Multimeters use CAT ratings to show when it's safe to the use the meter due to possible hazardous overvoltage from the mains. Always make sure the meter's CAT level is suitable for your task! (src: https://www.adafruit.com/galleries/cats-of-engineering & https://www.maxpierson.me/2010/10/13/my-nixie-clock-build/) #electronics #cat #cats