Which trade size 1-1/4 raceway has the smallest cross-sectional area?

The schedule type of a raceway indicates its thickness and overall design, which in turn affects its cross-sectional area. In the case of schedule 40 PVC and schedule 80 PVC, schedule 80 has thicker walls than schedule 40, resulting in a smaller internal cross-sectional area. Therefore, for the same trade size of 1-1/4 inches, schedule 80 PVC has a smaller cross-sectional area than schedule 40 PVC.

Rigid Metal Conduit (RMC), while also being sturdy, typically has thicker walls than schedule 40 PVC, leading to a larger internal diameter. Electrical Metallic Tubing (EMT) has a different design focus and wall thickness that also results in a larger cross-sectional area compared to schedule 80 PVC.

In summary, schedule 80 PVC, with its thicker wall construction, provides a smaller internal area compared to other options like schedule 40 PVC, rigid metal conduit, and electrical metallic tubing when all are sized at 1-1/4 inches. This makes schedule 80 PVC the correct answer for having the smallest cross-sectional area in this context.