Contact Voltage Detector detects the presence of voltages on structures which are supposedly voltage free such as light poles, fences, doors and literally any structure which can be contacted by an electric source. When held in the vicinity of a voltage potential, the instrument indicates the relative field strength of the surrounding electric field giving notification to the operator of its presence. A valuable tool for technicians who need to determine the safety of the enviornment or the validity of a true ground.
Contact voltage, also known as stray voltage, occurs when defective wires or cables energize objects such as manhole covers, lampposts, metal scaffolding or fencing or Wet conditions make it more likely for these objects to conduct electricity.
Then they can sweep it from side to side and up and down. As they get closer to the source of the electric field, more LEDs light up. Because the device is highly directional, more LEDs light up when the tip of the antenna is pointed directly at an energized object. They can then use a voltmeter to check the voltage on a particular object.