What should be prevented from entering service raceways or equipment regarding service-entrance and overhead service conductors?

Water should be prevented from entering service raceways or equipment because it poses a significant risk of electrical hazards. When water comes into contact with electrical conductors or circuitry, it can lead to shorts, corrosion, and even electrical shock hazards. This is especially critical in service-entrance areas where high-voltage conductors are present. Water intrusion can compromise the integrity of the electrical system and increase the likelihood of failure or fire.

In contrast, while dust and air may also be undesirable in certain contexts, they do not present the same level of immediate danger that water does in terms of electrical safety. Therefore, the focus on preventing water from entering protects both the equipment and the safety of individuals who may interact with the electrical system.