Hipot testers are electrical safety test devices that perform electrical compliance tests. Within the general category of electrical safety testing are a variety of equipment types that are specifically designed to test for electrical compliance. The individual equipment defines the kind of test performed.  Types of measurement performed by hipot testers include AC dielectric strength, DC dielectric strength, arc detection or tracking, insulation resistance, AC/DC selectable, and earth continuity.  An AC dielectric test measures the withstand capability of an insulator.  A DC dielectric test measures the withstand capability of an insulator.  Arc detection looks for external break-over during a test cycle.  Insulation resistance measures the resistance of an insulator or insulation during a test.  Some test equipment can measure both AC and DC inputs.  Earth continuity devices test electrical and electronic instruments and appliances to make sure they are functioning properly.  Electrical instruments that are substandard could fail and transfer dangerous current to their users.