The minimum thickness for a cast aluminum box measuring 6" X 4" X 3.5" is:

For a cast aluminum box measuring 6" x 4" x 3.5", the minimum thickness of 3/32 inches is acceptable according to industry standards and guidelines. This thickness is important as it ensures structural integrity and durability of the box, allowing it to withstand both physical impacts and environmental factors, such as moisture or temperature variations, which are common in electrical applications.

Using a thickness of 3/32 inches strikes a balance between being robust enough to provide protection and lightweight enough for practical installation and handling. It's essential that equipment, especially electrical enclosures, adheres to these minimum standards to ensure safety and effectiveness in their intended applications. Adopting the proper thickness also helps in maintaining compliance with regulatory standards that govern electrical installations, enhancing safety for both the equipment and the users.

Additionally, the other thickness options, while they may seem sufficient, do not meet established industry recommendations for this specific application, thereby making 3/32 inches the most suitable choice.