Cable Tray

Cable tray is a system used to support and route electrical cables, communication cables, and other types of wiring in both commercial and industrial environments. It provides a safe, organized, and efficient way to manage cables, ensuring they are accessible, protected, and properly supported. A well-designed cable tray system can significantly enhance the durability and longevity of your wiring infrastructure.

Key Features of Cable Trays:

Choosing the right cable tray can have a profound impact on your project’s success and efficiency. There are several factors to consider, including the type of cables it will support, the environment where it will be installed, and the future scalability of your wiring system.

Types of Cable Trays

• Ladder Tray: Has two parallel rails with rungs in between, resembling a ladder. It allows for good ventilation, which is helpful in dissipating heat.
• Trough Tray: Enclosed on three sides, providing more protection to cables. The open side makes it easy to add or remove cables.
• Solid Bottom Tray: Completely enclosed, offering maximum protection to cables, preventing dust and debris from entering the tray.
• Channel Tray: Smaller and typically used for light-duty applications or in situations where fewer cables need to be routed.
• Wire Mesh Cable Tray: Made of welded wire mesh, this type of tray is lightweight and provides easy installation and flexibility for routing cables. It is commonly used in industrial or commercial settings where space is constrained and flexibility is key. Offers more ventilation than solid trays, which helps reduce heat buildup, but still provides protection from physical damage.
• Bridge or Raceway: These systems are a variation of the cable tray, designed for long-distance runs or where multiple trays need to be connected to form a continuous route. They are often used for connecting cable trays over large areas.
• Single Rail or Channel: A simpler design compared to the traditional ladder tray, this version uses one side rail with cross members (or no rungs at all). It is often used for low-capacity installations or for smaller cable runs.

When selecting materials for your cable tray, it’s essential to consider the specific needs of your project. For instance, in environments exposed to moisture, a corrosion-resistant cable tray made of fiberglass or galvanized steel might be necessary.

Materials

• Steel: The most common material, offering strength and durability. Often galvanized for corrosion resistance.
• Aluminum: Lighter than steel and resistant to corrosion, but not as strong.
• Fiberglass: Used in corrosive environments, such as in chemical plants, where resistance to moisture or chemicals is needed.

The width and depth of your cable tray are crucial for accommodating various types of cables and ensuring sufficient airflow to prevent overheating.

Cable Tray Sizing Considerations

Tray Width

The tray width should be sufficient to accommodate the cables, with extra room for future expansion. It’s generally a good practice to keep about 30–40% of the tray’s total capacity free for future cable additions.

Tray Depth:

The depth of the tray depends on the cable type and weight. Deeper trays are often required for larger cables or for installations that need to support heavier loads, such as power distribution cables.

Cable Fill Ratio:

The fill ratio is a percentage that indicates how much of the tray’s volume is occupied by cables. According to the National Electrical Code (NEC), a typical fill ratio should not exceed 50%–60% of the tray’s total volume, which allows for proper air circulation and easy maintenance.

Proper installation of cable tray supports and fittings is vital for maintaining the integrity of the system. Ensure your installation complies with local electrical codes and standards.

Load Rating:

The tray must be able to support the weight of the cables it will carry. The load rating is usually specified by the manufacturer, and it’s important to adhere to these ratings to prevent sagging or failure of the tray system.

Cable Tray Supports and Fittings:

Cable trays need to be properly supported and equipped with additional fittings to ensure they are secure and functional:

Supports:

• Mounting brackets, hangers, or clamps are used to secure the cable tray to ceilings, walls, or floors. These must be spaced at intervals as specified by the manufacturer or code to prevent sagging and to maintain the integrity of the system.
• The spacing is typically between 5 to 10 feet, depending on the tray’s design and load.

Fittings:

• Elbows: Used to change the direction of the cable tray (e.g., for turning corners).
• Tees: Used for branching off the tray system to multiple routes.
• Reducers: Transition between trays of different sizes.
• End Caps: To close off open ends of a cable tray for a neat finish.
• Crosses and Splice Plates: Used to join multiple sections of trays or to create complex routing configurations.
• Wire Mesh Fittings: For wire mesh trays, fittings like elbows, tees, and couplings help maintain the system’s integrity while allowing flexible routing.

Safety and Code Compliance:

Cable trays need to comply with local electrical codes and safety standards. These include:

• National Electrical Code (NEC): In the U.S., the NEC provides guidelines for cable tray installations, particularly around fill capacity, grounding, and cable separation.
• Grounding and Bonding:
  • Cable trays themselves need to be grounded to reduce the risk of electrical shock or fire. This is especially important in areas where flammable materials are present.
  • Conductive trays, such as those made of metal, should be properly bonded to the ground system.
• Separation of Cables:
  • NEC also specifies that power cables and communication cables (data, voice, etc.) should be separated to reduce the risk of electromagnetic interference (EMI). There are specific requirements for the minimum distances between these types of cables.
• Fire Safety:
  • In some regions, fireproof cable trays or those with fire-resistant coatings must be used in certain environments, such as in high-rise buildings or hazardous areas.

In high-risk environments, choosing an explosion-proof cable tray can provide additional safety and peace of mind against potential hazards.

Cable Tray Installation Considerations:

Planning the Pathway

Before installing a cable tray, the pathway should be carefully planned to ensure cables won’t be obstructed by walls, beams, or other structures. The tray should also allow for easy access and future expansion.

Clearance

Sufficient clearance must be maintained between the cable tray and any obstructions (e.g., walls, ceilings) to ensure proper ventilation and avoid heat buildup.

Cable Installation:

Specialized cable tray systems are available for specific applications, such as corrosive environments or areas requiring high flexibility.

• Cables should be laid in trays without sharp bends. Bends that exceed the manufacturer’s recommended radius can damage cables.
• Cables should be laid with enough slack to avoid stress or tension, especially at junctions or where connections are made.

Maintenance:

• Cable trays make maintenance easier, as cables are organized and accessible. Routine inspections should be conducted to check for any wear, sagging, or potential hazards like overheating.
• Properly labeling cables within the tray can also help when troubleshooting or making modifications.

Specialized Tray Systems:

In certain applications, you may require specialized tray systems:

Corrosion-Resistant Trays

For use in environments with high humidity, chemicals, or saltwater, trays made from non-corrosive materials such as fiberglass-reinforced plastic (FRP) or galvanized steel are ideal.

Explosion-Proof Trays

In industries where explosive gases or vapors are present, explosion-proof cable trays are used. These trays are designed to prevent sparks from igniting the surrounding environment.

Flexible Cable Trays

In areas with complex pathways or limited space, flexible trays can be used to navigate tight corners or irregular routes.

Cost Considerations:

Initial Investment

For optimal results, consult with a professional to ensure that your cable tray installation meets all necessary requirements and is tailored to your project’s needs.

The cost of cable trays can vary widely depending on material, size, and complexity. Galvanized steel trays are typically more cost-effective, while fiberglass trays may be more expensive due to their corrosion resistance.

Maintenance Costs

The ease of access for maintenance and upgrades helps reduce long-term costs. A well-maintained cable tray system can last decades with minimal need for repairs.

Installation Labor

Proper installation is essential for ensuring that the system functions efficiently and complies with safety codes. Labor costs can vary based on the complexity of the installation.

Believe Industry have a full range of roll forming machines for cable tray, cable tray ladder, strut channel, etc. Contact us now for more information.