A THHN conductor will have 75°C termination on one end and a 60/75°C termination on the other, which ampacity column will be used?

• A. 60°C column
• B. None of these
• C. 90°C column
• D. 75°C column

Answer: (D)

Conductor with 75 °C temperature rating must have ampacity from the 60°C column or the 75°C column.
It is permissible to use the 75°C rating if the installed conductor is rated at least 75 °C.
Because all of the connection points in this example have at least a 75°C rating, the conductor’s ampacity can be based on the 75°C column