An insulated grounded conductor of a system is required to be identified by all of the following methods except?

The correct identification of an insulated grounded conductor is critical for ensuring safety and proper electrical system installation. The methods of identification involve specific color codes that help in recognizing the wires and their functions. In this context, the use of white and blue insulation is accepted for identifying a grounded conductor.

White insulation is commonly used for grounded conductors, particularly in the United States, allowing for clear identification and reducing the risk of accidental contact with live wires. Blue insulation is also recognized, depending on codes, for certain applications or specific types of grounded conductors.

In contrast, red insulation is typically used for ungrounded conductors in various types of systems, indicating that it may carry voltage and should be treated accordingly. Green insulation, meanwhile, signifies a ground wire, which is specifically meant for grounding conductors and not for identifying a grounded conductor in the same way as white or blue. Because of this distinction, green insulation should not be used to identify an insulated grounded conductor.

Therefore, the identification method that is not appropriate for an insulated grounded conductor is represented by the green insulation, because it serves a different purpose in electrical systems.