Solid wiring ducts are best used when maximum cable protection is required or when the environment contains dust, debris, or contaminants. The bulleted list below compares these components and their. This article explains the three main types of wiring ducts—slotted, solid, and flexible, highlighting their structures, advantages, and typical applications. Engineers and facility managers face this critical decision daily, weighing upfront costs against long-term. Wiring ducts come in several types and each of them has been designed to meet specific needs: Solid wall wiring ducts are characterized by a smooth, solid construction. Variations in distribution feeder methods can affect many things, including design and cost.