According to NFPA 70, which statement regarding underground cable and conductors is true?

The correct statement is that insulated conductors and cables must be listed for use in wet locations. This requirement is critical because underground installations are subject to moisture and environmental factors that can affect the safety and performance of electrical systems. Conductors that are approved for wet locations are specifically designed to withstand these conditions without degrading or posing hazards such as electrical shock or short circuits.

In the context of NFPA 70, or the National Electrical Code (NEC), the guidelines specify that when installing conductors underground, they must have appropriate ratings to ensure safety and reliability. This includes being resistant to moisture, which is why the listing for wet locations is imperative for underground applications.

Other options do not reflect the necessary safety standards. Insulated conductors and cables that are unlisted do not meet the regulatory requirements and may pose safety risks; therefore, they cannot be assumed compliant for underground use. Additionally, listing for dry locations would not address the unique challenges posed by underground environments where moisture is present. The option suggesting that all underground cables are automatically approved for use disregards the stringent standards set forth to ensure electrical safety and performance in various environments.