In a run of conduit that is not permitted to exceed 40% fill, the number of conductors can be calculated based on what measure?

The correct answer is based on the concept of conductor area in relation to conduit fill calculations. In electrical installations, it is crucial to ensure that conduits are not overfilled with conductors to maintain proper airflow, heat dissipation, and prevent damage to the insulation of the conductors.

The calculation for determining how many conductors can fit within a conduit considers the total allowable fill percentage—in this scenario, not exceeding 40%. This value is derived from the cross-sectional area of the conductors being installed. By calculating the area of each conductor and multiplying it by the number of conductors, you can assess whether the total fill is within the permissible limits for that conduit size.

Using the conduit diameter alone wouldn't provide the necessary detail about how much space the conductors will occupy. Conduit length is irrelevant to fill calculations, as the fill percentage pertains to cross-sectional area rather than linear measurements. Similarly, the type of conductive material does not affect the fill calculation; rather, it is the size and area of the conductors that are most significant.

Thus, referring to conductor area is essential in determining the maximum number of conductors allowed in a conduit while adhering to the specified fill requirements.