Amprobe AT3-500 [3435058] Underground Cable Locator. The Amprobe AT-3500 Underground cable locator keeps productivity high while keeping operational costs low. The AT3500 is the rugged, economical solution for locating cable wires and pipes that are underground if they are energized or de-energized. Great for parking lot and airport lighting applications, it precisely pinpoints buried services, with exceptionally fast sound and meter response. The backlit, multiple-segment, bar graph, digital display, plus audible indicators easily locate cables and wires. The Amprobe AT-3500 cable locator employs the proven 33 kHz frequency for most locating applications. To avoid lines at utility construction sites, it also offers the highly sensitive power and radio modes. Take depth measurements with the simple press of a button.