Understanding NEC Article 324: Flat Conductor Cable (Type FCC)

Introduction

NEC Article 324 provides guidance for the design, installation, and use of Flat Conductor Cable (Type FCC). This field-installed wiring system is designed for low-profile applications, particularly under carpet squares, offering flexibility, accessibility, and space efficiency. Type FCC systems are frequently used in office environments and other controlled spaces, where conventional wiring methods may be impractical.

Scope

This article covers branch circuit wiring systems incorporating Type FCC cables and associated accessories. These systems are limited to 300 volts between ungrounded conductors and 150 volts between ungrounded and grounded conductors, with branch circuits rated up to 20 amperes for general use and 30 amperes for individual circuits.

Key Features of Type FCC Systems

1. Construction:
   • Type FCC cable comprises three to five flat copper conductors, one of which serves as an equipment grounding conductor.
   • Encased in top and bottom shields for mechanical protection and electrical grounding.
2. Floor Coverings:
   • Carpet squares must be no larger than 1 meter by 1 meter and adhered with release-type adhesives for easy access.
3. Shielding:
   • Includes metal top shields for floor protection and optional non-metallic bottom shields.
4. Markings:
   • Conductors are clearly marked for identification, including material type, ampacity, and maximum temperature rating.

Permitted and Prohibited Uses

Permitted Uses:

1. General-purpose and appliance branch circuits.
2. Floors made of concrete, ceramic, wood, or similar materials.
3. Damp locations and heated floors, provided materials are rated for the environment.

Prohibited Uses:

1. Outdoors or in wet environments.
2. Corrosive or hazardous locations.
3. Residential, school, or hospital buildings, except for administrative office areas.

Installation Requirements

1. Securing and Supporting:
   • Components must be anchored to floors or walls using approved adhesives or mechanical systems.
2. Crossings:
   • No more than two Type FCC cables may cross at any point. Metal shielding must separate communication or signal cables.
3. Connections:
   • All connections must maintain electrical continuity, proper polarization, and sealing against dampness or liquid spillage.
4. Grounding and Bonding:
   • All metal components, including shields and boxes, must be electrically continuous with the equipment grounding conductor.
5. Splices and Taps:
   • Modifications are allowed with approved connectors, provided all unused cable ends are insulated.

Applications

1. Office Environments:
   • Power delivery for workstations and lighting systems under modular carpeting.
2. Commercial Buildings:
   • Ideal for low-profile installations in administrative spaces.
3. Renovation Projects:
   • Replaces outdated wiring systems with minimal disruption.

Compliance and Safety Tips

1. Use Approved Accessories:
   • Ensure all fittings, connectors, and shields are listed for Type FCC systems.
2. Monitor Damp Locations:
   • Use moisture-resistant materials and seal openings to maintain system integrity.
3. Routine Inspections:
   • Periodically check for wear, corrosion, and secure grounding connections.

Conclusion

NEC Article 324 ensures the safe and effective use of Flat Conductor Cable (Type FCC) systems. By adhering to these guidelines, electricians can implement low-profile, accessible, and efficient wiring solutions tailored to specific applications while maintaining safety and compliance.