What is the maximum amperage permitted for No. 8 THWN conductor?

What is the maximum amperage permitted for No. 8 THWN conductor?

• A. 30 amps
• B. 40 amps
• C. 50 amps
• D. 60 amps

Answer: (C)

The maximum allowable amperage for a No. 8 THWN (Thermoplastic Heat and Water Resistant Nylon-coated) conductor is based on the National Electrical Code (NEC) and its associated tables that outline the ampacity of conductors. For a No. 8 conductor, the maximum ampacity is typically 50 amps under certain conditions, which is in accordance with NEC Table 310.16.

In this context, the ampacity can vary depending on several factors, including the installation conditions, the type of insulation, and the ambient temperature. THWN conductors are designed for wet and dry locations and can handle high temperatures. When considering these factors, the specific ampacity for No. 8 THWN in standard conditions is most correctly identified as 50 amps. This makes it important for electrical contractors to refer to the appropriate tables and consider these variables when determining what amperage can safely be carried by this conductor size.