Abstract: A portable unit, preferably adapted for plugging into a common wall outlet, has circuitry for monitoring the voltage and/or current provided through an electrical outlet. In addition to the monitoring circuitry, the unit preferably includes a microprocessor for digitally processing the power waveform as well as analytical quantities related to the waveform. Further, the unit preferably has a storage area for storing samples of the input waveform as well as a log of related analytical quantities for downloading to a computer, local area network, or other destination, for collection and analysis. Preferably, the unit is provided with a local visual display and an alarm indicator.