National Electrical Code Explanations
Based on the 2017 NEC
National Electrical Code Tips: Article 830, Network-Powered Broadband Communications Systems Part 1
- To understand the applicability of Article 830, read Informational Note 1 under 830.1 Scope. Specifically, if you can understand what a typical basic configuration is then you can use that concept to determine if the system you're working with is covered by Article 830 or not.
- Several other Articles may also apply [830.3]. For example, the requirements of 110.3(B) apply to the installation and use.
- These systems, by definition, have specific power limitations [830.15]. These aren't stated in a simple way. See Table 830.15 to get a handle on what they are.
- As with any other cabling installation, you can't block access to equipment that's behind panels [830.21]. The NEC repeats this requirement in every Article dealing with any kind of cabling that goes in ceiling spaces, even though it's common sense and should not require a specific Code rule that's repeatedly repeated. Even so, this rule is commonly violated!
- Another rule that's repeatedly repeated, perhaps ad nauseum, is that the work must be done in a workmanlike manner. We first encounter this in Article 110, and it seems like we're reminded about 96 more times in the Code. But most of those repetitions include additional material specific to the type of application.
Note that I'm not disparaging the NEC for all this repetition. I'm disparaging the sloppy installers and cheap owners who make it necessary. Qualified contractors who take pride in their work and do it right often must compete on price with people who really do not know what they are doing and whose work is disgraceful. With the mechanical execution of work requirement being so explicit and so ubiquitous throughout the NEC, qualified contractors can have more authority when explaining why the job must be done this way and why it costs a little more to get it right.
- You must remove the accessible portions of abandoned cables [830.25]. If cables are left in place for future use, the identification tag must be durable enough to withstand the environment.
- As with any other cable installation, when you install these cables in a hollow spaces, ducts, etc., you must do so in a way that does not substantially increase the possible spread of fire or products of combustion [830.26]. The use of firestops is one sure way to meet this requirement.
- The requirements for cables that are outside but entering buildings are in Part II.
- Where practicable, locate these broadband cables below any electric light or power conductors [830.44(A)(1)] when installing on poles or in-span.
- When passing these broadband cables above roofs, leave 8 feet of vertical clearance [830.44(B)]. Why so much, when there is so little power on these cables? It's not about an electrocution risk, it's about giving people room to work on the roof without ducking under the cables. You'll find a dizzying array of clearances listed in 830.44; find the one(s) that apply to your installation.
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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