With this project measuring power in high voltage AC (500 Vrms max) or DC (300 V max) systems can safely be done, analog or digitally with class II isolation (>4 kV) thanks to high quality isolation amplifiers. Requires Elektor projects “Practical 4-channel ADC Module/ADS1115-BOB” 140169-91, “4-way filter” 140169-2, “Arduino Experimenting, Evaluation and Expansion Shield (Arduino EEE)” 140009 and an Arduino Uno.