In the Ontario Electricity Market large industrial users are subject to a Global Adjustment. In this, they are billed a substantial surcharge based on their power use in the top 5 hours of the May 1 – Apr 30 year (hours must occur on different days). Some mining operations have the ability to shed load rather easily, for instance by idling a rock crusher which can “catch up” with mine demand later. However, the decision to idle is complicated by the fact that it is not known, in advance, which the top five demand hours will be! I will present a combination of analytical and heuristic work designed to help make these decisions.