Multiple cable trays in one span

Multiple cable trays can be installed in a single span if the support spacing, tray strength, and splice placement are properly designed according to standards.

Key Considerations

Support Span and Tray Strength When installing multiple cable trays in one span, the distance between supports is critical, as tray strength decreases exponentially with longer spans. Each tray must be rated for the combined load of all cables it will carry, and the support span should be chosen to minimize deflection and stress. For best performance, the recommended support location is 1/4 of the span, which reduces stress at splice points and maintains structural integrity (Eaton B-Line series guidance), . Splice Plate Placement Only one splice plate should be placed between supports. This ensures that the trays remain structurally sound and electrically grounded. Matching tray lengths to the support span helps control splice locations and simplifies installation . Tray Alignment and Load Distribution When multiple trays are installed side by side, ensure that loads are evenly distributed across all trays. Using heavy-duty expansion splice plates or adjustable vertical splice plates can help accommodate slight misalignments and thermal expansion, preventing undue stress on any single tray . Standards Compliance Installations must comply with NEMA VE-1 and VE-2, which define load/span classes and support requirements, as well as the NEC (NFPA 70) and CEC for safe electrical installation. These standards cover metal and nonmetallic trays, ladder, channel, and wire mesh types, ensuring that multi-tray spans meet safety and performance requirements . Practical Tips

• Use sufficiently strong support brackets capable of handling the combined weight of multiple trays.
• Maintain consistent tray spacing to prevent cable sag or interference.
• Consider environmental factors such as wind, snow, or vibration, which may affect long spans .
• For long outdoor spans, extra-long supports can reduce the number of expensive supports while maintaining safety . By carefully designing the support spacing, selecting appropriate tray types, and following splice and load guidelines, multiple cable trays can be safely installed in a single span while maintaining compliance with electrical and mechanical standards.