Receptacle testers are used to test wiring in electrical receptacles. They identify outlets that are open ground, open hot or open neutral; hot, hot on neutral, or ground reversed with open hot; and which have faulty wiring or reverse polarity. Receptacle testers can also be used to identify live circuits, determine the ground leg of a two-wire receptacle, and to check three-wire grounding outlets. Most products have a durable, ergonomic plastic case and several neon lamps which indicate the type of reading. Some products that are designed for three-wire, 125 VAC circuits can also be used to test ground fault circuit interrupters (GFCI) for proper operation. GFCI devices are protected circuit breakers that most building codes require in areas which contain water lines. GFCI de-energizes the circuit if an unsafe flow of current to ground is detected.
Receptacle testers are designed for use with specific receptacle types. There several basic types of electrical outlets, including 20-amp grounded, 15-amp grounded, and 15-amp ungrounded. Standard duplex receptacles have two outlets to receive plugs and a half-round grounding hole. The long slot is neutral and the short slot is hot. Unlike most 15-amp devices, 20-amp grounded receptacles have a T-shaped neutral slot. Receptacle testers are also used with specialized electrical outlets such as 20-amp, single-grounded; wall-mounted, 50-amp, 120 / 240 VAC; and floor-mounted, 30-amp, 120 / 240 VAC. GFCI receptacles are defined as specialized outlets, but are found in most residential, commercial, and industrial facilities. Receptacle testers for DC voltages (VDC) are also commonly available.
Receptacle testers are designed for use by industrial electricians and maintenance personnel who are responsible for testing and troubleshooting electrical equipment and electrical or electronic controls. Receptacle testers are designed to be plugged directly into an energized outlet, and usually feature a button which is pressed to overload the circuit. Most products are designed to test for ground fault interruption (GFI), open ground, open hot, open neutral, hot/ground reverse, and hot/neutral reverse conditions. Flashing or blinking colored lights indicates the circuit’s status or identify wiring errors. For example, a reading of open ground means that the receptacle has power but lacks a ground wire. Open hot and open neutral conditions characterize non-working electrical outlets.