Safety Tidbit #46 – Illumination of Emergency Exit Signs

Safety Tidbit #46 – Illumination of Emergency Exit Signs

I have a short topic this week.  In Safety Tidbit #8 I wrote about emergency exits.  However, I wish to discuss a very specific point this week – illumination.

By way of review, and as most of you are aware, each exit must be clearly visible and marked by a sign reading “Exit [1910.37(b)(2)]. And each doorway or passage along an exit access that could be mistaken for an exit must be marked "Not an Exit" or similar designation, or be identified by a sign indicating its actual use (e.g., closet) [1910.37(b)(5)]. Furthermore, if the direction of travel to the exit or exit discharge is not immediately apparent, signs must be posted along the exit access indicating the direction of travel to the nearest exit and exit discharge. Additionally, the line-of-sight to an exit sign must clearly be visible at all times. [ 1910.37(b)(4)]

So what about the signs themselves?  Each exit sign must have the word "Exit" in plainly legible letters not less than six inches (15.2 cm) high, with the principal strokes of the letters in the word "Exit" not less than three-fourths of an inch (1.9 cm) wide. [1910.37(b)(7)] And lastly, each exit sign must be illuminated to a surface value of at least five 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. [1910.37(b)(6)]

So the question came to me, does the exit sign have to be lit?  Answer: “Illuminated to a surface value of at least five foot-candles by a reliable light source.”  Foot-candles are a measurement of light at an illuminated object. For instance, the illumination on a very dark day may be 10 foot-candles. Whereas, Twilight may be only 1 foot-candle. (http://www.engineeringtoolbox.com/light-level-rooms-d_708.html) So, if your company only works one shift during the day your exit sign probably has enough natural light on it.  However, if you have no windows or your company works after sundown then electricity or electroluminescent signs will be necessary.

Remember the objective is to get people out of the building as quickly and efficiently as possible. Which brings up another point, what is the purpose of putting floor plans showing the exits and exit routes by an exit? More on that at a later date.

Hope this was helpful and thanks for reading Safety Tidbits  ~ Bryan