A tester screwdriver is a handheld tool that is used to determine whether electricity is flowing through circuitry. This type of tool may also be used to determine which wires in a system are hot, neutral, or grounded. The tip designed to detect electricity must be placed directly against exposed wire or metal to receive an accurate reading. It is shaped like a traditional flat head screwdriver so that it may also be used to adjust screws used in the repair process. It may be purchased through online ordering or from a local home improvement store.
This type of tool is long and cylindrical in shape, and tapers to a flat head. The handle is typically enclosed in plastic to protect the user from receiving an electrical shock while holding the tester screwdriver. The flat head is metal, and is the portion that should be placed against any electrical circuitry being examined. This type of head matches most screws frequently used to secure electric panels and face plates to hidden circuitry, and is convenient for general use during repair work.
The plastic handle of the tester screwdriver is often clear and contains a small, colored light inside. This light is illuminated when the screwdriver head is touched against a wire that is conducting electricity. The internal light source is frequently made from an LED bulb and may receive power from a small battery.
A tester screwdriver may also be used to check the polarity of electrical wiring. All electrical outlets using alternating current feature at least two prongs into which equipment may be plugged. One prong is connected to a hot wire, conducting the largest amount of electricity, and the other is connected to a neutral prong. Those which feature three prongs provide a third opening for grounding purposes. The screwdriver will light up when it is touched against the hot wire.
The metal head of the tester screwdriver should be placed directly against an exposed wire or bare metal during the examination process. If the head is touched to wire that is enclosed in a plastic sheath, it will automatically create a negative signal even though the wires may be conducting electricity. If exposed wires are in contact with bare metal, such as a screw that is holding several wires in place, then the head of the screwdriver may be placed against this metal, which will naturally conduct the current, to receive an accurate reading.