NM cable is commonly used in dry, inside-wall installations because

• A. It is economical for dry, inside-wall installations
• B. It provides the highest fault current protection
• C. It is preferred for exposed outdoor use without rating
• D. It is suitable for wet locations without protection

Answer: (A)

NM cable is chosen for dry interior spaces mainly because it is inexpensive and easy to install in inside-wall runs. Its plastic jacket and conductors are designed for dry locations, not for moisture, wet locations, or exposure to the elements. When used inside walls where it’s protected from moisture and physical damage, NM provides a cost-effective wiring method that meets typical residential needs. For outdoor, damp, or wet locations, or exposed areas, different conductors or methods (such as outdoor-rated cable or conduit) are required, which adds cost and complexity compared to NM used in appropriate dry interior spaces.