What is the minimum calculated dimension for "height" in inches for a pull box when considering various conduit sizes?

The minimum calculated dimension for the "height" of a pull box, as specified in the National Electrical Code (NEC), takes into account the size and number of conduits entering and exiting the box. The dimension of 18.5 inches is established to ensure there is adequate space to manage wiring and connections safely and efficiently.

This height accommodates the necessary working space for electrical conductors, allowing for ease of installation, maintenance, and future modifications of the wiring. It also ensures that there is sufficient clearance to prevent damage to cables and facilitate safe access during electrical work.

In contrast, the other options either do not meet the minimum height requirements or exceed them unnecessarily for typical installations, potentially leading to inefficient use of space or increased costs. Thus, the height of 18.5 inches is both a practical and code-compliant choice for a pull box.