Emergency lighting is lighting that either stays ON or automatically turns ON to facilitate safe and orderly building evacuation during a power outage.
Traditionally, emergency lighting solutions focused on dedicated battery-powered emergency units (e.g., “bug eye” luminaires) to provide the 1 footcandle of egress path illumination for at least 90 minutes, as required by code. While functional, they’re not attractive, sitting dark until needed.
The LED revolution produced many luminaires with built-in switching and dimming. This facilitated a trend of using the same luminaires for both general and emergency lighting, powered by battery, backup generator, or UPS. This eliminates emergency units but creates a control challenge. The dual-function luminaires must be controllable for energy management and visual needs, while overriding these inputs to power to full brightness during a power failure.
Luminaire producing application-specific light levels in normal operating mode (left) and egress light levels in emergency mode (right). Image courtesy of Hubbell Lighting.
Several codes regulate emergency lighting, the most influential arguably being the National Electrical Code (NEC) (NFPA 70) and the Life/Safety Code (NFPA 101). Other codes and standards may apply, such as UL 924 (emergency lighting and power equipment), UL 1008 (transfer switches), International Building Code, International Fire Code, and NFPA 110 and 111 (standby power systems). For specifics and interpretation for your project, consult the authority having jurisdiction.
Article 700 of the 2014 NEC added a requirement that directly controlled luminaires used for emergency lighting be listed (UL 924) for that use. The 2017 NEC and UL 924 define “directly controlled luminaires” as having the ability to automatically override any control setting and produce an appropriate light output/light level during a power outage.
According to Anthony Campbell, VP Brand Management, Hubbell Lighting, directly controlled luminaires on emergency circuits must be 924-listed, and so must any bypass device or control equipment featuring a built-in bypass device. If a device is used to transfer to emergency power in either a feeder or branch emergency circuit, it should be UL 1008-listed.
Michael Brown, Product Manager, Pow-R-Command Lighting Control, Eaton, said UL 924-listed directly controlled luminaires equipped with integral battery and loss-of-voltage sensing electronics can be controlled by remotely operated two-pole circuit breakers designed with normal and emergency lighting connections. Alternately, UL 924-listed relays can be used, available in switching-only and switching-and-dimming models. These relays are typically installed separately outside lighting relay panels or lighting control panelboards.
Project participants should review the listing of each component and then test the entire system to ensure code-compliant light levels are provided upon loss of power, whether that be by transfer, bypass, or control system state. The authority having jurisdiction may inspect the system to ensure compliance. Some manufacturers provide a test button to simplify testing.
Adoption of LED lighting with built-in control functionality is facilitating using luminaires for both normal and emergency lighting. The designer must take care to ensure these luminaires are properly listed and operate in accordance with life/safety codes, regardless of how they’re controlled during normal operation. Manufacturers can be a valuable source of support for challenging applications.
Dual Function Florescent Luminaires have been around for 40 Years. LED lighting was not the impetus for Dual function ceiling Luminaires. Furthermore, in a power-outage situation (emergency) these dual function luminaires are typically operated at a reduced light level which has been tested to provide the required illumination level for room/building egress.
Hi Jim, yes, you are correct, fluorescent dual-function luminaires have been around for a long time, I’m sorry if I wasn’t clear on that. LED has facilitated the trend because of the integrated control functionality available in many luminaires.