Tests standard receptacles and extension cords to ensure proper wiring. Neon indicators give positive indication of circuit status. Compact unit simply plugs into any standard 3-wire/grounded receptacle or extension cord (110 /125 volt circuits). Tests for six circuit conditions: open ground, open neutral, open hot, hot/ground reverse, hot/neutral reverse and correct wiring. Yellow and red lights provides indication of circuit status or specifies wiring errors.