Which type of cable is specified when identifying the maximum number of conductors in a box?

The type of cable that is relevant when identifying the maximum number of conductors in a box is THWN-2. This designation refers to a type of thermoplastic electrical wire that is both heat- and moisture-resistant, making it suitable for wet locations as specified by NEC guidelines. When calculating the allowable number of conductors in a box, THWN-2 is important because it provides the necessary characteristics for heat dissipation and compliance with box fill calculations as outlined in the NEC.

The NEC provides specific derating factors based on the type of cable insulation used and its application, which can impact how many conductors can safely fit in a single enclosure without exceeding temperature limits. Given that THWN-2 can be used in a wider variety of conditions compared to some of the other cable options, it is appropriate for determining conductor capacity in boxes.

Other types of cables like THHN, Romex, and UF each have their specific applications and limitations. THHN is not rated for wet locations, which may limit its use in certain conditions, while Romex is a type of non-metallic sheathed cable that has its own unique guidelines regarding conductor count. UF (Underground Feeder) is designed for buried applications but does not have the same wide acceptance