Fire Alarm, Security, and Communication Systems
Fire alarm circuits
NEC Article 760 divides fire alarm circuits into non-power-limited fire alarm (NPLFA) and power-limited fire alarm (PLFA) circuits. NPLFA circuits use Chapter 3 wiring methods. PLFA circuits use permitted power-limited cable, typically FPL, FPLR, or FPLP depending on the location. NFPA 72 supplies installation, performance, and survivability requirements that the NEC does not duplicate. Fire alarm cable must be separated from power conductors as required by Article 760.
Security and communications
Security, access control, and intercom circuits are usually Class 2 or Class 3 under Article 725. Communications circuits fall under Article 800. These systems must use the cable rating required for the environment and must maintain separation from power. A security contractor cannot simply use any leftover CL2 cable for a fire alarm notification circuit.
Worked example
A notification appliance circuit runs through a plenum and then a vertical riser. The plenum portion requires FPLP. The riser portion requires FPLR at minimum. If the contractor uses FPLP for the entire run, that is acceptable because the plenum rating is higher. Using CL3P in place of FPLP is not acceptable merely because both are plenum-rated; the cable must be listed for fire alarm use.
Traps that cost marks
- Substituting CL2 or CL3 cable for FPL cable on a fire alarm circuit.
- Forgetting that a plenum rating and a fire alarm listing are different requirements.
- Mixing fire alarm and power conductors without the required separation.
- Ignoring NFPA 72 survivability or performance requirements.