lightly cleaned all original early 20th century antique american industrial oversized three phase alternating current gantry crane switchboard designed and fabricated by the chicago switchboard mfg. co., chicago, il. the remarkably heavy antiquate electrical panel is comprised largely of a thick slab of black slate used for insulation purposes. the oversized three pole solid copper 600 amp trumball jacknife switch remains in great shape with original turned black enameled wood handle showing very little sign of wear and tear. the large flanking bussbars, designed to conduct substantial currents of electricity are fastened tightly against the back of the slate stone board. the three giant 600 amp (250 volt) fuses with knurled brass endcaps and copper blades were fabricated by the jefferson electric company, chicago, il. great overall condition, considering age. measures 36 x 9 x 28 1/4 inches.