11.4 Communication Systems (Article 800)
Key Takeaways
- Article 800 covers general requirements for communications systems; the former communications-circuits article was reorganized in the 2020 NEC, with the primary protector and grounding rules consolidated under 800.100.
- A listed primary protector is required at the communications cable entrance wherever the cable is exposed to lightning or accidental contact with power conductors (800.90 / 800.100).
- The primary protector grounding conductor must be ≥ 14 AWG copper, as short as practicable (≤ 20 ft in one- and two-family dwellings), and terminate at the intersystem bonding termination (IBT) or the building grounding electrode system per 250.94.
- 800.133 requires a 2 in. separation between communications cables and power conductors unless all conductors are in raceway or metal-sheathed cable; a ½ in. barrier separation is permitted in common enclosures.
- A separate communications ground rod must be bonded to the building power grounding electrode system with a minimum 6 AWG conductor (800.100(D)).
Scope and 2020 Reorganization
Article 800 in the 2020 NEC was restructured: the new Article 800 "General Requirements for Communications Systems" consolidates shared rules (listing, marking, grounding, separation) that previously were duplicated across the former communications-circuits article (now Article 805), CATV (Article 820), and network-powered broadband (Article 830). For the exam, the blueprint items still point to Article 800, and the key sections — 800.100 (cable and primary protector bonding and grounding), 800.133 (separation), and 800.24 (mechanical execution) — remain in Article 800.
Communications circuits include telephone, data networking (Ethernet), fiber optic (cross-referenced to Article 770), and coaxial cable (cross-referenced to Article 820). The hazards Article 800 addresses are (1) lightning surge entering on the outside cable, and (2) accidental contact between the outside communications cable and power conductors.
Primary Protector — 800.90 and 800.100
800.90 requires a listed primary protector on each communications circuit that is exposed to lightning or to accidental contact with power conductors. The protector is located as close as practicable to the point of entrance of the cable into the building. Unlisted outside cable may run inside the building up to 50 ft from the entrance before terminating in a protector or enclosure per 800.48.
800.100(A) — Grounding Conductor
The grounding conductor for the primary protector must be:
- Insulated copper or other corrosion-resistant material.
- Not smaller than 14 AWG.
- As short as practicable; for one- and two-family dwellings it shall not exceed 20 ft in length. If over 20 ft is unavoidable, a separate ground rod (≥ 5 ft long) must be installed and bonded to the building power grounding electrode system with a minimum 6 AWG conductor [800.100(D)].
- Run in as straight a line as practicable.
- Mechanically protected where subject to damage. If run in a metal raceway, both ends of the raceway must be bonded to the grounding conductor to avoid an inductive choke effect.
800.100(B) — Electrode Termination
The grounding conductor must terminate, in order of preference:
- The intersystem bonding termination (IBT) per 250.94 — the preferred point.
- If no IBT: the building grounding electrode system [250.50], interior metal water pipe within 5 ft of entrance [250.52(A)(1)], accessible means exterior to the building [250.94], metallic service raceway, service-equipment enclosure, or the grounding electrode conductor.
- If none of the above exists: an individual electrode per 250.52(A)(1)–(A)(4) or a ground rod not less than 5 ft long and ½ in. diameter.
Bonding of separate electrodes (800.100(D)): Where a separate ground rod is installed for communications, it must be bonded to the building power grounding electrode system with a minimum 6 AWG conductor. This bonding eliminates dangerous voltage differences between the two systems during a lightning surge.
Mechanical Execution — 800.24
800.24 requires communications cables to be securely supported by the building structure. Cables shall not be strapped to the exterior of raceways, pipes, or other conduit (Exception: a mast intended to support the aerial drop). Cables in exposed work shall be run parallel with structural members where practicable. In plenum spaces (environmental air-handling spaces above suspended ceilings per 300.22(C)), only plenum-listed communications cable (CMP or equivalent) may be run without raceway.
Separation from Power Conductors — 800.133
800.133(A) governs separation of communications cables from electric power and Class 1 conductors.
| Situation | Required separation |
|---|---|
| Communications and power in the same raceway, box, or enclosure | Prohibited unless separated by a permanent barrier or listed divider, or power conductors are introduced only to supply comm equipment and separated by ½ in. (13 mm) |
| Communications and power run parallel outside raceway | 2 in. (50 mm) minimum separation |
| Power conductors in a raceway, metal-sheathed cable (MC, AC), UF, or nonmetallic-sheathed cable | 2 in. separation not required (raceway/sheath provides isolation) |
| Communications cable in its own raceway | 2 in. separation not required |
| Separation from lightning conductors | 6 ft (800.53) where practicable |
800.133(B) prohibits communications cables from being strapped, taped, or attached to the exterior of any raceway as a means of support (Exception: aerial mast spans).
Communications Cable Listing — 800.113
Communications cables installed inside buildings must be listed. The listing categories:
- CMP — plenum (for use in environmental air spaces per 300.22(C))
- CMR — riser (vertical shafts per 300.21)
- CM — general purpose
- CMG — general purpose (limited-use)
- CMX — limited-use (residential, ≤ 10 ft exposed)
Grounding vs. Bonding — A Common Exam Trap
Grounding connects equipment to the earth (grounding electrode). Bonding connects two conductive objects to keep them at the same potential. Article 800 uses both: the primary protector is grounded to the building electrode system (800.100(B)), and a separate communications ground rod is bonded to the building power electrode system with a 6 AWG conductor (800.100(D)) to prevent a voltage difference between the two during a lightning event. The exam will ask which conductor bonds a separate communications electrode to the power system — the answer is 6 AWG, the same size that bonds water pipe electrodes and building steel to the service.
Coaxial Cable Cross-Reference (Article 820)
Community antenna television (CATV) coaxial cable is governed by Article 820, which parallels Article 800. The 820 grounding conductor must be 14 AWG minimum and terminate at the IBT. Coax shields must be grounded at the building entrance. 820.100 provides the coax-specific grounding rules; 820.133 mirrors the 800.133 separation rules. On the exam, a question about "coaxial cable grounding" should route you to Article 820, not Article 800.
Exam Scenarios
- Long comm grounding conductor: A 25 ft grounding conductor runs from the primary protector to the panel in a single-family dwelling. Per 800.100(A), this exceeds the 20 ft limit — a separate ground rod (≥ 5 ft) must be installed and bonded to the building electrode system with a 6 AWG.
- Trench with comm and power: A 120 V landscape lighting circuit and a data cable share a 24 in. trench. Communications separation from power underground is governed by 725.136(C) for Class 2/3 and 800.133 for comm; the 2 in. separation rule applies above grade and the 12 in. rule applies below grade.
- Cable strapped to EMT: A CATV cable is tape-wrapped along the outside of an EMT run. Per 800.133(B), this is prohibited — the cable cannot be strapped to the exterior of a raceway for support.
A communications primary protector is installed in a single-family dwelling. The grounding conductor from the protector to the building grounding electrode system is 25 ft long. Under 800.100, what is required?
A communications cable and a 120 V lighting circuit are run parallel in an exposed wall cavity. What is the minimum separation required by 800.133?