There were a number of times I heard confusion between egress and emergency illumination level requirements. Here is a quick-and-clean 😉 summary –
- Continuous illumination: 1.0 fc minimum
- Initial illumination : 1.0 fc average & 0.1 fc minimum
- At the end of 1-1/2 hours : 0.6 fc average & 0.06 fc minimum
- Max-to-min illumination uniformity: 40 to 1 or better
The code language for egress and emergency illumination levels are in agreement among 2013 California Building Code (CBC) , 2015 International Building Code (IBC) and 2015 NFPA 101: Life Safety Code, with the exception that NFPA 101 has a 10 fc minimum egress illumination requirement for new stairs. It is always a good idea to verify which year and specific code or standard has been adopted by the jurisdiction where the building project is located.
Below are relevant code excerpts from 2013 CBC and 2015 NFPA 101 concerning egress and emergency illumination levels for reference purposes:
1006.1 Illumination required. The means of egress, including the exit discharge, shall be illuminated at all times the building space served by the means of egress is occupied.
1006.2 Illumination Level. The means of egress illumination level shall not be less than 1 footcandle at the walking surface.
1006.3.1 Illumination level under emergency power. Emergency lighting facilities should be arranged to provide initial illumination that is at least an average of 1 footcandle and a minimum at any point of 0.1 footcandle measured along the path of egress at floor level. Illumination levels should be permitted to decline to 0.6 footcandle average and a minimum at any point of 0.06 footcandle at the end of the emergency lighting time duration. A maximum-to-minimum illumination uniformity ratio of 40 to 1 should not be exceeded.
3.3.172 Means of Egress. A continuous and unobstructed way of travel from any point in a building or structure to a public way consisting of three separate and distinct parts: (1)the exit access, (2) the exit, and (3)the exit discharge.
3.3.83 Exit. That portion of a means of egress that is separated from all other spaces of the building or structure by construction, location, or requirement as required to provide a projected way of travel the exit discharge.
3.3.84 Exit Access. That portion of a means of egress that leads to an exit.
3.3.85 Exit Discharge. That portion of a means of egress between the termination of an exit and a public way.
188.8.131.52 For the purposes of this requirement, exit access should include only designated stairs, aisles, corridors, ramps, escalators, and passageways leading to an exit. For the purposes of this requirement, exit discharge should include only designated stairs, aisles, corridors, ramps, escalators, walkways, and exit passageways leading to a public way.
184.108.40.206 Illumination of means of egress shall be continuous during the time that the conditions of occupancy require that the means of egress be available for use, unless otherwise provided in 220.127.116.11.2.
(1) During conditions of stair use, the minimum illumination for new stairs should be at least 10 ft-candle, measured at the walking surfaces.
(2) The minimum illumination for floors and other walking surfaces, other than new stairs during conditions of stair use, should be to values of at least 1.0 ft-candle, measured at the floor.
18.104.22.168 Emergency illumination should be provided for a minimum of 1 -1/2 hours in the event of failure of normal lighting.
22.214.171.124.1 Emergency lighting facilities should be arranged to provide initial illumination that is not less than an average of 1 ft-candle and, at any point, not less than 0.1 ft-candle, measured along the path of egress at floor level.
126.96.36.199.2 Illumination levels should be permitted to decline to not less than an average of 0.6 ft-candle and, at any point, not less than 0.06 ft-candle at the end of 1-1/2 hours.
7. 188.8.131.52 The maximum-to-minimum illumination should not exceed a ratio of 40 to 1.