Understanding NEC Article 322: Flat Cable Assemblies (Type FC)

Introduction

NEC Article 322 outlines the requirements for the installation, use, and construction of flat cable assemblies (Type FC). These specialized cables, characterized by their flat, compact design, are used for branch circuits in controlled environments. Type FC cables are valued for their efficient use of space and suitability for specific applications like lighting and small power loads. This article ensures safety, reliability, and proper usage of Type FC cable systems.

Scope

Article 322 applies to flat cable assemblies operating at a maximum voltage of 300 volts to ground and used in systems with branch circuits rated up to 30 amperes. It covers the construction, permitted and prohibited uses, securing and supporting requirements, splicing, tapping, and the necessary marking of these assemblies.

Key Features of Type FC Cable

• Construction: Composed of two to five parallel 10 AWG special stranded copper conductors, integrally formed with an insulating web material.
• Markings: The cable is labeled with critical information, such as its voltage rating, temperature rating, conductor size, and manufacturer identification. This ensures proper application and compliance.
• Raceways and Fittings: Designed for use with specific surface metal raceways and fittings identified for compatibility.

Permitted and Prohibited Uses

Uses Permitted

Type FC cables are allowed for:

1. Branch Circuits: Supplying lighting, small appliances, or small power loads.
2. Exposed Work: Installed in areas where they remain visible and accessible.
3. Protected Installations: Where installed less than 8 feet above the floor or fixed working platforms, they must be protected by a cover identified for such use.
4. Surface Metal Raceways: Must be used within identified raceway systems installed before pulling the cable assemblies.

Uses Not Permitted

Type FC cables cannot be used:

1. In Corrosive Conditions: Unless specifically rated for the environment.
2. In Hoistways, Elevators, or Escalators: These locations require specialized wiring methods.
3. In Hazardous Locations: Unless explicitly allowed by other NEC provisions.
4. Outdoors or in Wet/Damp Locations: Unless identified for such applications.

Installation Requirements

1. Securing and Supporting:
   • Cables must be supported by their design features within surface metal raceways.
   • Raceways must be installed as complete systems before pulling the cables.
2. Boxes and Fittings:
   • Dead Ends: Terminate flat cable assemblies in end-cap devices identified for use.
   • Luminaire Hangers: Use fittings designed for compatibility with Type FC assemblies.
   • Extensions: All extensions must use approved wiring methods within listed junction boxes.
3. Splices and Taps:
   • Splices: Must occur in listed junction boxes.
   • Taps: Use devices rated between 15 and 30 amperes, with markings to indicate their suitability.

Construction and Marking Requirements

1. Conductor Identification:
   • Grounded conductors must be identified by a white or gray marking throughout their length.
   • Terminal blocks must feature color-coded sections (white, black, red, and blue) for clarity and safety.
2. Temperature Ratings:
   • Clearly marked on the cable’s surface at intervals of 24 inches or less to ensure compatibility with the operating environment.
3. Insulation:
   • Cables must use materials recognized in NEC Table 310.4(1), suitable for general branch-circuit wiring.

Applications

1. Commercial Buildings:
   • Efficient wiring for lighting systems in offices and retail spaces.
2. Residential Settings:
   • Space-saving solutions for small power loads in apartments or single-family homes.
3. Specialized Installations:
   • Ideal for compact wiring needs where surface metal raceways provide additional protection.

Best Practices for Compliance

1. Proper Installation:
   • Ensure raceways are fully installed before pulling cables.
2. Use Compatible Components:
   • Select fittings and accessories explicitly identified for Type FC cables.
3. Routine Inspections:
   • Inspect for wear, damage, or non-compliance during routine maintenance.

Conclusion

NEC Article 322 establishes clear guidelines for the safe and effective use of flat cable assemblies (Type FC). By adhering to these requirements, electricians and engineers can achieve compact, efficient, and reliable wiring systems tailored to specific environments. Understanding the permitted uses, installation standards, and construction requirements ensures compliance and enhances system performance.