What is the minimum gauge of copper wire that can be used in any branch circuit?

The minimum gauge of copper wire that can be used in any branch circuit according to the National Electrical Code (NEC) is number 14. This gauge is significant because it provides a balance between the ability to carry current safely and the need to minimize voltage drop over the circuit. For general residential applications, number 14 copper wire is rated for a maximum of 15 amps, making it suitable for various lighting and outlet circuits.

Choosing a wire gauge that is too small for the application could lead to overheating and potentially cause electrical fires, which is why understanding the specifications around wire gauge is crucial for safety and compliance with electrical codes. Other gauges like number 10, 12, and 16 have specific uses and ampacity ratings that may not make them suitable as the minimum wire gauge for all branch circuits. Thus, number 14 provides the required safety and performance for general usage in residential and light commercial applications.