Through-wall lighting assemblies and wet, dry or no niche luminaires must be connected to an insulated copper equipment grounding conductor sized according to 250.122, but no smaller than what AWG?

• A. 10 AWG
• B. 14 AWG
• C. 6 AWG
• D. 12 AWG

Answer: (D)

The key idea is how the equipment grounding conductor size is determined. The NEC specifies the size of the grounding conductor based on the overcurrent device protecting the circuit (250.122), giving a minimum size for many circuits. But for certain lighting fixtures—specifically through-wall lighting assemblies and wet, dry, or no niche luminaires—the code sets a higher minimum than the bare minimum you’d see for general lighting. In these cases, the grounding path must be robust enough for environments that are moisture-prone or physically exposed, so the insulated copper equipment grounding conductor cannot be smaller than 12 AWG. That’s why 12 AWG is the correct minimum. While conductors larger than 12 AWG (like 10 AWG) would also meet the requirement, 12 AWG is the smallest size permitted for these fixture types. Smaller options such as 14 AWG would not satisfy this particular installation rule.