Properly sizing a cable tray requires calculating both the physical weight and the volumetric space. The total applied load must never exceed the tray's safe working load. Wire Mesh Cable Tray Fill Ratio = Cross section of cable / Cross section of tray According to NEC 392. You don't need a PhD—just a consistent method. This step‑by‑step approach helps you determine width, depth, support spacing, and allowable load with confidence. Group by power. Follow these steps to generate your accurate Bill of Materials (BOM) and engineering report: Step 1: Define System Specifications: Select your cable tray type (e., Ladder, Trough), material (Steel, Aluminum, FRP), and dimensions. We will cover why it matters, show you how to do the sums with real examples, and help you choose. The cable follows the shape of a parable and the horizontal support forces can be calculated as R1x = R2x = q L2 / (8 h) (1) where R1x = R2x = horizontal support forces (lb, N) (equal to midspan lowest point tension in cable) q = unit load (weight) on the cable (lb/ft, N/m) L = cable span (ft, m) h.
[PDF Version]