National Electrical Code Explanations
Based on the 2020 NEC
National Electrical Code Tips: Article 760, Fire Alarm Systems, Part 7
Understanding the listing requirements of fire alarm circuit cables can help you make sense of the cable alphabet soup. Here are some highlights from Part IV of Article 760.
- Part IV, Listing Requirements, consists of two Sections: 760.176 and 760.179. And they are both pretty long, as far as sections go.
- 760.176 provides the requirements for the listing and marking of NPLFA cables.
- 760.179 provides the requirements for the listing and marking of PLFA cables (and for insulated continuous line-type detectors).
- Table 760.154 shows the permitted applications for listed PLFA cables in buildings. There's not an equivalent table for NPLFA cables.
- Table 760.154(A) shows the permitted cable substutitions for Cable Type FPLP, FPLR, and FPL. Type CMP can substitute for any of these.
- Table 760.176(G) explains the meaning of cable markings NPLFP, NPLFR, and NPLF. The equivalent Table for power-limited is 760.176(I). Make sure you NEVER confuse NPLFP with NPLFR.
- NPLFA conductors must be copper [760.176(A)]. While you may be permitted to get away with using aluminum in other parts of your fire alarm system or even premises wiring, it's a bad engineering decision to do so. The aluminum conductor people hate it when I say that, but the physics are what they are. Go with copper, accept no substitutes.
Text new with the 2014 revision provides requirements for Circuit Integrity (CI) cables and it's been modified a bit since that introduction. Among the requirements, CI cables can be installed only in a raceway where specifically listed and marked as part of an electrical circuit protective system [760.176(F)].
- And text new with the 2014 revision provides requirements for the electrical circuit protective systems just mentioned. Among those, the hourly rating must be printed on the outer jacket of the cable [760.176(G)].
- Insulated continuous line-type fire detectors, mentioned earlier, get scant coverage in 760.179. A few lines are tacked on at the very end, in 760.179(J). Among the requirements, the jacket must have a high degree of abrasion resistance. It's probably best if you don't run your sander on it for something to do while awaiting approval on the corrections you suggested to the drawing that young pup engineer got wrong. I'm just saying....
How the NEC is arranged
- The first four Chapters of the NEC apply to all installations.
- Article 90 precedes Chapter One, and establishes the authority of the NEC.
- Article 80 follows the body of the NEC; it exists as Annex H. It provides the requirements for administration.
- Chapters 5, 6, and 7 are the "special" chapters, covering special: occupancies, equipment, and conditions (in that order).
- Chapter 8 provides the requirements for communications systems.
- Chapter 9 provides tables.
- The appendices provide mostly reference information.
- Appendix D contains examples that every NEC user should study.
Try your NEC moxy:
- Do you know the difference between bonding and grounding? Hint: Look in the NEC, Article 100.
- Does the NEC refer to grounding incorrectly in any of its articles? Yes! So be careful to apply the Article 100 definitions. Don't ground where you should bond.
- When doing motor load calculations, which Article covers hermetic motors? Answer: While Article 440 covers the application of hermetic motors, it does so only by amending Article 430 because hermetic motors are a special case of motors. For motor load calculations, refer to Article 430.
- Does the NEC provide a voltage drop requirement? Yes! It does so in a special case, which is Article 648 Sensitive Electronic Equipment. But for general applications, it does not provide a requirement; it merely provides a recommendation in a couple of FPNs.
- Take our Code Quizzes.
Remember other applicable codes, rules, standards, and references:
- OSHA's electrical worker safety rules.
- IEEE standards.
- NETA standards.
- NFPA standards.
- International Codes (if applicable to the installation).
- State Codes (if the state has them).
- Local ordinances and permit requirements.
- Local fire codes.
- Manufacturer requirements or guidelines.
- Customer security requirements.
- Industry standards.
- Your company's own internal standards, practices, and procedures.
- Engineering drawing notes.
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