An electrical method for detecting the leakage position of exposed geotechnical film using an arc test Arc test method - this technique is suitable for dry, uncovered, clean (or slightly dirty) films placed directly on a sufficient conductive layer under an electrical insulating geomembrane. Contact the first electrode with a material or roadbed that is conductive enough. The second electrode, as a conductive probe with a very high voltage power supply, sweeps the test probe across the surface to check for leakage. When leakage occurs, a closed circuit and an arc are created to determine the location of the leakage point. The method can usually locate a leak with a diameter as small as 1mm.