Understanding NEC Article 805: Communications Circuits

NEC Article 805 focuses on the installation and protection of communications circuits and equipment. These systems form the backbone of communication networks in residential, commercial, and industrial settings, supporting voice, video, and data transmission.

Scope of Article 805

This article applies to:

• Communications circuits and equipment.
• Requirements previously found in Article 800 that are now specific to communications circuits.

Exclusions: Article 805 does not cover the internal wiring of information technology equipment systems, which is addressed in Article 645​.

Key Requirements for Communications Circuits

1. General Installation (805.18)
   • Equipment connected to a communications network must be listed according to 800.171.
   • Test equipment used temporarily for installation, maintenance, or repair by qualified personnel is exempt from this requirement​.
2. Wiring Entering Buildings (805.50)
   • Communications wires and cables must meet insulation and separation requirements:
     • Underground Installations: Insulation requirements may be waived for certain configurations.
     • On Buildings: Separation of at least 4 inches is required from power conductors unless specific conditions are met.
     • Inside Buildings: Wires entering a building must pass through noncombustible bushings or metal raceways to prevent fire hazards​.
3. Primary and Secondary Protection (805.90)
   • Circuits exposed to over 300 volts or lightning must include a listed primary protector.
   • Secondary protectors, if used, must be listed and connected downstream from the primary protector to limit currents​.
4. Grounding and Bonding (805.93)
   • Metallic sheaths of cables entering or terminating outside buildings must be grounded, bonded, or interrupted near the point of entry to prevent hazardous voltages.
   • Grounding and bonding must align with 800.100 requirements​.

Specific Applications

1. Cable Substitutions (805.154)
   • Substitution of listed cable types is allowed based on Table 805.154, which outlines hierarchy and fire-resistance standards.
2. Communications Outlets in Dwellings (805.156)
   • New residential constructions require at least one communication outlet, cabled to the service provider demarcation point.
   • This facilitates connectivity for devices like fire detection and security systems​.

Applications

Article 805 supports communication systems in:

• Residential Buildings: Voice and data connectivity for homes.
• Commercial Facilities: Office communication networks and centralized systems.
• Industrial Environments: Control and signaling systems requiring robust communication infrastructure.

Conclusion

NEC Article 805 provides essential guidelines for installing and protecting communications circuits, addressing wiring, protection, grounding, and cable substitutions. Adherence to these standards ensures reliable and safe operation across diverse communication applications.