Dupro Tester

A Dupro tester - the pen-shaped voltage tester screwdriver carried in the top pocket of half the electricians in the country. Touch the tip to a terminal or conductor while a finger rests on the cap contact, and the lamp in the barrel lights if the point is live. It is the quickest possible answer to the question that matters most before touching anything: is this circuit dead. The body doubles as a small screwdriver for terminal screws, which is why it lives in a pocket rather than a toolbox. Used for checking sockets, switches, lamp holders, consumer units and terminations. It indicates presence of voltage only, not absence with certainty - for proving dead before working, use a proper two-pole tester.