Section R. 408.10686 - Sign illumination and letter sizeRule 686.
(1) An exit sign shall be illuminated to a surface value of at least 5 foot-candles (54 lux) by a reliable light source and be distinctive in color. Self-luminous or electroluminescent signs that have a minimum luminance surface value of at least .06 foot lamberts (0.21 cd/m2) are permitted.(2) An exit sign shall have the word "EXIT" in plainly legible letters not less than 6 inches (15.2 cm) high, with the principal strokes of the letters in the word "EXIT" not less than 3/4 of an inch (1.9 cm) wide.(3) An internally illuminated exit sign shall be provided where the reduction of normal illumination is permitted and less than 5 footcandles would appear on the exit sign.Mich. Admin. Code R. 408.10686
1979 AC; 2015 MR 8, Eff. April 29, 2015