Electrical Craft Certification 3 Practice Test 2026 – Complete Exam Prep

Non-metallic sheathed cable, commonly referred to as NM cable or Romex, is the standard type of cable used for residential wiring. This cable consists of two or more insulated conductors, as well as a ground wire, all encased in a non-metallic sheath. NM cable is favored in residential applications because it is easy to work with, lightweight, and provides the necessary protection for the conductors while being flexible enough to navigate through walls and tight spaces.

This type of cable is suited for dry interior environments and is designed to be installed in a variety of residential applications, including powering outlets, lights, and appliances. Its compatibility with standard household voltage ratings (like 120/240 volts) and ease of installation contribute to its widespread use in homes. NM cable adheres to electrical codes, ensuring safety standards are met.

Other types of cables mentioned are typically used for different purposes. Coaxial cable is primarily used for TV and internet connections, twisted pair cable is commonly used in telecommunications and data networks, and fiber optic cable is utilized for high-speed data transmission, especially in long-distance applications. None of these alternatives are appropriate for general residential wiring, making non-metallic sheathed cable the correct choice for this context.