Testing equipment can be put to good use ensuring that electrical equipment is properly installed and safe to operate. Faulty installations can be lethal; the condition of electrical installations can be established when contractors use test equipment. Gardner Bender is pleased to offer an innovative full feature line of test equipment designed to make electrical work faster and safer. The GVD-3504 tester from Gardner Bender indicates the presence of AC Voltage from 50 to 600 V with visual (flashing) and audible (beeping) indicators.