Most of the time i don't like to work on anything hot,But sometimes i have to and YES it has to be live. Why? trouble shooting is one reason alot of the time you need the power on to find the problem. Other times you need to work things live because of plant work, like putting disconnects on busways, this is nasty work in a plant that has been working for 60 yrs with 3inches of powder metal on the busways. Somebody has to do it. big guy
