Codes and Standards (NEC Article 725, 760, 770, 800, 820; NC amendments)
What this domain covers
Codes and Standards tests your ability to open the right NEC article, apply the correct cable and installation rules, and recognize North Carolina amendments. The key articles are 725 (Class 1, 2, and 3 circuits), 760 (fire alarm), 770 (optical fiber), 800 (communications), and 820 (CATV and radio distribution).
Core rules
- Article 725 covers remote-control and signaling circuits. Class 1 circuits are not power-limited in the same way as Class 2 and 3; Class 2 and 3 are power-limited and have specific cable, separation, and marking rules. Class 2 cable is marked CL2; Class 3 is CL3.
- Article 760 covers fire alarm systems. Power-limited fire alarm cable is FPL, FPLR, or FPLP; non-power-limited fire alarm cable is NPLF, NPLFR, or NPLFP. Do not substitute communications cable for fire alarm cable.
- Article 770 covers optical fiber. Nonconductive fiber is OFN, OFNR, or OFNP; conductive fiber is OFC, OFCR, or OFCP. Plenum, riser, and general-purpose suffixes follow the same P/R/blank pattern.
- Article 800 covers communications circuits and cable: CM, CMR, CMP. Article 820 covers coaxial CATV and radio distribution cable: CATV, CATVR, CATVP. Coaxial shield grounding is required at the point of entry under 820.93.
- NFPA 72 governs fire alarm installation and performance; TIA-568 and TIA-569 govern structured cabling and pathways; the local AHJ enforces permits and inspections.
- North Carolina adopts the NEC through the NC Electrical Code, with amendments that can change the effective edition and local administrative requirements. Check the current NC code and local inspection department before design, especially for fire alarm and new commercial work.
Worked example
A designer specifies Cat 6 cable for a new fire alarm signaling line circuit because it is the same cable as the network. That is a code violation. Fire alarm cable must be listed for fire alarm use, such as FPLR in a riser or FPLP in a plenum, and the installation must comply with Article 760 and NFPA 72. The reasoning is that Article 800 cable is listed for communications, not for fire alarm survivability and supervision requirements.
Traps that cost marks
Applying Article 800 to fire alarm; using CM cable in a plenum; assuming a local amendment does not exist; treating plenum-rated as a complete installation method; and forgetting that the AHJ can require a permit and inspection even when the NEC does not name the job.