The 273 HP is a Non contact voltage detector. It has two ranges for selection.The 273 HP consists of an internal pickup sensor, a function selection switch, a visual and a sound annunciator. With the 273 HP, physical contact with electrical conductors is not necessary when testing for live lines. Its sensor senses the radiated field which surrounds live conductors. Radiated field strength increases with voltage and decreases quickly with distance or earth shielding Some of the typical applications are : non contact detection of live voltages; find faults in cables; check and detect live high voltage cables; trace live wires; check high frequency radiation; check grounding equipment ; detect residual or induced voltages.