Which material is commonly used for underground raceways due to its resistance to moisture?

PVC (polyvinyl chloride) is commonly used for underground raceways primarily because of its excellent resistance to moisture. This property makes it ideal for protecting electrical wiring and other components from the detrimental effects of water, soil, and other environmental factors typically found underground. PVC is non-corrosive, lightweight, and easy to install, which further enhances its suitability for this application.

In contrast, steel and copper are metals that, while strong and durable, can rust or corrode when exposed to moisture unless properly coated or treated. Fiber optic materials also do not share the same level of moisture resistance as PVC and are more sensitive to installation conditions and environments. Thus, the unique properties of PVC make it the preferred choice for underground installations where moisture resistance is critical.