I'm thinking of building a THD measurement device for the AC mains line (110VAC). I have very little experience in power circuits and have no idea what the typical THD values for a regular house line could be. I can always go for up to 100% in the scale; but I don't think it will get even close to that in worst case real scenarios, so that will deteriorate the instrument's resolution. Any ideas of the typical range???
Also, can I sample the 60Hz fast enough with Arduino and get multiple samples for one cycle? How many sample do you think I can get per cycle using Arduino?