A method of monitoring power usage of a load includes defining one or more parameters of the load that vary with a mode of operation of the load, receiving measurement data related to the one or more parameters of the load over a first period of time, recording the measurement data, determining a plurality of groups, each group defining a set of measurements in a continuous range of values, each group having a lower threshold value and an upper threshold value, the lower and upper threshold values defined by having less than a minimum threshold number of recorded measurements of the lower and upper threshold values, and associating a mode of operation with each of the plurality of groups.