Understanding NEC Article 820: Community Antenna Television (CATV) and Radio Distribution Systems

NEC Article 820 provides the requirements for the installation and protection of coaxial cable systems used in community antenna television (CATV) and radio distribution systems. These systems transmit radio frequency signals for television, radio, and security camera applications.

Scope of Article 820

This article applies to:

• Coaxial cable distribution systems for CATV, closed-circuit television (CCTV), and radio receivers.
• Coaxial cable used for security camera systems and other communication devices.

Informational Notes:

• Article 820 installations may follow Article 830 wiring methods to support future upgrades to broadband systems.
• Coaxial cable systems delivering power to associated equipment must limit voltage to 60 volts with power-limiting characteristics​.

Key Requirements for CATV and Radio Distribution Systems

1. Power Limitations (820.15)
   • Coaxial cables may supply power to equipment within the distribution system.
   • Power to premises devices not intended for coaxial delivery must be blocked.
2. Grounding and Bonding (820.93, 820.100)
   • Coaxial cables entering or attached to a building must have their conductive shields grounded.
   • Grounding must occur as close as practicable to the point of entry or termination.
   • Grounding blocks help minimize potential differences between the CATV system and other metallic systems.
3. Hazardous Locations (820.93(D))
   • Primary protectors or grounding devices cannot be located in hazardous (classified) areas unless permitted by Articles 501, 502, or 503​.

Cable Installation Methods

1. Cable Substitution and Hierarchy (820.154)
   • Coaxial cables must comply with fire resistance and use standards outlined in Table 820.154.
   • Substitute cables must meet the same or greater safety and performance requirements, such as CATVP (plenum-rated cables) for use in air-handling spaces​.
2. Installation Within Buildings (820.154–820.170)
   • Plenum and riser-rated cables must be used in their respective areas to prevent fire spread.
   • Cables must be supported properly, with care to prevent damage or interference during building operations.
3. Outdoor and Underground Installations (820.44)
   • Coaxial cables must maintain safe clearances from electric light, power conductors, and grounded surfaces.
   • Underground installations must use listed materials and follow separation guidelines from power conductors to avoid electromagnetic interference.

Additional Considerations

1. Abandoned Cables (820.25)
   • Unused coaxial cables must be removed unless tagged and reserved for future use to reduce fire hazards.
2. Primary Protectors (820.93(C))
   • Protectors must be installed on all cables external to premises to safeguard against lightning and voltage surges.
   • These devices should be located near the cable entry point.

Applications

Article 820 supports CATV and radio systems in:

• Residential Areas: Delivering TV, internet, and radio signals.
• Commercial Facilities: CCTV and distributed antenna systems for large buildings.
• Industrial Locations: Security and radio communication systems.

Conclusion

NEC Article 820 provides essential guidelines for coaxial cable installations in CATV and radio distribution systems. By addressing grounding, fire safety, and proper installation practices, this article ensures both safety and functionality in communication networks.