Which of the following is not considered a flexible type of raceway?

Intermediate Metal Conduit (IMC) is not considered a flexible type of raceway. IMC is a rigid conduit made of steel that provides physical protection and support to electrical conductors. Its design and manufacturing process give it a sturdy, inflexible structure, making it suitable for environments where a durable, long-lasting raceway is required.

In contrast, flexible types of raceway, such as flexible PVC, flexible metal conduit, and liquid-tight flexible non-metallic conduit, are designed to accommodate movement and bending, which allows for easier installation in tight or irregular spaces. These types of raceway can be manipulated to navigate around obstacles and can be more forgiving in environments where vibration and movement may occur. Thus, while IMC offers high strength and protection, it lacks the flexibility characteristic of the other listed options.