NFPA 70E 2024 Article 120.6 Process for Establishing and Verifying an Electrically Safe Work Condition, step (7) states: Use an adequately rated portable test instrument to test each phase conductor or circuit part at each point of work to test for the absence of voltage. Test each phase conductor or circuit part both phase-to-phase and phase-to-ground. Before and after each test, determine that the test instrument is operating satisfactorily through verification on any known voltage source. This is known as the "live dead live" test and is to help you ensure your meter is working correctly.
Below is a picture of a meter verifying voltage where 120VAC/240VAC is expected but 177VAC/358VAC was measured. After verifying on a known source it was determined the meter had a bad battery in it (it also did not have the proper category rating).
Simple issues with your meter can cause serious issues for yourself. It's always important to verify you have the proper equipment, check to ensure it's working properly and follow NFPA 70E. We can help train you to identify these common hazards: https://www.70econsultants.com/training/