insulating walls provide vertical height to the insulator walls, allowing the insulator sub-assembly height to be self-adjusted as the height of the busway end box varies.