During wall construction, the reserved hole shall be about 20mm larger than the length and width of the distribution box. But with some simple math and planning (don't worry, we'll walk through it!), you can design a system that works smoothly even when you're running all the gadgets. The calculations must take into account the volume of the box as well as the volume of any extensions such as domed covers or extension rings. Part (B), “Box Fill Calculations,” describes the method for. Load capacity calculation: Determine the total power demand of industrial facilities, including continuous load (such as production lines, pumps) and intermittent load (such as maintenance equipment, temporary workstations), and calculate the rated current required for each power distribution box. Enter wire count, gauge (AWG), and conduit entries to get the correct electrical box size for safe installations. This is because accurately determining the size of main panels and load center ensures they can safely and. The electrical box volume calculation determines the minimum required size of an electrical box based on the number and size of conductors and devices it will contain. This ensures compliance with electrical codes and prevents overcrowding.