What is the maximum amperage permitted for No. 1 THW wire?

• A. 100 amps
• B. 110 amps
• C. 130 amps
• D. 150 amps

Answer: (C)

The maximum amperage permitted for No. 1 THW wire is based on the National Electrical Code (NEC) and the ampacity tables that specify the maximum current that different wire sizes can handle based on their insulation type and installation conditions. THW, or thermoplastic heat and water-resistant wire, has specific ratings depending on factors such as the ambient temperature and the number of conductors in a raceway.

For No. 1 THW wire, the correct maximum allowable amperage is established as 130 amps under standard conditions. This rating accounts for safe operation without overheating the conductor, ensuring that the wire can conduct electricity efficiently without risk of damage or fire hazards.

Understanding these ratings is crucial for electrical contractors, as it helps them choose the appropriate wire size for various applications while staying compliant with electrical codes and safety standards. Adjustments may be necessary if the wiring is in certain environments or configurations that affect the wire's ability to dissipate heat, but the base ampacity for No. 1 THW wire is correctly identified as 130 amps.