An electric motor controller and methods of determining which input power line of a plurality of input power lines of a motor drive controller has been energized are provided. An electric motor controller configured to be coupled to an electric motor includes a plurality of power input lines configured to receive an alternating current (AC) input voltage from an AC power source, an energized line detection device configured to sense that a power input line has been energized by the AC power source, and configured to output an isolated signal, and a rectifier configured to convert the AC input voltage having a frequency to a direct current (DC) voltage. The controller also includes a computing device coupled downstream from the energized line detection device and configured to determine which input power line has been energized.