Communications Circuits

Article 805 covers communications circuits — traditional telephone wiring and the twisted-pair data cabling (like Category structured cabling) that dominates modern buildings. It draws its common rules from Article 800 and adds the specifics for this circuit type: where a primary protector is required, entrance cable, and the listing types (CM, CMR, CMP, CMX) matched to plenum, riser, and general locations.

A big modern driver here is powered communications cable — Power over Ethernet. As PoE pushes more current down data cable to feed cameras, access points, and lights, the article added attention to conductor heating in large cable bundles, so data cable carrying real power doesn't cook itself in a tray. Between protection at the entrance and thermal limits in the bundle, 805 is where everyday network cabling meets electrical safety.

When it applies

Article 805 covers communications circuits, the telephone and data cabling, the twisted pair and structured wiring, that carries voice and network signals into and around a building. It sets how those cables enter, get protected against surges, get grounded, and stay separated from power wiring so the two systems do not interfere or create a hazard.

Common mistakes

• Skipping the primary protector and bonding at the point where the outside cable enters.
• Running communications cable in the same bundle or box as power without the required separation.
• Using cable not rated for a plenum or riser where the pathway demands it.

In the field

At the entrance I bond the communications ground back to the building's grounding electrode system, the same one the power service uses. Separate grounds sitting at different potentials are what let a surge find its way through the data gear.