Hi Jim, I often mention in my sessions that testers/ test instruments are a lot like extension cords. We take them for granted and they are always there like "old reliable". With test instruments particularly when first purchased, we are quick to throw out the manual with the packaging. A great deal of information is contained there such as calibration recommendations, temperature limitations, fuse, what certain symbols mean... Many companies have tailboard meetings, however, when was the last time you had a tailboard meeting that was electrical-related? The supervisor can instruct their workers to all get their tester and perform an inspection and test on a known live source. When was the last time one installed new batteries? During the Lockdowns, I recall using a test instrument outdoors in sub-zero temperatures. I kept getting strange readings, turns out I was using the tester in an environment beyond the temperature limitations. I found this out later when I checked the owner's manual.