Connection of cable joints inside cable trays

Cable joints inside cable trays should be securely connected using appropriate mechanical methods, properly grounded, and installed with consideration for thermal expansion to ensure safety and system stability.

Mechanical Connection Methods

Cable trays require strong and reliable connections to support the weight of cables and maintain system integrity. Common methods for connecting cable joints include splice plates, bolted connections, quick connect systems, fish plates, clamps, and welding. Splice plates are flat metal plates with pre-drilled holes that are bolted to the ends of two tray sections to join them in a straight line, providing stability and load-bearing capacity. Quick connect systems and clamps allow faster installation and flexibility for future modifications, while welded connections offer permanent strength for heavy-duty applications (Apex Tray) .

Grounding and Bonding

Proper grounding is essential for safety. Metallic cable trays can serve as the Equipment Grounding Conductor (EGC), but each tray section should be bonded using grounding clamps to ensure electrical continuity. If multi-conductor cables with individual EGCs are installed, these should also be bonded to the tray. For aluminum trays, insulated conductors are recommended to prevent electrolytic corrosion, and bonding connections should use tin or zinc-plated connectors. Steel trays have specific cross-sectional area requirements to function as EGCs depending on the circuit protection rating (IDC Online) .

Expansion and Thermal Considerations

Cable joints must accommodate thermal expansion and contraction. Expansion joints should be installed at calculated intervals based on tray material and expected temperature variations. Proper placement prevents misalignment, physical damage to cables, and structural stress on the tray system. Following NEC Section 300-7(b) and NEMA VE 1 guidelines ensures that expansion joints maintain system functionality and long-term reliability (Ganglong Fiberglass) .

Best Practices

• Ensure all tray connections are tight and aligned to prevent sagging or cable damage.
• Maintain proper spacing and support for cables to avoid exceeding bend radius limits.
• Use corrosion-resistant materials appropriate for the environment, such as stainless steel or aluminum with protective coatings.
• Follow local electrical codes and manufacturer guidelines for installation, grounding, and expansion joint placement.
• Regularly inspect connections for mechanical integrity and grounding continuity to ensure long-term performance. By combining secure mechanical connections, proper grounding, and expansion joint planning, cable joints inside trays can maintain safety, durability, and ease of maintenance over the system's lifetime.