Wiring Methods, Installation Requirements, and Electrical Safety
Domain 7 tests NEC Article 760 wiring methods and field installation practices. The exam wants the correct cable or raceway for the environment and proper separation from power wiring.
Core rules
- Fire alarm cable types include FPLR for risers, FPLP for plenums, and FPL for general use where permitted; PLFA and PLTC apply to power-limited circuits under Article 760.
- A cable installed in a return-air plenum must be listed for plenum use, such as FPLP. A cable run between floors must be riser-rated or installed in a raceway.
- Maintain required separation from power conductors and use separate boxes unless the box is listed for the combination.
- Support cables per the manufacturer and code, protect from physical damage, and firestop penetrations.
- Do not use NM cable for fire alarm circuits; Article 760 does not permit it.
Worked example
A riser cable leaves a first-floor panel and runs through a return-air ceiling plenum before entering a second-floor conduit. The plenum portion must be FPLP or installed in a raceway. The vertical portion must be FPLR or in a raceway. Using general FPL cable in either location fails the listing requirement even if the conductors are electrically adequate.
Traps
- Using NM cable for fire alarm wiring.
- Running non-plenum cable through a return-air space.
- Sharing a raceway with power conductors without meeting separation rules.
- Omitting firestopping at rated penetrations.