The operational availability of mining shovels is the focus of this work. The hypothesis is that energy quality is responsible for the frequent shut downs of the shovels. Previous engineering studies have highlighted a large presence of harmonics and reactive power in the mine loop electric system. A common solution proposed was to use a combination of active filters, larger mobile substations, shorter mining cables and equipment location constraints. The aim of this paper is to produce a precise diagnosis of the source and nature of the energy quality issues. Mine loop electric quality monitoring, system modeling, equipment technologies and shoveĺs histograms are considered. Results are measured against IEEE standards and shoveĺs voltage regulation susceptibility. With the diagnosis the goal was to produce a reliable cost effective solution. Different alternatives are crosschecked with this paper proposal. The solution presented provides energy quality well within shoveĺs susceptibility and improves energy efficiency. The lower energy consumption pays the investment required and is currently under construction.