Which of the following is NOT a material used to construct rigid metal conduit?

PVC, or polyvinyl chloride, is a type of plastic that is commonly used in the electrical industry, offering lightweight and non-corrosive properties for various applications. However, it is not classified as a rigid metal conduit. Rigid metal conduits are specifically made from metals that provide durability and protection against physical damage and environmental stresses typically associated with electrical installations.

The other materials listed—red brass, stainless steel, and aluminum—are all metals recognized for their structural integrity and strength, making them suitable for constructing rigid metal conduit. Each of these offers specific benefits, such as corrosion resistance or weight considerations, but they all share the characteristic of being metals, which aligns with the definition of rigid metal conduit.