National Electrical Code ExplanationsBased on the 2014 NEC
National Electrical Code Tips: Article 760, Fire Alarm Systems, Part 3
- If your alarm circuit is a Non Power Limited Fire Alarm circuit (NPLFA), then unlike the Power Limited Fire Alarm circuit (NPLFA) it's basically a Chapter 3 wiring job [760.46]. The special requirementse in Article 760 take up slightly more than two pages.
- You can run Class 1 and NPLFA in the same raceway [760.48(A)].
- You can run power supply and NPLFA circuit conductors in the same raceway too, but only if they connect to the same equipment [760.48(B)].
- You can't use aluminum conductors for fire alarm circuits [760.49(A)], and the conductors you do use must be rated at 600V or more [760.49(B)].
- You determine the raceway fill per 300.17 [760.51(A) and (B)].
- Multiconductor NPLFA cables have so many requirements attached to them, the requirements take up 3/4 of a page [760.53]. Before considering such a wiring method, read this subsection carefully.
- The requirements for Power Limited Fire Alarm (PLFA) circuits take up nearly twice as much room in the NEC as those for NPLFA circuits. And more than 25% of the material is new with the 2014 NEC.
- A PLFA power source must be one of three things: Listed PFLA or Class 3 transformer, listged PLFA or class 3 power supply, or listed equipment marked to identify the PLFA source [760.121].
- The branch circuit supplying this equipment cannot supply other loads [760.121(B)].
- Ensure any plainly visible equipment supplying PLFA circuits is durably marked to indicate each circuit that's a PLFA circuit [760.124].
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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