What is the distance from which I can detect voltage?
It will depend on how high the voltage is and how much of an area is exposed and not covered by shields, which are grounded. The higher the voltage, the larger is the distance from which it is detected. A “hot” 7500 V overhead distribution line can be picked up from 200 feet (60m) away. A car in contact with 120 VAC is detected from about 8 feet (2.50m).