What is the permitted cross-sectional area fill for a 4" x 4" metal wireway?

To determine the permitted cross-sectional area fill for a 4" x 4" metal wireway, it is important to consider the maximum fill capacities that are typically dictated by electrical code regulations. The dimensions provided indicate that the wireway has a cross-sectional area of 16 square inches (4 inches by 4 inches).

When applying the permissible fill ratios dictated by the National Electric Code (NEC) or similar regulations, generally, a maximum fill is applied that is often limited to 50% for wires where the total conductors exceed three individual wires. Therefore, half of the cross-sectional area would be calculated as 8 square inches.

However, for specific configurations and based on established guidelines, the most common permissible fill for wires in such a conduit system allows for around 3.2 square inches of actual conductors. This figure comes from considerations of spacing, heat dissipation, and wire insulation requirements to ensure safety and compliance with established electrical practices.

Thus, the 3.2 square inches correctly reflects a safe and compliant cross-sectional area fill, conforming with industry standards for wiring in a metal wireway setup, making it the most appropriate choice.