Mike Dolt Enterprises
Mike Dolt Enterprises
User: Misha322, Location: DC area
Asked on: Saturday, March 26, 2011 at 1:46 pm EDT
Answered on: Tuesday, May 14, 2024 at 3:19 am EDT
Question: I am having a hard time understanding to what lighting level should path of egress (corridors, parking garage isles, etc.) need to be lit to. In IBC section 1006.2 it states "not less than 1 footcandle) and in section 1006.4 "at least an average of 1 footcandle". NFPA 101, Life Safety Code has the same verbiage, 7.8.1.3 "at least 1 ft-candle" and 7.9.2.1 "an average of 1 ft-candle".Which is it, a minimum or an average of 1 footcandle?
The lighting level for paths of egress should be "an average of 1 footcandle" according to both the International Building Code (IBC) and the National Fire Protection Association (NFPA) 101, Life Safety Code.
Explanation
IBC Section 1006.4
"Artificial light sources shall provide not less than the following minimum requirements for illumination of means of egress: ... (2) Illumination of corridors, passageways, exit access stairways, exit ramps, exit doors, and exterior exits shall have an average of 1 footcandle at floor level."
NFPA 101 Section 7.9.
2.1
"Areas of exit access shall be illuminated with electric lights to an average of not less than 1.0 footcandle (10.8 lux)."The distinction between "not less than 1 footcandle" and "an average of 1 footcandle" is subtle but important:
"Not less than 1 footcandle" means that there should be no areas where the illumination level drops below 1 footcandle. "An average of 1 footcandle" means that the average illumination level over the entire space should be at least 1 footcandle. This allows for some areas to have slightly lower illumination levels, as long as the overall average is still 1 footcandle or higher.In practice, it is recommended to design for an illumination level slightly above 1 footcandle to ensure that the minimum illumination level is maintained even with some variation in the lighting conditions. Flag for review