Which installation allows the use of Table 310.12(A)?

Table 310.12(A) is specifically used for determining the allowable ampacity of conductors used in residential applications. This table provides guidelines for sizing conductors based on their insulation type and various environmental factors, specifically for installations that fit certain conditions.

The situation described in the correct answer is a 120/208V, 150A feeder for an apartment unit. This scenario falls under the requirements set forth in Table 310.12(A), which applies to feeder conductors for individual living spaces. Apartment units typically draw loads that can be calculated using this table, as it accounts for the specific use of multi-family dwelling spaces.

For the other options, they are either not for individual living units or do not meet the specifications related to residential applications that Table 310.12(A) is meant for. Thus, they are not appropriate situations for the application of this table. This reinforces the context of understanding where and how to apply Table 310.12(A) in real-world electrical installations, particularly in residential settings.