What is the minimum size THW branch-circuit conductor permitted for protection when the overcurrent protective device is rated at 50 A?

In determining the minimum size of a THW branch-circuit conductor when the overcurrent protective device is rated at 50 A, it is important to reference the National Electrical Code (NEC) guidelines. According to NEC Table 310.16, the ampacity of conductors is defined based on their size, insulation type, and installation conditions.

For a conductor rated for 50 A overcurrent protection, it is necessary to ensure that the selected conductor can safely handle the load without exceeding its rated capacity. An 8 AWG THW conductor is capable of carrying current safely at a temperature rating typical for the insulation used. In most installation conditions, the 8 AWG THW has an ampacity of 40 A, which is below the requirement for a 50 A protective device but is the minimum size allowed when taking into account the conditions and allowing for possible derating due to ambient temperatures or bundling.

Thus, the selection of an 8 AWG THW conductor aligns with the requirements for safe operation and compliance with NEC standards, making it the appropriate choice in this scenario. This answer recognizes the minimum requirements for conductor size in reference to the potential load capacity and protection.