The present disclosure pertains to systems and methods for retrofitting data collection systems in an electrical power system. In one embodiment, a retrofit system includes a wireless current sensor. The wireless current sensor includes a current monitoring subsystem to generate a digitized representation of a current measurement of an alternating current signal in an electrical conductor, a power harvesting subsystem to harvest power from the electrical conductor, and a first wireless communication subsystem to transmit the digitized representation of the current measurement. An analog-to-digital converter includes at least one analog input in electrical communication with a voltage signal associated with the electrical conductor and a digital output to generate a digitized representation of the voltage signal. An intelligent electronic device in communication with a second wireless communication subsystem and the ADC may provide the digitized representations to a main processor.