NFPA Journal

Why do we need to protect the installation of loudspeaker circuit wiring in high-rise buildings with two-hour construction?

For starters, this can prove very expensive, especially when we can also use two-hour rated cable, which the National Electrical Code® refers to as “circuit integrity cable”—a much more affordable alternative. As part of its initial deliberations for the 2022 edition of NFPA 72®, National Fire Alarm and Signaling Code®, the technical committee for Chapter 24 had to answer this question.

If you were to review recent editions of NFPA 72, past and present, you would identify a single important theme: all of the requirements and related annex material in the code, regardless of edition, promote reliable fire alarm system applications, design, and installations. This singular theme of reliability starts with the stated purpose in Subsection 1.2.1: “The purpose of this Code shall be to define the means of … the reliability of the various types of fire alarm systems, supervising station alarm systems, public emergency alarm reporting systems, fire and carbon monoxide detection and warning equipment, emergency communications systems, and their components.”

The specific application and installation requirements outlined in the code are intended to ensure that a fire alarm system meets the performance requirement of operational reliability. Of course, all requirements in the code represent minimums and reflect the operational goal that a fire alarm system must work when needed.

For example, the code specifies that the primary purpose of the fire alarm system is “to provide notification of alarm, supervisory, and trouble conditions; to alert the occupants; to summon aid; and to control emergency control functions.” Meeting this important goal requires that all designers and installers understand not only the “parts and smarts,” as defined by a fire alarm systems manufacturer, but also the requirements as outlined in the code. Although not as intriguing as a mystery novel, you must read and use the code in its entirety in order to consistently meet the installed fire alarm system’s total performance in accordance with the code’s intent.

For example, Chapter 12 contains the definition and performance for cable survivability requirements. Nothing in Chapter 12 requires an installer to use two-hour rated circuit integrity cable when installing a fire alarm system. Chapter 24 provides the first location where you can find a requirement for cable survivability. Only systems employing relocation, or partial evacuation, require the survivable performance of cable and associated equipment. What you will not find is the “why” for this specific requirement in the code. But if you think about the survivability requirement in Chapter 24, the unspoken performance requirement intends for the speakers on the floors above the fire floor to continue working during the suppression efforts. The speaker circuits inevitably pass through the fire floor and, in order for the fireground commander to continue to provide valuable information to those occupants and the floors above the fire, the circuits must have protection.

Can we reduce or eliminate this requirement? You can find the answer in the code. A new paragraph 24.3.14.4.1.1 states, “Where notification zones are separated by less than two-hour fire-rated construction, a pathway survivability of Level 1, 2, or 3 shall be permitted.”

Another new section provides relief from the two-hour requirement by using Class X or Class N wiring methods for all notification appliance circuits “installed with the incoming and outgoing pathways separated by at least one-third the maximum diagonal of the notification zone.”

Finally, the code does not require survivability, regardless of construction and building height, if the emergency plan does not employ relocation or partial evacuation of the occupants. It would appear that the 2019 edition of NFPA 72 resolves the question considered by the NFPA 72 Chapter 24 technical committee.

However, the technical committee has formed a task group to determine the need for any additional changes. The stated goal, after all, remains ensuring the reliability of the fire alarm system performance.

Wayne D. Moore is vice president at Jensen Hughes. NFPA members and AHJs can use the Technical Questions tab to post queries on NFPA 72 at nfpa.org/72.