Review on KAIWEETS Voltage Tester: Non-Contact And Contact Pen For 12V-300V NCV Testing, LCD Display, Live/Null Wire Detection, Buzzer Alarm, And Wire Breakpoint Finder - VT500 by Tommy Abreu

I was a little leery when I ordered this. A one probe voltage tester just sounds wrong. I have been building electronic equipment and wiring higher voltage for many years, up to 480 volt irrigation plants out on the farm. So I was a little surprised when I opened the box and found a tool that looks to be well made and actually does most of what they claim it will do. With one lead it really does tell which wire is the hot one on AC. It does estimate the voltage and if all you need is to know that the outlet is carrying around 120 volts then it will work for you. BUT the outlet I checked had 119.3 volts (within tolerance for a 120v circuit) according to my digital volt ohm meter and this unit said that it was only carrying 106 volts. The continuity checker really does work. However it is using your body as part of the circuit. When I was taking electronics many years ago one of the first things they taught us was the one-hand rule. Unless you needed both hands to hold the test leads, put your other hand in your pocket. This keeps you from completing the circuit through your body. Some of the old equipment did not use proper isolation from the line power and if the two wire plug was inverted you could have 120 volts on the chassis which should be ground or zero volts. SO I NEVER JUST GRAB A WIRE TO COMPLETE A TEST CIRCUIT. I would much rather fry a meter than myself if I tie into a hot lead by mistake. So the bottom line is that I would stay away from this type of meter as dangerous! And not accurate enough for real world testing. If you really need this kind of test equipment, spend two to three times as much on a quality meter that is safe and accurate.