The annual savings from selecting the high-efficiency motor, more efficient wire, and high efficiency transformer are 3,420 kWh ($307.80) in the motor, plus 626 kWh ($56.34) in the wire, plus 560 kWh ($50.40) in the transformer; totaling 4,606 kWh ($414.54). The total cost premium is $337.50. The payback period, using the total systems approach, is thus only ten months.
One point to remember is that selection of a more efficient downstream load device, like our motor example, or even the wiring size, affects the losses in the other components of the energy delivery system upstream. Since these additional savings tag along at no added cost, you should take credit for them in your calculations whenever there could be an objection to purchasing the more efficient systems.