Voltage testers check for difference in potential in electrical circuits. Measurement type and measurement range are the most important parameters to consider. There are three main measurement types: AC, DC, and AC / DC. For both alternating current (AC) and direct current (DC) voltages, the measurement range is the maximum voltage that instruments can measure. High voltage testers are designed for testing electrical equipment which operates at 600 V or higher for terminal-to-terminal operation, or 300 V or higher for terminal-to-ground operation. AC and DC power supplies with low voltage and high current are also considered to be high-voltage devices
