The power supply for means of egress illumination shall normally be provided by the premises' electrical supply.
In the event of power supply failure in rooms and spaces that require two or more means of egress an emergency electrical system shall automatically illuminate all of the following areas:
In the event of power supply failure, in buildings that require two or more means of egress, an emergency electrical system shall automatically illuminate all of the following areas:
- Interior exit access stairways and ramps
- Interior and exterior exit stairways and ramps.
- Exit passageways.
- Vestibules and areas on the level of discharge used for exit discharge in accordance with Section 1028.1.
- Exterior landings as required by Section 1010.1.6 for exit doorways that lead directly to the exit discharge.
In the event of power supply failure, an emergency electrical system shall automatically illuminate all of the following areas:
- Electrical equipment rooms.
- Fire command centers.
- Fire pump rooms.
- Generator rooms.
- Public restrooms with an area greater than 300 square feet (27.87 m2).
The emergency power system shall provide power for a duration of not less than 90 minutes and shall consist of storage batteries, unit equipment or an on-site generator. The installation of the emergency power system shall be in accordance with Section 604.
Emergency lighting facilities shall be arranged to provide initial illumination that is not less than an average of 1 footcandle (11 lux) and a minimum at any point of 0.1 footcandle (1 lux) measured along the path of egress at floor level. Illumination levels shall be permitted to decline to 0.6 footcandle (6 lux) average and a minimum at any point of 0.06 footcandle (0.6 lux) at the end of the emergency lighting time duration. A maximum-to-minimum illumination uniformity ratio of 40 to 1 shall not be exceeded. In Group I-2 occupancies, failure of any single lighting unit shall not reduce the illumination level to less than 0.2 foot-candle (2.2 lux).