What is the amperage for #4 CU?

The correct answer is based on the ampacity of #4 copper (CU) wire, which is typically rated at around 151 amps for certain standard conditions, such as being used for a specific temperature rating, installation method, and conductor grouping. Ampacity refers to the maximum amount of electric current a conductor or device can carry before sustaining immediate or progressive deterioration.

In the case of #4 copper wire, this rating is often determined under typical residential wiring scenarios, where the wire is properly installed and has adequate ventilation for heat dissipation. It's essential to adhere to the National Electrical Code (NEC) guidelines, which provide the specific parameters for determining the ampacity based on various installation conditions.

The other options present significantly higher amperage ratings, which are not standard for #4 copper wire under typical conditions. These unusually high values may correspond to larger gauges or specific applications that would not apply in the context typically considered for general wiring tasks. Understanding the context of wire sizing and the importance of adhering to ampacity ratings is crucial for safety and compliance in electrical work.