What is the conduit capacity for two cables based on the provided formula?

The correct formulation for conduit capacity, particularly when considering the maximum fill percentage for cables, is essential for ensuring safe and effective cable installations. The maximum fill percentages determine how many cables can fit within a conduit without causing overheating or other issues due to overcrowding.

In this context, the option indicating 31% fill capacity is specifically tailored for scenarios involving two cables. This 31% value derives from the National Electrical Code (NEC) guidelines establishing that when you have multiple conductors, such as two cables in a conduit, the total fill should not exceed a certain percentage of the conduit’s total cross-sectional area.

The formula presented, with the square root expression and the adjustment for the fill percentage (0.31), suggests that the volume occupied by the cables needs to be calculated, hence involving both cable diameters in the formula. This clearly indicates how to evaluate the minimum required diameter for the conduit to safely accommodate the two cables while adhering to acceptable fill parameters.

Overall, understanding this capacity is crucial for professional practice in AV systems installation to maintain regulatory compliance and ensure system reliability.