In these motor conductor sizing scenarios, terminations are rated at what temperature?

In these motor conductor sizing scenarios, terminations are rated at what temperature?

• A. 60°C
• B. 90°C
• C. 75°C
• D. 105°C

Answer: (C)

The main idea is that conductor sizing for motors is tied to the temperature rating of the terminations where the conductors connect. In practice, motor terminations (the motor terminals, controllers, and related connection points) are rated at 75°C. So you select the conductor size using the 75°C ampacity from the NEC tables, as long as the conductor insulation itself also supports 75°C. If termination equipment were rated higher (like 90°C), you could use the higher ampacity, but typical motor terminations are 75°C, making 75°C the standard choice.

The main idea is that conductor sizing for motors is tied to the temperature rating of the terminations where the conductors connect. In practice, motor terminations (the motor terminals, controllers, and related connection points) are rated at 75°C. So you select the conductor size using the 75°C ampacity from the NEC tables, as long as the conductor insulation itself also supports 75°C. If termination equipment were rated higher (like 90°C), you could use the higher ampacity, but typical motor terminations are 75°C, making 75°C the standard choice.