Which identification is NOT acceptable for an insulated grounded conductor 6 AWG or smaller?

The identification of insulated grounded conductors is governed by the National Electrical Code (NEC) and industry standards to ensure safety and reduce the potential for confusion during installation and maintenance. For insulated grounded conductors that are 6 AWG or smaller, specific color coding is provided for clear identification.

A continuous red outer finish phased with white tape is not acceptable for identifying a grounded conductor. The use of red is typically reserved for phase conductors, which are conductors carrying current. The grounded conductor must be distinctly identifiable by specific colors defined in the regulations. A grounded conductor must be either a bare conductor, insulated with a white or gray outer finish, or marked with a continuous green outer finish.

The colors green and white are explicitly designated for use with grounding and grounded conductors. A green finish indicates a grounding conductor, while a white finish indicates a grounded conductor. Therefore, the other options presented adhere to the NEC's guidelines for the identification of grounded conductors and do not create confusion with phase conductors.

In essence, using red for a grounded conductor is contrary to established identification standards, making it an inappropriate option.