Which color should NOT be used for marking positive PV system DC circuit conductors?

In the context of photovoltaic (PV) systems, the National Electrical Code (NEC) provides guidelines for color coding of conductors to help identify their purpose and avoid dangerous mistakes. For positive DC circuit conductors in a PV system, the commonly accepted color scheme dictates that certain colors are designated for specific functions.

Green is widely recognized as the color for grounding conductors. Using it for positive DC circuit conductors could lead to significant confusion and potentially unsafe situations, as it might suggest that the conductor is intended for grounding rather than carrying current. This is why using green for marking positive conductors is not permitted.

In contrast, colors like yellow, black, or blue are acceptable for identifying positive DC circuit conductors in various configurations. Each of these colors has its own designated use, but they do not interfere with the standard color coding for grounding. This careful designation of colors helps ensure safety and functionality in electrical systems.