Pathway Survivability for a Voice Riser Branch
A six-story assisted living facility has a voice evacuation system. The main fire alarm control panel is in the basement. The riser from the basement to floors 2 through 6 is installed in a two-hour rated electrical shaft. On floor 3, a branch circuit leaves the shaft in EMT and runs 45 ft through a one-hour rated corridor to serve corridor speaker/strobes. The EMT is not fire-rated, and the cable is FPLR. The designer says the shaft protects the riser and the branch is in metal conduit, so pathway survivability is satisfied. The AHJ has adopted NFPA 72 and requires Level 2 pathway survivability for the voice system. The building has a fire command center and a partial evacuation plan. The contractor wants to use the existing EMT to avoid cost.
1. Does the floor 3 branch satisfy Level 2 pathway survivability? Explain.
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No. The two-hour shaft protects the riser only while the circuit remains inside that enclosure. Once the branch leaves the shaft and runs 45 ft through a one-hour corridor in ordinary EMT, the branch is no longer protected by a two-hour enclosure. FPLR cable is a riser-rated cable, not a circuit integrity cable, and EMT alone does not provide a two-hour fire-resistive pathway. The designer's statement that metal conduit satisfies survivability confuses mechanical protection with fire-resistive protection. For Level 2, the pathway must remain operational for the required period using the methods recognized by NFPA 72, such as a two-hour rated enclosure, listed circuit integrity cable, or a listed raceway system with the required fire rating. The branch as described does not meet that standard.
2. What remediation options should the reviewer accept for the floor 3 branch?
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The reviewer should accept a method that actually provides the required survivability for the entire branch, not just the riser. Options include relocating the branch so it remains within the two-hour rated shaft or another two-hour rated enclosure until it reaches the floor 3 device location; using a listed circuit integrity cable or listed raceway system that is rated for the required fire exposure; or reconfiguring the system so the floor 3 notification appliances are served by a pathway that meets the required level. The contractor must provide manufacturer listings and installation instructions, not just a catalog number. If the existing EMT remains, it can be part of the support or mechanical protection, but it does not by itself satisfy the fire-resistive requirement. The final design should be shown on the riser diagram and accepted by the AHJ before installation.
3. What documentation should the AHJ require to confirm pathway survivability?
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The submittal should state the required pathway survivability level and show, on the riser diagram, where each pathway is protected and by what method. The contractor should provide listings for circuit integrity cable, fire-rated raceway, or two-hour enclosures, along with installation details for penetrations and supports. The documentation should identify the boundaries of the two-hour shaft and any point where a circuit leaves it. At acceptance, the record of completion should reference the pathway method and any inspection of the fire-resistive construction. The AHJ should also require as-built drawings if the routing changes. A note that the cable is in EMT is not sufficient documentation for Level 2 survivability.