Abstract: A panelboard/switchboard assembly for accommodating bolt-on modules, plug-in modules and lugs. The panelboard/switchboard includes vertical, edge forward bus bars having a plurality of openings formed therein. The edge forward alignment allows plug-in modules to be mounted to the bus bars. The openings in the bus bars receive bolts for mounting straps to the bus bars and for mounting lugs to the bus bars. The openings have a shape having at least one linear element and receive a bolt having an anti-rotation portion with a similar shape. The interference between the opening and the anti-rotation portion of the bolt prevents the straps, and the modules connected to the straps, from rotating.