Under which condition can 4 AWG and larger conductors of a basic color other than green be used as an equipment grounding conductor?

Using 4 AWG and larger conductors of a basic color other than green as equipment grounding conductors is permitted only when there is clear identification that distinguishes the conductor's grounding function. The identification must encircle the conductor, which provides unmistakable visual cues to anyone working with or around the electrical system. This marking is essential in ensuring safety and compliance with code requirements.

By encircling the conductor, it is immediately recognizable as a grounding conductor, aiding in preventing any accidental misuse or disconnection. Proper identification is crucial in an electrical system to ensure that all personnel, including those performing maintenance or troubleshooting, can safely identify the grounding conductors amidst other circuits.

Other conditions mentioned, such as the presence of ground monitors or the installation in a separately derived system, do not grant permission for using these conductors as grounding unless they are properly marked. The assurance of safety and clarity in electrical systems heavily relies on appropriate color coding and identification standards that help mitigate risks associated with electrical faults.