What is the minimum depth required for a hand hole enclosure containing four 350kcmil THWN conductors?

To determine the minimum depth required for a hand hole enclosure containing four 350kcmil THWN conductors, we consider the National Electrical Code (NEC) and guidelines surrounding conductors in enclosures. The specific requirement for hand hole enclosures involves ensuring sufficient space to accommodate the conductors and any necessary accessories while allowing for proper bend radius and heat dissipation.

The depth of 8 inches is typically deemed adequate because it provides enough room for the installation and maintenance of the conductors, as well as space for ensuring compliance with the minimum bending radius. Specifically, large conductors like 350kcmil require a larger bend radius to avoid damage, and the minimum depth helps facilitate this.

While 6 inches might be too shallow and not provide sufficient space, depths greater than 8 inches, such as 10 or 12 inches, can lead to unnecessary increases in material cost and installation complexity without providing additional benefits. Therefore, 8 inches is the minimum depth that satisfies safety codes and practical installation requirements for the specified conductors.