Conductors are considered outside a building when they are installed ______.

• A. On the exterior of the building
• B. Underground
• C. In a conduit outdoors
• D. Any of these

Answer: (D)

The key idea is location relative to the building envelope. Conductors are considered outside a building if they are not inside the structure, regardless of how they’re installed. That includes conductors on the exterior surface, buried underground, or run in a conduit outdoors. So all of these situations meet the definition of outside a building.

This matters because outdoor installations are subject to different NEC requirements for weatherproofing, enclosure rating, grounding, protection from physical damage, insulation, and cable routing. Knowing that a conductor is outside tells you which sections of the code apply and what precautions are required.