OSHA requires at 1910.37(b)(6) that each exit sign “be illuminated to a surface value of at least five foot-candles by a reliable light source.” In addition, self-luminous or electroluminescent signs that have a minimum luminance surface value of at least .06 footlamberts (0.21 cd/m2) are permitted. In other words, exit signs don’t necessarily need to be illuminated with a bulb, but must be illuminated to the five foot candle requirement.