What is the minimum size the grounded conductor shall be according to specified standards?

The minimum size for the grounded conductor, as specified in the National Electrical Code (NEC), ensures that it is adequately sized to safely handle fault current and provide effective grounding. According to Table 250.102(C)(1), the sizing of the grounded conductor is determined based on the size of the phase conductors and their corresponding requirements, which can vary depending on the application.

Choosing 1/0 AWG as the minimum size reflects the necessity to maintain a balance between performance and safety. A grounded conductor that is too small may not effectively carry fault currents, potentially resulting in overheating or failure to trip circuit protection devices efficiently. The 1/0 AWG size provides a reliable measure to ensure safe operation in typical residential and commercial electrical installations.

While the other options suggest various sizes, they do not meet the established minimum requirement based on the grounding practices defined within the Code, leading to a specification that could create safety hazards. It's important to follow the standards set in Article 250 to ensure the electrical system is both functional and safe.