A Comprehensive Guide to Electrical Wire Management
Wireway is a vital component of electrical installations, designed to route, organize, and protect electrical wiring in industrial and commercial settings. It provides a structured pathway for conductors, preventing exposure to environmental hazards while ensuring safety and accessibility.
Proper wireway installation enhances system reliability, reduces downtime, and ensures compliance with regulatory standards such as NFPA 79, NEC 376.22, and NEC 310.15(B). In this article, we will explore the essential general requirements, fill capacity calculations, and best practices for implementing wireway in your electrical installation.
General Requirements for Wireway Installation
To maintain compliance, safety, and efficiency, wireway installations must adhere to the following general requirements:
1. Wireway Integrity and Grounding
- No wire ties are permitted within wireways to avoid insulation damage.
- Proper grounding is mandatory to provide an effective path to ground and prevent electrical faults.
- All conduit, wireways, and junction boxes must ensure a continuous path to ground.
2. Separation of Control and Power Wiring
- Wireway containing both control wiring and power wiring must be divided centrally using manufacturer-approved dividers.
- Separation helps prevent interference, signal distortion, and overheating.
3. Wireway Routing Best Practices
- Preferred Routing: A single wireway should be run along the entire length of the process skid or machine frame.
- Device Placement: Devices and wiring must be positioned above the lowest horizontal frame member to prevent exposure to mechanical damage or liquid ingress.
- Wireways must be installed in easily accessible locations for maintenance and troubleshooting.
4. Environmental Considerations
- Wireway must be suitable for the environment in which it is installed, including protection against:
- Corrosive chemicals
- Moisture & humidity
- High-temperature exposure
- IP54 (NEMA 12) construction is required for wireways used outside of an industrial control panel.
5. Wireway Load Capacity – Fill Percentage Guidelines
Wireway sizing and fill calculations must comply with industry standards:
A. On-Machine Wireway (NFPA 79)
- Maximum fill within a wireway shall be 50% of its interior cross-sectional area.
B. Off-Machine Wireway (NEC 376.22)
- Maximum fill within a metal wireway shall be 20%.
- Adjustment factors must comply with NEC 310.15(B)(2)(a) and NEC 310.15(B)(4).
Wireway Fill Calculation Example
To demonstrate proper wireway selection, let’s calculate the required wireway size for a given set of conductors.
Wire Types and Their Cross-Sectional Area:
| Wire Size | Type | Individual Area (in²) | Quantity | Total Area (in²) |
|---|---|---|---|---|
| 8 AWG | THHN | 0.0366 | 3 | 0.108 |
| 12 AWG | THHN | 0.0133 | 10 | 0.133 |
| 6 AWG | THWN | 0.0507 | 3 | 0.1521 |
Total Area Occupied by Conductors:
0.108+0.133+0.1521=0.3931 in²0.108 + 0.133 + 0.1521 = 0.3931 \text{ in²}0.108+0.133+0.1521=0.3931 in²
Minimum Wireway Area Required (Based on 20% Fill Rule)
0.39310.20=1.9655 in²\frac{0.3931}{0.20} = 1.9655 \text{ in²}0.200.3931=1.9655 in²
Recommended Wireway Size
A 4” x 4” wireway with 16 in² cross-sectional area will be sufficient since the utilized area is:0.393116=2.5% of the total available wireway space\frac{0.3931}{16} = 2.5\% \text{ of the total available wireway space}160.3931=2.5% of the total available wireway space
Additional Best Practices for Wireway Installation
To ensure a safe and efficient wireway setup, follow these best practices:
1. Accessibility and Safety
- Wireway covers must be removable for easy access and maintenance.
- Ensure smooth edges after cutting or trimming to prevent wire insulation damage.
2. Load and Equipment Placement
- Wireway should not be used as a mounting base for equipment such as solenoid valves.
- Wireway should not interfere with normal maintenance or machine operations.
3. Conduit & Junction Box Compliance
- Wireway systems should be coordinated with conduit runs for optimal wiring layout.
- Conduit and junction boxes must be installed to maintain a continuous grounding path.
Conclusion
Wireway plays a crucial role in protecting and organizing electrical wiring in industrial and commercial settings. By following NFPA 79, NEC 376.22, and NEC 310.15(B) guidelines, you can ensure compliance, efficiency, and safety in your electrical installations.
Key takeaways: ✅ Always ground wireway properly
✅ Follow fill percentage limits (50% On-Machine, 20% Off-Machine)
✅ Choose appropriate wireway materials based on environmental conditions
✅ Ensure accessibility for maintenance and future expansions
By implementing these best practices, you can optimize your electrical wiring system and improve operational reliability.
Would you like assistance in selecting the best wireway for your specific application? Contact us today for expert recommendations!