The Fluke PRV240 Proving Unit provides a safe and convenient method for "test before touch" (TBT) verification of electrical test tools without placing the electrician or technician in potentially hazardous electrical environments. Three-point TBT verification of electrical test tools — verify the test tool is working properly before conducting a test, take the test, verify after the test — is an important safety development now required by GS38 and NFPA 70E work practices. Use of the PRV240 reduces the risk of shock and arc flash compared to verification of test instruments on high-energy sources in potentially hazardous electrical environments because the PRV240 provides a known voltage in a controlled, low-current state in accordance with safe work practices.