Trailing cable electric excavators have been around for fifty years at least.all the really big shovels and draglines are electric. Also the bucket wheel excavators in the Latrobe Valley. Electric wheel haultrucks, with diesel engines driving generators, were developed in the 1960s and widely used. Underground, we had trolley wire electric haul trucks from Kiruna at Mount Isa in the 1980s. The first trolley wire electric locomotives were used in Victorian gold mines and at Broken Hill South from 1902 onward.