Type NM-B (Non-Metallic Sheathed Cable): Often called by the popular brand name “ Romex,” NM-B is the most common cable used for interior wiring in modern homes. Understanding the difference between white vs yellow electrical wire is essential for safe and accurate electrical wiring. In high-voltage residential wiring (120-volt and 240-volt circuits), a yellow wire is designated as a secondary hot conductor, meaning it is energized and carries current. The. Electrical wire and electrical cable are a means of electrical connectivity between switches, outlets, appliances, and more.