Voltage testers measure the flow of electric current passing through a circuit, battery, or outlet; it is an easy-to-use tool that no electrical engineer, hobbyist, or electrician should be without.

Voltage tester, tick-tracer, glow-tip, non-contact voltage tester... whatever. Same thing. I call it a voltage sniffer, but the technical name for this device is a capacitive voltage sensor. That's a ...