Updates to UL 924 and Emergency Lighting

By Michael Shulman, principal engineer, Lighting

Shortly after publication of the 2020 edition of the National Electrical Code (NEC), the UL 924 Standards Technical Panel (STP) addressed several technology-related revision proposals that offered enhanced functionality and control options for emergency lighting systems. One topic of discussion was a developing technology that leverages real-time sensors and artificial intelligence to discern and adjust directional signage for optimal egress paths during an emergency. The UL 924 STP concluded with a consensus that the technology was not yet sufficiently mature for inclusion in the UL 924 safety Standard for emergency lighting systems. Instead, the STP decided that, at the time, buildings should rely on legacy static emergency lighting equipment.

The 2023 NEC was published in late fall of 2022, and UL 924 revisions that had been under consideration for most of that year were published in December 2022. Among these revisions are:

• Expanded and clarified requirements for using lithium-ion batteries.
• Application of the 10-second switchover time limit to emergency power for all control devices.
• Expanded descriptive content on the role of Power over Ethernet (PoE) equipment in emergency lighting systems.
• Guidance for the evaluation of emergency lighting systems consisting of remotely located but interdependent and interoperable devices.
• A full reorganization of the large set of requirements for equipment markings and instructions.

Many of the UL 924 revisions answer questions that arise during a time when the technology is changing rapidly, and the regulatory system is challenged to facilitate the deployment of potentially valuable building equipment enhancements while maintaining the established acceptable level of safety. In the case of emergency lighting, the regulatory system is built on establishing consensus among the stakeholder communities and charged with both driving consistency in how equipment is evaluated and establishing the reliability of performance claims. Product designers and producers are responsible for innovation, while regulators are accountable for facilitating responsible implementation. The UL STP process is where these two sides meet to collaborate.

The latest revision process started in January 2022 with a 17-topic proposal package. The STP’s preliminary review generated comments and follow-up discussions with individuals and industry groups. A virtual STP meeting was held in May 2022 to dive deeper into the comments and seek common ground. Several proposals were then revised, and balloting began in October 2022. One proposal related to communication-enabled equipment, software updates and cybersecurity was withdrawn based on discussions concluding it was too soon to prescriptively regulate a situation that is still evolving and changing rapidly. Another proposal related to the temperature test program for emergency LED drivers was rejected as an unneeded relaxation. The remaining 15 topics garnered unanimous support from the STP, and the revised Standard was published on Dec. 14, 2022.

As one cycle ends, another begins. We are now taking note of innovative equipment offering new forms to accomplish old functions, meeting the intent of UL 924 but doing so in ways not anticipated by the existing text. While UL 924 does not operate on the same fixed three-year schedule as the NEC or the Life Safety Code (NFPA 101, whose 2024 edition will be published late in 2023), past practice strongly suggests that it must keep up with innovation.

Download the latest addendum to UL 924 for details on the normative references and specific information about the scope and testing requirements or contact us to discuss your emergency lighting needs.