Abstract: A testing device for testing a high or medium-voltage cable comprises a circuit arrangement with a test voltage generator, which comprises a low voltage-side earthing input and a high voltage-side output and is designed to provide a variable test voltage, a test specimen connection for connecting the high voltage-side output to a conductor of the cable, a protective earth connector for connecting to protective earth, a connecting conductor which electrically connects the low-voltage-side earth input to the protective earth connector, so that the connecting conductor represents a current collection point through which a measuring current flows during the test, and a high-frequency signal pick-up at the current collection point, at which a high-frequency pre-location signal is generated based on the measuring current.