Which method is used to protect wires installed underground?

The correct choice involves using insulation designed specifically for wet environments when protecting wires installed underground. This is crucial because underground installations face exposure to moisture and potential water ingress, which can lead to insulation deterioration, short circuits, and overall failure of the electrical system. Insulation that is rated for wet locations provides a higher level of protection against these environmental factors, ensuring that the electrical wiring remains safe and functional over time.

Using weather-resistant cables is beneficial for outdoor installations, but it may not adequately address the specific concerns posed by underground conditions. Basic insulation is insufficient for such environments where prolonged exposure to moisture can compromise performance. Running wires above ground might be a solution for certain situations, but it defeats the purpose of underground installation and exposes the wires to other hazards, such as physical damage from external sources. Therefore, the key is utilizing insulation designed for wet environments to ensure reliability and safety for underground installations.