What is the minimum trade size RMC permitted to be installed between two panelboards that are 5 feet apart?

The question relates to the installation of rigid metal conduit (RMC) between two panelboards, specifically focusing on the minimum trade size required for the conduit's installation over a distance of 5 feet.

The National Electrical Code (NEC) specifies particular guidelines regarding the trade sizes of conduit, which are based on factors like the type and number of conductors, and the required fill capacities. For a distance of 5 feet between two panelboards, it is essential to ensure that the selected conduit size can accommodate the necessary conductor count while maintaining a safe and compliant installation.

In this case, choosing a minimum trade size of 2 inches satisfies these requirements. A 2-inch RMC is adequate for a reasonable number of conductors and meets the necessary fill requirements as specified by the NEC. It also allows ease of installation and potential future upgrades or conductor additions without needing to replace the conduit.

Using a smaller size would risk exceeding conduit fill limitations, which could lead to overheating issues or hinder the installation of the conductors. Therefore, the minimum trade size of 2 inches is appropriate for this application.