TPI 40 AC Volt Tester (Low Voltage) - The TPI 40 is essential to anyone determining the presence or absence of electrical voltage between 24-90 VAC. Use the TPI 40 for checking lawn irrigation equipment, thermostat controls, vending machine changers, and other low voltage equipment.

Defective Grounds: Electrical equipment that has a metal enclosure and is improperly grounded or has a defective ground will always result is the Sensors tip emitting a steady red glow. If there is enough electrical field present on the metal enclosure, the result will be a steady red glow and an audible tone.