Which wiring method is a two-hour rated method in the context of fire alarm systems?

Which wiring method is a two-hour rated method in the context of fire alarm systems?

• A. Type NM-B
• B. Type THHN
• C. Type FPLP-CI cable
• D. Type XHHW-2

Answer: (C)

Wiring in fire-rated installations must be a listed method that can maintain circuit integrity for a specified period in a fire. A two-hour rating means the cabling method is tested and listed to resist fire for two hours, protecting the fire alarm circuit as flames spread. Among common options, only FPLP-CI cable is specified with a two-hour fire-resistance rating, making it suitable for routing through fire barriers or between floors in fire alarm systems. The other types are standard building conductors not rated for two-hour fire resistance: NM-B is typical residential cable not intended for fire-rated barriers; THHN is an individual conductor used in conduit and doesn’t by itself define a two-hour rated assembly; XHHW-2 is insulation for conductors used in wet or outdoor locations, but not a two-hour fire-rated cable for such assemblies.

Wiring in fire-rated installations must be a listed method that can maintain circuit integrity for a specified period in a fire. A two-hour rating means the cabling method is tested and listed to resist fire for two hours, protecting the fire alarm circuit as flames spread.

Among common options, only FPLP-CI cable is specified with a two-hour fire-resistance rating, making it suitable for routing through fire barriers or between floors in fire alarm systems. The other types are standard building conductors not rated for two-hour fire resistance: NM-B is typical residential cable not intended for fire-rated barriers; THHN is an individual conductor used in conduit and doesn’t by itself define a two-hour rated assembly; XHHW-2 is insulation for conductors used in wet or outdoor locations, but not a two-hour fire-rated cable for such assemblies.