When using three-wire Type NM cable the white insulated wire is sometimes used as a traveler conductor for three-way and four-way switching and is required to be reidentified as an ungrounded conductor.

Question

Quizplus · Accepted Answer

This is true according to the National Electrical Code (NEC). The white wire is typically used as a traveler for three-way and four-way switches, but since it is normally used as a grounded conductor (neutral), it must be reidentified as an ungrounded conductor (hot) by using black or red tape at each end to distinguish it from the grounded conductor.

When Using Three-Wire Type NM Cable the White Insulated Wire