I teach NFPA 70E requirements to a large population of nuclear electrical workers most every year. There is one question that seems to pop-up a lot. Why do we need to wear non-melting clothing (100% percent cotton) with long sleeves when working in an energized panel rated at less than 1.2 calories/cm2? This is an interesting question. If there is not enough heat energy to give an person a second degree burn, is there enough heat energy to melt or ignite clothing? I'm not sure I really have a correct answer. Does anyone know the correct interpretation of this rule?