Can a white conductor in a 12/2 with ground MC cable be marked with purple tape to be used for a traveler from a 3-way switch?

In this scenario, marking a white conductor with purple tape to indicate its use as a traveler from a 3-way switch is acceptable. The National Electrical Code (NEC) allows for the reidentification of conductors, including the white conductor, as long as they are clearly marked to prevent confusion. Purple tape serves as a means to identify the conductor for a specific purpose, such as signaling that it is being used as a traveler in a 3-way switch arrangement.

By marking the white conductor, it ensures that other electricians, technicians, or anyone working on the system in the future can easily understand its function, thereby promoting safety and clarity in electrical installations. Thus, the practice aligns with the NEC guidelines, which support the proper identification of conductors when their designated function differs from the standard conventions associated with color coding.