What must be true of nonmetallic raceways and cables exposed to sunlight?

Nonmetallic raceways and cables that are exposed to sunlight must be listed or identified as suitable for such use. This requirement is emphasized in the National Electrical Code (NEC) to ensure safety and reliability. Nonmetallic materials can degrade when exposed to direct sunlight due to ultraviolet (UV) radiation, which can lead to insulation failure and increased risk of electrical hazards.

For raceways and cables to be deemed appropriate for outdoor use, manufacturers typically undergo testing and certification processes to ensure that their products can withstand such environmental stresses without compromising their integrity. Thus, the proper identification or listing of these products confirms that they meet the necessary standards for UV resistance and durability, making it crucial for compliance with safety regulations.

The other options do not accurately reflect the NEC requirements for nonmetallic raceways and cables regarding sunlight exposure. For instance, while painting can offer some level of protection, it is not a requirement. Likewise, being underground is not a condition that applies to all nonmetallic installations, and waterproof specifications pertain to different aspects not exclusively related to sunlight exposure.