What color is not permitted for insulation on ungrounded conductors?

The use of color-coding for insulation on electrical conductors is critical for safety and identification purposes. In accordance with the National Electrical Code (NEC) and other related standards, the color white is typically used for grounded conductors, which means it should not be used for ungrounded conductors.

Grounded conductors, such as neutral wires, are designated to safely carry current away to the ground, while ungrounded conductors carry the live current. When a white insulated wire is mistakenly used for ungrounded conductors, it can lead to confusion, mis-wiring, and potential electrical hazards, as someone might assume it is a neutral conduct rather than a live one.

In contrast, colors like red and black are widely accepted for ungrounded conductors, as they clearly indicate that these wires carry live voltage and should be treated with caution. Gray is also generally used for grounded conductors, but it’s important to be aware of how local codes may interpret it in specific contexts. However, since white is reserved for grounded conductors, its use for ungrounded conductors is not permitted, which is why the choice is considered correct.