What is the minimum size copper wire that can be used on a 600 V system?

The correct answer is based on the National Electrical Code (NEC) requirements for copper conductors in a 600 V system. For general use, the minimum size copper wire typically allowed is 12 AWG. This size is necessary to ensure adequate current-carrying capacity, which is essential for safety and performance in electrical applications.

This size allows for sufficient conductivity and reduces the risk of overheating. In circuits where the potential current load is significant, it's critical to have a conductor that can handle the load without exceeding its temperature rating. Therefore, for most 600 V applications, using a 12 AWG copper wire is standard practice.

The other sizes mentioned, such as 14 AWG, 16 AWG, and 18 AWG, do not meet the minimum size requirements for safe operation at this voltage level. They would be inadequate for various electrical loads and could lead to overheating, increased resistance, and potential failure of the electrical system.