High-Rise Riser: Pathway Survivability Through a Shared Closet
An 8-story, 160,000 sq ft high-rise is fully sprinklered and has a new voice evacuation system. The FACP is in the basement; the riser to floor 8 runs 240 ft through a tenant electrical closet and a public corridor. The contractor proposes 16 AWG FPLR cable in EMT for the speaker and data risers, with no 2-hour rating. The electrical closet also contains tenant panels and a water heater. LAFD plan check has required pathway survivability for the high-rise. The contractor argues that because the building is sprinklered, Level 1 is allowed and the EMT provides physical protection. The electrical inspector has already approved the EMT. The owner wants to avoid a 2-hour shaft because of cost. The designer asks whether the riser can be accepted as proposed with firestopping at the floor penetrations.
1. How should the designer determine the required pathway survivability level, and is the sprinklered-building argument sufficient?
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Do not accept “sprinklered equals Level 1” as a blanket rule. First identify the required level from the adopted building code, LAMC fire alarm provisions, and the LAFD high-rise requirements for this occupancy. NFPA 72 defines survivability levels and permits different methods: Level 2 generally requires a 2-hour circuit-integrity cable or a listed 2-hour raceway/enclosure; Level 3 requires a 2-hour enclosure plus CI cable. A sprinklered building may qualify for a reduced level only where the specific adopted code exception applies, and the designer must confirm that the exception is not limited by occupancy, height, or the location of the pathway. The electrical closet with tenant panels and a water heater is a fire risk and a separation issue. Firestopping at floor penetrations seals openings but does not make FPLR cable in EMT a 2-hour pathway. The designer should request a written LAFD interpretation before construction.
2. Evaluate the proposed 16 AWG FPLR in EMT for the 240-ft riser. What is wrong, and what alternatives exist?
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FPLR is a listed fire alarm cable, but it is not a circuit-integrity (CI) cable, and EMT alone is not automatically a 2-hour rated raceway unless it is listed/approved for that use. Therefore the proposal does not demonstrate Level 2 or Level 3 survivability. The 240-ft run through a tenant electrical closet and public corridor also exposes the riser to fire and mechanical damage from other tenants. Alternatives: (1) install a listed 2-hour CI cable for the speaker and data risers; (2) use a listed 2-hour enclosure or shaft, with the cable inside; (3) relocate the riser to a dedicated 2-hour rated shaft; or (4) obtain an approved alternative based on a fire engineering analysis. The 16 AWG size is a separate issue: check voltage drop for the speaker load over 240 ft; if the load is significant, 16 AWG may be inadequate even if the survivability method is corrected. Submit the selected method with listings and firestopping details.
3. What should the contractor submit to LAFD to resolve this before rough-in inspection?
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Submit a revised pathway survivability plan showing the exact route, the required level, and the method of protection for each segment. Include listings for the CI cable or 2-hour enclosure, raceway details, firestopping and penetration details, and separation from tenant equipment. Provide voltage-drop calculations for the speaker circuits at the actual load and length. Include a narrative explaining why the proposed method meets the adopted code and any request for an alternate means or variance. Do not proceed with rough-in until LAFD plan check has approved the method; field changes after inspection can force removal. Coordinate with the electrical inspector, but remember that electrical approval of EMT does not equal fire alarm pathway survivability approval.