October 7, 2020
By: Michael Shulman, UL principal engineer
Luminaires are addressed in several sections of the National Electrical Code (NFPA 70, the NEC), most specifically in Articles 410 and 411. Emergency luminaires are subject to additional regulations, not only in Article 700 of the NEC but also in Section 7.9 of the Life Safety Code, NFPA 101. These Codes require emergency luminaires to be maintained and periodically tested to validate that they are ready for service. The Standard for Emergency Lighting Equipment (UL 924) in turn requires the luminaire to have features that allow for this testing to occur. The basic premise is to ensure that, upon loss of the normal utility power, the emergency lighting will provide sufficient illumination to facilitate the orderly and efficient evacuation of the building’s occupants. The regulations specifically ask the emergency lighting system to provide a minimum average level of illumination (1 foot candle, measured on the floor) between wherever people may be in the building and where they need to go (typically, outside the building to a public right of way). It covers hallways, stairwells, open office spaces, restrooms, and most everything in between; NFPA 101 defines this “Means of Egress” as “A continuous and unobstructed way of travel from any point in a building or structure to a public way.”
To verify compliance with these regulations, emergency luminaires must be fixed in place. That doesn’t mean that portable luminaires (with batteries) or even handheld devices like flashlights and cell phones cannot (or should not) be used to assist with a building evacuation, but the building will get no credit for them because there is no assurance that they will be available when needed. Only those luminaires that are part of the building infrastructure, and that therefore can reasonably be expected to be operational (in part due to the code-required maintenance and testing protocols), can be used to establish building compliance with NEC Article 700 and NFPA 101 Chapter 7.9.
In combination with LED efficiency improvements, power capacity advances (primarily with lithium chemistries) have spurred the introduction of battery backup power within many types of luminaires. Referring to these battery-backup products as “emergency luminaires,” however, may not be appropriate unless they comply with the applicable safety standard (UL 924) and are installed in accordance with the applicable codes. One such requirement in UL 924 is that the equipment is fixed in place.
An interesting recent development is tubular LED lamps (TLEDs) that can incorporate both driver electronics and a back-up battery. “Type A” TLEDs have standard ANSI pins to fit into legacy fluorescent bi-pin lampholders, and they are suitable for connection directly to a fluorescent ballast without any rewiring of the luminaire. A type A TLED with battery back-up would seem to provide a quick and easy way to upgrade an existing fluorescent luminaire to LED and “emergency luminaire” status. But ANSI-base lamps are considered consumables and are not part of the facility infrastructure. This type of lamp could subsequently be replaced, during normal facility maintenance and outside of any Fire Marshal regulatory oversight, by a standard fluorescent tube. There are several regulations within NEC Article 700 that speak to the concept of limiting access and control of emergency lighting to qualified and authorized personnel. While this new lamp type is not specifically addressed (yet), the ease at which required emergency lighting could be inadvertently undermined should not be lost on professionals working in this field.
UL 924 requires emergency luminaires to have “…means for permanent mounting” (clause 11.1) with an exception for equipment that weighs 100 pounds or more. A recently approved revision to the standard will allow a broader range of luminaires to be electrically supplied by cord-and-plug, to accommodate high bay (and similar) luminaires that are permitted to use such supply connection means and that can serve a constructive role in providing emergency illumination in certain facilities. Unit equipment (sometimes referred to as a “bug eye” luminaire that illuminates a space only when normal power is lost) is also permitted a cord-and-plug supply arrangement, but the supply receptacle is typically located high up on the wall where inaccessible to facility occupants. In both cases, the equipment is mechanically secured (fixed-in-place) to its approved location.
Like most regulations dealing with changing technology, this is an area that is subject to review during both the normal Code revision cycle (every three years) and whenever new and innovative products are submitted for certification. An understanding of the intent behind the regulations is vital when assessing whether a product can be certified within the existing requirements, or whether the requirements can (and should) be modified in ways that support their purpose while expanding the range of compliant product choices. This is where process transparency and the involvement of a broad stakeholder community in standard and code development are of great value. The UL 924 Standards Technical Panel is exactly such a community, with many members also actively participating in the work of the NEC and NFPA 101.
Emergency lighting is everyone’s business, and it is important that we are thoughtful and thorough when advancements in technology offer possibilities not previously available.
