National Electrical Code Explanations

Based on the 2020 NEC

by Mark Lamendola

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.

  1. Part IV, Listing Requirements, consists of two Sections: 760.176 and 760.179. And they are both pretty long, as far as sections go.
  2. 760.176 provides the requirements for the listing and marking of NPLFA cables.
  3. 760.179 provides the requirements for the listing and marking of PLFA cables (and for insulated continuous line-type detectors).
  4. Table 760.154 shows the permitted applications for listed PLFA cables in buildings. There's not an equivalent table for NPLFA cables.
  5. Table 760.154(A) shows the permitted cable substutitions for Cable Type FPLP, FPLR, and FPL. Type CMP can substitute for any of these.


  6. 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.
  7. 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.



     

  8. 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)].

  9. 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)].
  10. 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....