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Post: Hello Rhys The sample rate for the ADC Pi will be too slow for measuring AC voltages directly using the ACS712 or ZMPT101B. To measure a sinewave you need to sample at a rate at least 10 times faster than the frequency so for a 50Hz sinewave you would want to sample at 500Hz. The ADC Pi has a sample rate of 3.75 SPS at 18-bit or 240 SPS at 12-bit so you will not be able to get enough samples to make an accurate calculation of the RMS voltage. You also have the problem that the ADC Pi can only measure positive voltages so you would be unable to measure the negative half of the sinewave. Your best option with the ADC Pi would be to convert the AC signal to DC before measuring it. The LTC1966 should work for converting AC to DC but it has a maximum input voltage of 1V peak so you will have to make sure the voltage from your sensors does not exceed this. For measuring voltage you could use an isolation transformer to drop the voltage down but finding one with an output voltage of less than 1V will be difficult so you would need to use a voltage divider to drop the voltage to a safe level before passing it into the LTC1966. Using an Arduino would be another option. The ADC on an Arduino should have a fast enough sample rate to measure a 50Hz sine wave and you could do all of the RMS calculations inside the Arduino before sending the data to the Raspberry Pi through the UART, I2C or SPI bus. I found [url=https://docs.openenergymonitor.org/electricity-monitoring/voltage-sensing/measuring-voltage-with-an-acac-power-adapter.html]this article on the open energy monitor website[/url] which explains how to use an isolation transformer and resistors to measure an AC voltage on an Arduino.