Final answer:
Totally enclosed non-metallic raceways exposed to the sun must be marked as 'sunlight-resistant' or with equivalent wording to indicate they can withstand UV light deterioration.
Step-by-step explanation:
The question pertains to the identification and labeling requirements for totally enclosed non-metallic raceways (often referred to as conduit) that are installed in places where they are exposed to the direct rays of the sun. In such cases, these raceways need to be marked with the designation 'sunlight-resistant' or equivalent wording to indicate that they are suitable for such use. This marking helps ensure that the material used for the raceway is capable of withstanding the deteriorating effects of ultraviolet light over time.
This requirement is because non-metallic materials can degrade when exposed to UV light, leading to brittleness and reduced functional integrity. Therefore, to prevent damage and preserve the safety and reliability of the electrical system, sunlight-resistant markings are necessary on raceways in these environments.