The pocket-sized voltage detector

The next generation VoltAlert™ AC non-contact voltage testers from Fluke
are easy to use – just touch the tip to a terminal strip, outlet, or supply
cord.
When the tip glows red and the unit beeps, you know there's voltage
present.
Electricians, maintenance, service, safety personnel, and homeowners can
quickly test for energized circuits in the workplace or at home.