In what situation does Table 310.17 apply?

Table 310.17 is specifically applicable to insulated conductors that are carried in free air. This table provides important guidelines for determining the allowable ampacities of conductors based on various factors, including environmental conditions such as whether conductors are in free air, which allows for natural cooling.

When conductors are installed in free air, they are capable of dissipating heat more effectively than when enclosed in a raceway or cable jacket. The table takes into account factors such as temperature and the presence of other conductors in proximity, which helps ensure that these conductors can operate safely without overheating.

In contrast, the other scenarios, such as conductors in a raceway, enclosed by cable jackets, or under high voltage conditions, rely on different tables or guidelines that address their specific requirements for safety and performance. Thus, the conditions outlined in Table 310.17 are tailored uniquely for insulated conductors when they are exposed in the open environment, making option B the appropriate answer.