Help I can’t See Out, Egress Lighting for Dummies
The lights flicker and then darkness. You lean over to your spouse and whisper “don’t worry the lights will come on, ” you hope.
Then panic sets in, I know which way we came in (I think), but why did the lights go out? Was it a fire, power outage, or wait which way is out? You struggle to get to the door along with the 500 others watching the band that night. You stumble around chairs, tables, and the stairs leading to the main exit, hoping to not lose your spouse as they cling tight to your arm.
This scenario could play out daily in many different types of occupancies on a daily basis. As a code official one responsibility is to inspect egress lighting for operation for primary power and back-up power.
Normal illumination may be performed by artificial lighting and must meet the minimum requirements of the adopted code.
- Occupancies in Group U.
- Aisle accessways in Group A.
- Dwelling units and sleeping units in Groups R-1, R-2 and R-3.
- Sleeping units of Group I occupancies.
NFPA standards may provide requirements that are based on occupancy. Although the general focus is given out of NFPA 101 The Life Safety Code and the current edition was published in 2009. Bear in mind requirements based on occupancy can be found in additional sections of the code while chapter 7 provides the general requirements:
- 220.127.116.11 Illumination of means of egress shall be provided in accordance with Section 7.8 for every building and structure where required in Chapters 11 through 43. For the purposes of this requirement, exit access shall include only designated stairs, aisles, corridors, ramps, escalators, and passageways leading to an exit. For the purposes of this requirement, exit discharge shall include only designated stairs, aisles, corridors, ramps, escalators, walkways, and exit passageways leading to a public way.
- 18.104.22.168 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 22.214.171.124.2.
These requirements apply to all times the building is occupied including emergencies. The initial requirement is not intended to be emergency lighting. Emergency lighting is covered in IBC/IFC 1006.3 and 1006.4 (See NFPA 101 7.9).
The level of illumination is both codes is 1-foot candle measured at the floor on the required spaces. In assembly occupancies during performances or movies the walking surface can be reduced to 0.20 foot candle, that is typically restored to 1-foot candle on the activation of the fire alarm.
Emergency lighting ensures that the occupants can find the exit under a loss of power to the electrical system that is usually a accidental failure or man made failure. These systems are typically battery powered units that provide artificial light automatically on the loss of primary power. In addition some units receive their power from a stand-by generator (no more then 10 second delay when switching power sources, NFPA 101 126.96.36.199).
The areas typically covered by emergency lighting include (but not limited to):
- Designated stairs
- Passageways leading to an exit
- Areas in rooms required to have more then one exit
- Exit discharge in buildings required to have more then one exit
The required areas would have emergency lighting for a minimum of 90 minutes and provide 1-foot candle at the floor (see the adopted code for possibilities on reduced candelas at the end of the time period).
Emergency lighting equipment and battery systems for emergency luminaries shall be listed to ANSI/UL 924, Standard for Emergency Lighting and Power Equipment.
In order for the systems to work well they must be tested in accordance with the adopted codes and manufacture requirments.