National Electrical Code Tips: Article 840, Premises-Powered Broadband Systems

1. Article 840 is the last Article in the NEC (as of the 2023 Code). It is not the last place to find valuable information. Past this point in the NEC you'll find useful tables and annexes.
   
2. The Scope of Article 840 has expanded and contracted over the past few Code cycles. Now the Scope is the same as the title of the Article. Much simpler that way.
   
3. Part I contains principles/requirements that are found elsewhere in the NEC repeatedly, except here you get referred to other places to read them: 1. Mechanical execution of work needs to be neat and workmanlike [820.24]; Abandoned cables have to be labeled as such [840.25]; and 3. You can't substantially increase the spread of fire [840.26].
   
4. Part II is titled "Cables Outside and Entering Buildings". It's been greatly edited down into almost nothing. It basically says to bury cables at least six inches deep.
   
5. Part III provides protection requirements. None of which are actually stated here.
   
6. Depending upon what you are protecting, you will apply 770.93, 820.93, or 805.93 (and 805.90).
   
7. Part IV contains the "grounding" requirements. Much of this is done by referring to other requirements. That makes sense for consistency of application, but following all these text jumps can be confusing. If you're going to do a project covered by Article 840, look up all of the "grounding" (it's typically bonding, instead) requirements and write them down in one place. Alternatively, you can just note that if it's metallic it needs to be bonded to the equipment bonding jumper and that includes any driven ground rods. Do not drive a ground rod for this system and let it float relative to other ground rods; that creates a dangerous difference of potential.
   
8. Part IV does exclude two types of applications from grounding requirements. Communications circuits don't have to be grounded [840.101(B)] and the network terminal doesn't have to be grounded unless its listing requires it to be grounded [840.101(C)].
   
9. Part V was eliminated with the 2023 revision. It provided requirements for installation methods within buildings. Part V was extremely short, and consisted of 840.133 which was not much and just told you to apply the requirements of 770.133.
   
10. The communications cables can carry power wiring, too [Part VI]. The text here had been extensively revised with the 2020 NEC but is barely changed with the 2023 revision.