Calculate horizontal, vertical, or compound cable tray offsets based on bend angle, offset distance, and available installation space. Calculate V-cut dimensions, bolt positions, slope length, and hanger spacing. SVG diagram for on-site marking. Measure this distance along the straight tray. Free cable tray fill calculator for electrical designers, plant electricians, and industrial maintenance teams who need to verify that cable installations comply with NEC Article 392 fill requirements. 0133 sq in each, the screen is about 0. NEC 392 Fill Rules by Tray Type 3. Step-by-Step Calculation Example 4. Common Mistakes to Avoid NEC 392.