Which table may only be used for 120/240-volt, 3 wire, residential single-phase service-entrance conductors?

The correct answer is based on the specific context of the National Electrical Code (NEC) and its relevant tables for determining conductor sizes based on various service conditions. Table 310.15(B) specifically addresses the allowable ampacities of conductors based on their insulation type and installation conditions.

In the context of 120/240-volt, 3-wire residential single-phase service-entrance conductors, this table provides the necessary information for selecting the appropriate size of conductors that can safely handle the electrical load for residential applications. The factors considered in the table include temperature ratings, conductor material (copper or aluminum), and installation specifics that are commonly associated with residential service entrances. This is crucial for ensuring safety and compliance with electrical codes.

Other options reference different areas of the NEC. For instance, Table 250.66 pertains to the size of grounding conductors for various sizes of the largest ungrounded conductors, while Table 400.22 relates to the ampacity of flexible cords. Table 240.4 deals with overcurrent protection for conductors and does not specifically address the requirements of service-entrance conductors. Therefore, when focusing on the parameters for 120/240-volt, 3-wire residential service