NEC Article 760 and Electrical Requirements for Fire Alarm Systems
Scope and structure
Article 760 governs the wiring for fire alarm systems: initiating circuits, notification circuits, and control circuits. Part I is general, Part II covers non-power-limited fire alarm circuits, and Part III covers power-limited fire alarm circuits. Fire alarm circuits are not treated as ordinary Class 2 or Class 3 circuits under Article 725; PLFA has its own rules in Part III, and that distinction is a favorite exam item.
Installation points tested
- Conductors and cable must be listed for fire alarm use; typical types are FPL, FPLR, and FPLP.
- Plenum and air-handling spaces require plenum-rated cable per 300.22(C).
- PLFA cables must be separated from light and power conductors by a fixed distance or a permanent barrier.
- NPLFA circuits need higher insulation ratings, overcurrent protection at the source, and standard Chapter 3 wiring methods.
- The disconnecting means for the fire alarm circuit must be permanently identified, marked as fire alarm circuit control, and colored red.
- Support, securing, and raceway fill follow the Chapter 3 and Chapter 9 rules referenced by Article 760.
- Grounding follows Article 250 requirements for the circuit type involved.
Worked example
A contractor runs PLFA cable through a return-air plenum above a corridor ceiling using FPLR because it was on the truck. The inspector rejects it: FPLR is a riser rating, not a plenum rating, and 300.22(C) requires the plenum-listed cable in that space. Replacing it with FPLP, or installing it in a raceway permitted for the space, resolves the violation.
Traps that cost marks
- Treating fire alarm cable as ordinary Class 2 cable under Article 725.
- Using FPLR or FPL where plenum cable is required.
- Forgetting that NPLFA and PLFA have different installation rules.
- Missing the red, permanently marked disconnecting means.