This step‑by‑step approach helps you determine width, depth, support spacing, and allowable load with confidence. Plan 20–30% spare capacity for growth. Select Fill Standard: Choose 40% for power cables (NEC compliant) or 50% for. Cable tray support quantity can be calculated using a simple formula: Support Quantity = Total Length ÷ Support Spacing + 1 20 ÷ 2 + 1 = 11 supports In a typical project, a 20-meter cable tray with 2-meter spacing requires 11 supports. Cable tray supports are components used to fix and support. In this guide, you will learn how to calculate cable tray size step by step using a practical formula, tray selection rules, and a real example. 9 (B), when using ventilated tray with multi conductor control cable, the sum of the cross sectional areas shall not exceed 50 percent of the interior cross section of the cable raceway / tray. Unlike a simple wire trough, which is typically a covered channel for shorter runs, cable trays provide a comprehensive support system for complex wiring paths over long. Hubbell Wiring Device-Kellems and Hubbell Premise Wiring are divisions of Hubbell Incorporated, a U. headquartered manufacturer with over 130 years of supplying solutions for the electrical and data markets. Hubbell's strength is demonstrated by a long-standing reputation for supplying reliable.