Actual cable tray requirements can depend on cable type, voltage, tray type, ventilation, spacing, ampacity, and local electrical code. Use the calculator for estimating, then check the required standard for final sizing. This weight is always there once the cables are in. Big cables weigh more: Thicker cables with more conductors mean more material, so they are heavier. This comprehensive guide will take you through the parameters; there are tables included for various types of cables, cable diameters, and tray sizes to. Calculate cable tray capacity, fill ratio, width, height, or cable diameter from four known values using inches, feet, cm, or meters.