Review on Klein Tools NCVT-2 Voltage Tester: Reliable Non-Contact Dual Range Tester with 3 m Drop Protection by Carlos Nolan

For the most part, this device is very easy to set up and understand, and will help you stay safe. To test if it works, test it in a working outlet, then unplug the circuit from that outlet in the box and test again. If you're actually using it on a refurbished outlet, check it out once before removing the cover etc. Then, with the cover removed, check the entire interior of the outlet again. You can have a loose (and live) wire if the people who built your house sucked like I did. Multiple sockets not associated with the code, including an outdoor flood socket that used the wrong wire gauge and configuration for one, but the correct gauge for the flood socket on the other. This tool will help you protect yourself from such jerks (you can't assume what's inside is correct and unpowered just because you cut power at the outlet). The only complaint I have is that this thing chirps a little once or twice when the box is off. I'm not sure if he picked up static electricity or anything, but if you're in doubt, just run a "prong" over the area 2 or 3 times and you should be able to spot it, before you start. You will not get multiple false positives. So if this happens, something is wrong / do not proceed. You may have to bite the bullet and consult a licensed electrician if the box is still giving you real-time current readings.