Journeyman Electrician Practice Exam 2025 – 400 Free Practice Questions to Pass the Exam

Ampacity refers to the maximum amount of electric current a conductor or device can carry before sustaining immediate or progressive deterioration. For a size 3 AWG THHN copper conductor, the ampacity can be determined based on several factors, including insulation type, temperature rating, and installation conditions.

When assessing the ampacity of a 3 AWG copper conductor, the general standards set by the National Electrical Code (NEC) and other regulatory bodies indicate that under normal conditions—specifically referencing a 75°C (167°F) insulation rating—3 AWG copper tends to have an ampacity of approximately 85.0 amperes. This rating assumes typical installation practices and does not account for derating factors that might apply in specific scenarios such as high ambient temperatures or bundling of wires.

Hence, the correct choice reflects this standard for ampacity, acknowledging the specific parameters and conditions under which such a conductor would operate efficiently and safely.