How to handle cable tray openings

Cable tray openings should be properly finished, protected, and treated to prevent cable damage, corrosion, and safety hazards.

Edge Protection and Finishing

Openings in cable trays, such as cut ends, elbows, tees, or expansion joints, must be smoothed and deburred to prevent the cable sheath from being cut during installation or maintenance. On-site modifications should be polished, and anti-rust paint or protective coatings should be applied to exposed metal edges to prevent corrosion and maintain structural integrity .

Surface Treatments

Cable trays are exposed to environmental factors like moisture, chemicals, and temperature fluctuations. To enhance durability and corrosion resistance, the following surface treatments are commonly used :

• Hot-dip galvanization: Immersing trays in molten zinc to form a robust zinc-iron alloy coating, ideal for industrial or outdoor environments.
• Electro-galvanization: Thin zinc coating via electrolysis, suitable for less aggressive environments.
• Painting: Epoxy or other chemical-resistant paints protect against corrosion and allow color customization.
• Powder coating: Environmentally friendly, durable, and aesthetically consistent.
• Anodizing: For aluminum trays, creating a dense oxide layer that improves hardness, UV resistance, and longevity outdoors.

Expansion Joints and Openings

For long cable runs, expansion joints must be incorporated to accommodate thermal expansion and contraction. Openings at these joints should be treated to prevent mechanical stress on cables and maintain electrical continuity . Flexible copper jumpers are recommended to bridge metallic trays across joints, ensuring proper grounding and safety.

Compliance and Safety

Openings must comply with NEC Article 392 and other local standards. Key considerations include:

• Maintaining proper clearances for installation and maintenance.
• Ensuring metallic trays are grounded to prevent electrification hazards.
• Avoiding sharp edges or burrs that could damage cables or compromise insulation.
• Using finished elbows and tees rather than forcing modifications on-site .

Summary

Proper treatment of cable tray openings involves smoothing edges, applying protective coatings, incorporating expansion joints, and ensuring grounding. These measures prevent cable damage, corrosion, and electrical hazards while extending the lifespan of the tray system and maintaining compliance with safety standards .