Using the Klein ET600 is quite easy. First, make sure the device is off before connecting the test leads. To measure insulation resistance, select the appropriate test voltage (125V, 250V, 500V, or 1000V) according to your needs. For AC/DC voltage testing, just switch to the voltage mode and the automatic ranging True RMS technology will handle the rest. You can use the lock function to keep the reading and the built - in stand for hands - free operation. When it comes to safety, always use the provided CAT III/CAT IV Safety Rated Test Leads. Avoid using it in wet or explosive environments. After each use, clean the device with a dry cloth. Store it in a cool and dry place to maintain its performance.