Understanding NEC Article 384: Strut-Type Channel Raceways

Introduction

NEC Article 384 outlines the specifications and installation guidelines for strut-type channel raceways. These raceways, constructed from durable materials like steel, stainless steel, or aluminum, provide mechanical support and pathways for electrical conductors in various environments. Their versatility makes them suitable for industrial, commercial, and hazardous applications.

Scope

This article covers the permitted uses, prohibited applications, and construction specifications of strut-type channel raceways. It ensures safety, reliability, and compliance in power distribution systems, particularly in exposed or dry locations.

Key Features

1. Material and Construction:
   • Fabricated from steel, stainless steel, or aluminum.
   • Designed to enable mechanical and electrical continuity, with corrosion protection through galvanizing or organic coatings.
2. Applications:
   • Ideal for exposed work, power poles, and extensions through walls, partitions, and floors.
   • Suitable for hazardous locations as specified in NEC Chapter 5.
3. Accessibility:
   • Removable covers allow easy access for installation and maintenance.

Permitted and Prohibited Uses

Permitted Uses:

1. Exposed Installations:
   • Raceways can be surface-mounted or suspended.
2. Dry Locations:
   • Approved for indoor use in non-corrosive environments.
3. Corrosive Locations:
   • Allowed when protected with appropriate finishes.
4. Hazardous Locations:
   • Usable as specified in NEC Chapter 5.

Prohibited Uses:

1. Concealed Locations:
   • Not allowed unless closures are removable, and the raceway within walls remains covered.
2. Severe Corrosive Influences:
   • Ferrous raceways with enamel protection alone are not permitted.

Installation Guidelines

1. Conductor Size and Number:
   • Conductors must not exceed the size for which the raceway is listed.
   • The total cross-sectional area of conductors must not exceed 20% of the raceway’s interior area.
2. Securing and Supporting:
   • Surface-mounted raceways must be secured at intervals no greater than 10 feet.
   • Suspended raceways must also follow these support intervals.
3. Splices and Taps:
   • Allowed within raceways with accessible covers.
   • Conductors, including splices and taps, must not fill more than 75% of the raceway’s interior at any point.
4. Grounding:
   • Strut-type channel raceways can serve as equipment grounding conductors if bonded per 250.118(A)(13).
   • Snap-fit metal covers are not permitted as the sole means for electrical continuity.

Construction Specifications

1. Design and Compatibility:
   • Accessories like elbows, couplings, and fittings must mechanically and electrically couple without damaging conductors.
2. Corrosion Protection:
   • Steel components require protective coatings, such as galvanizing or enamel, to resist environmental damage.
3. Marking Requirements:
   • All raceway sections must be marked for identification per 110.21(A).

Applications

1. Industrial Settings:
   • Common in factories and warehouses for robust power distribution.
2. Commercial Spaces:
   • Used in exposed work and for supporting luminaires and electrical equipment.
3. Hazardous Locations:
   • Provides safe pathways for wiring in classified areas, as outlined in NEC Chapter 5.

Compliance Tips

1. Ensure Proper Protection:
   • Select raceways with appropriate finishes for corrosive environments.
2. Follow Fill Limits:
   • Avoid overfilling raceways to maintain efficiency and safety.
3. Regular Inspections:
   • Periodic checks ensure mechanical integrity and electrical continuity.

Conclusion

NEC Article 384 provides essential guidelines for safely installing and using strut-type channel raceways. By adhering to these standards, electricians and engineers can ensure the reliability, safety, and efficiency of electrical systems across various applications.