The calculation sums the cross-sectional areas of all cables including their outer sheaths and checks against the maximum fill area for the selected tray type. Calculate individual cable areas — Determine the overall outside diameter of each cable including insulation and jacket. Follow these simple steps: Define Tray Dimensions: Enter the width and depth of your planned cable tray (in mm or inches). Select Fill Standard: Choose 40% for power cables (NEC compliant) or 50% for. How cable tray fill differs from conduit fill, which NEC table applies to your tray type, and how to run the math before you pull a single cable. Worked example for a typical industrial routing.
