According to NEC 110.14(C)(1)(a)(2), what column of Table 310.16 is used for the ampacity of a 75°C conductor with devices marked 60°C?

The National Electrical Code (NEC) provides specific guidelines on how to determine the ampacity of conductors based on their temperature rating and the rating of terminals or devices they are connected to. In this case, we are looking at a conductor rated for 75°C, but it is connected to devices that are marked for use at 60°C.

According to NEC 110.14(C)(1)(a)(2), when a conductor is rated higher than the device it connects to, the ampacity must be determined based on the rating of the device rather than the rating of the conductor. This means that in scenarios where the conductors exceed the temperature rating of the connected devices, you have to refer to the lower rating of the device (in this case, 60°C) to find the appropriate ampacity.

Therefore, for a conductor rated at 75°C that is connected to terminals rated for 60°C, you would look up the ampacity using the column in Table 310.16 that corresponds to the 60°C rating. This ensures that the conductor is not overloaded beyond the safe operating temperature of the devices, thus preventing potential overheating and hazards.

Using the 60°C ampacity provides a safe and code-compliant approach