This unit is over rated. The Klein Tools NCVT-2 is way better. For starters, the plastic tip is too large and you either have to file it down or accept that it will wear down your outlets prematurely. Secondly, you can't hold it up to a light switch to test for voltage, so it is not that sensitive. Lastly, there's about a 250 ms delay before it detects voltage. I find this annoying. The Klein NCVT-2 has none of these issues and you can set it to a low-voltage mode to detect live switches. The 1AC-A1-II will serve as a door stop.