Where the grounded conductor for a service carries no load, what is the minimum size required?

The minimum size required for a grounded conductor in a service that carries no load aligns with the specifications found in Table 250.102(C)(1) of the National Electrical Code (NEC).

This table outlines the minimum size requirements for grounded conductors based on the size of the ungrounded conductors. It ensures proper grounding for safety and compliance with regulatory standards, even when not carrying current. This is crucial for maintaining safety in electrical installations and preventing potential hazards such as electric shock or fire.

The other choices do not directly specify the minimum size for grounded conductors in the context described by the question. Specifically, referring to Section 220.61 pertains more to calculations for branch circuits based on anticipated loads rather than the sizing of grounded conductors when there is no load. Likewise, the ungrounded service conductors refer to conductors that are not grounded and their sizes do not determine the minimum size for the grounded conductor, which serves a different functional purpose in the system.