What is the ampacity of a 14 AWG THW copper conductor connected to a motor marked with design letter B?

To determine the ampacity of a 14 AWG THW copper conductor connected to a motor marked with design letter B, it's important to reference the National Electrical Code (NEC) guidelines. The NEC defines the ampacity for conductors based on their gauge, type, and the specific application they are used for.

For a 14 AWG copper conductor in a typical setting, the standard ampacity in terms of continuous service is generally considered to be 15 A under normal conditions. However, when a motor is involved, the situation is a bit different due to the starting current requirements of motors and the designation letter.

Design letter B motors have a specific starting and running current characteristic. The marking of design letter B indicates a higher allowable starting current compared to some other design types, allowing for a slightly higher rated ampacity of the conductor. Thus, when dealing with a 14 AWG conductor connected to a motor with this designation, it is accepted in the electrical industry that the conductor can safely carry up to 20 A.

Consequently, 20 A is appropriate for the specific conditions associated with a motor marked as design letter B, allowing for the necessary current flow without overheating and ensuring safe operation. This takes into account the nature of the