Emergency lighting: What’s required, and how it’s designed

Emergency lighting is required in all nonresidential buildings. There are numerous versions of building codes and various editions of these building codes in use around the country.

07/16/2018


Learning objectives

  • Understand where emergency lighting is required in nonresidential buildings, as required by codes and standards.
  • Learn about performance requirements for emergency lighting.
  • Comprehend how emergency lighting is implemented, and which devices should be used. 

Emergency lighting is required to illuminate building areas when things go wrong—for example, when the normal electrical supply is interrupted by a utility outage or by a fire or failure within the building. In most facilities, the largest part of emergency illumination lights the pathways and exits that lead out of the building—the egress paths. Its intent is to facilitate evacuation of the facility, particularly in the event of a fire, and to reduce the tendency of occupants to panic under stress, and in the dark.

Figure 1: This rendering provides an example of how the emergency lighting system might illuminate a hallway in an office building. Courtesy: Smith Seckman Reid Inc.Because the performance of emergency lighting is directly related to life safety, code officials are notoriously demanding of strict compliance in its design and installation. Differing interpretations about emergency lighting requirements easily can lead to a costly delay of occupancy. A clear understanding of the code requirements for emergency lighting, and a clear understanding of code officials' views of any issues that admit interpretation, will go a long way toward avoiding expensive and embarrassing surprises late in construction.

The term "emergency lighting" appears frequently in the codes, but it is nowhere directly defined. For the purposes of this article, emergency lighting refers to lighting equipment that is specifically identified as such in one of the codes, with limited exception. Certain lighting that must illuminate under emergency conditions in health care facilities, but is not technically defined as emergency lighting, is addressed separately.

These codes are referenced in this article:

Code-enforcement agencies may adopt these codes, or other codes, and may enforce other editions. Provisions of the various codes sometimes differ regarding similar sets of requirements. Designers should verify the codes and editions in force, and consult authorities having jurisdiction (AHJ) regarding their interpretations of ambiguous or conflicting requirements, before design commences. 

Emergency egress lighting, and other emergency lighting

The existential requirements for emergency lighting appear independently in the IBC and in NFPA 101. IBC Section 1008, Means of Egress Illumination, covers lighting requirements for exit routes. It calls for egress lighting for nearly all occupancies, with limited exceptions for agricultural and livestock buildings, dwelling units in institutional occupancies and most residential occupancies, and aisles in assembly occupancies. Egress lighting must remain active whenever the building is occupied (IBC 1008.2).

Figure 2: A wall-mounted battery-powered incandescent egress luminaire was installed in an elevator lobby in a Texas condominium. The test switch and pilot light can be seen at the bottom of the luminaire. Courtesy: Smith Seckman Reid Inc.Under normal conditions, egress lighting must be served by the building's primary electrical supply. When that supply fails, an emergency power supply must illuminate specific areas, particularly pathways that lead to exits, the exits themselves, and exit discharges. The IBC allows for a number of options for the form of the emergency power system. It may be an onsite generator, a battery-powered system, or a distributed set of batteries attached to individual luminaires.

NFPA 101 provides a similar set of requirements. Emergency lighting is required for egress in all occupancies addressed by the code, with the exception of one- and two-family dwellings and rooming houses. Overall, NFPA 101 describes emergency lighting requirements more specifically than does the IBC.

The IBC generally applies to new construction and renovation projects. Its provisions are not normally enforced retroactively on existing buildings, except where the AHJ determines that public safety is compromised by existing conditions (IBC 102.6). NFPA 101 is enforceable on existing buildings and includes separate requirements for existing and new facilities for each type of occupancy that it addresses.

For emergency lighting, NFPA 101 requirements for new and existing facilities are substantially identical, with a few exceptions. Certain existing worship venues, for example, are permitted to operate without emergency lighting under NFPA 101, while similar new facilities are required to provide it (NFPA 101 12.9.9.2, 13.2.9.3). 

Locations

Figure 3: A battery-powered fluorescent luminaire in an office corridor shows the test switch and pilot light. It incorporates a battery ballast, which illuminates one of three fluorescent tubes when power fails. Courtesy: Smith Seckman Reid Inc.NFPA 101 requires emergency egress lighting in exit accesses, at exits, and at exit discharges. For this purpose, the term "exit access" denotes only designated stairs, corridors, ramps, escalators, and passageways leading to an exit. "Exit discharge" denotes similar designated building components leading to a public way. In a typical design project, these building components are designated by the architect and indicated in the life safety plans. When those plans are not available early in the design process, the designer can get very close to compliant egress lighting by providing emergency lighting in corridors, stairways, at exits, and immediately outside exits.

The IBC specifically requires emergency lighting in certain spaces not used for egress: electrical rooms, fire command centers, fire pump rooms, and generator rooms. No special performance characteristics are specified for these areas. A minimal interpretation would be that these areas require egress illumination. That solution might be suitable for utility spaces, where emergency light would provide wayfinding and be supplemented by portable battery-powered lamps. However, egress-level lighting would certainly be inadequate for a fire command center. A conservative approach for a fire command center might be to provide adequate lighting on each of the normal and emergency power systems, to ensure that the failure of one of those systems won't leave the center in darkness. Given the IBC's ambiguity about emergency illumination in these areas, it is worthwhile to verify the AHJ's interpretation of the code during design.

Exit signs are required along the egress path, at doorways leading to an egress path, and at exits, placed to ensure that an exit sign is visible from no more than 100 ft or the listed viewing distance of the exit sign (IBC 1013.1). This requirement is echoed in NFPA 101 (7.10.1.5.1).

NFPA 110 7.3 requires battery-powered emergency lighting with an average illumination at floor level of 3 fc at generator sets and at generator paralleling gear (NFPA 110 7.3). This requirement also is in NFPA 99.

NFPA 99 calls for battery-powered lighting in locations where deep sedation or general anesthesia is used, with lighting levels sufficient to terminate procedures in the room. These battery lighting units are required to operate for at least 30 minutes (NFPA 99 6.3.2.2.11). The purpose of these battery-powered lights is to ensure that a surgeon wielding a scalpel will not be left in total darkness should normal power fail during a procedure, and to provide minimal lighting for terminating a procedure should the standby lighting also fail.

Technically, these lights are not emergency lights, as there is no emergency electrical system defined for health care facilities. The NEC allows these lighting units to be connected to the critical branch rather than the life safety branch. 


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