The highwall miner‟s energy consumption was monitored using a PowerLogic CM4250 circuit monitor (Square D, Palatine, IL). The unit is a multifunction, digital instrumentation, data acquisition and control device. The CM4250 was used in conjunction with a PowerLogic 3090 SCCT063 current transformer (CT). The meter has an accuracy of ±0.04% of reading plus 0.025% of full-scale current/voltage. The CT is rated at 1% accuracy.