As instruções do dispositivo não têm posição para decidir o que a NEC diz ou não.
No entanto, as instruções do dispositivo podem e fazer , fazer declarações sobre como o próprio dispositivo pode ser usado. E estes têm a força da lei.
NEC 110.3(B) Installation and Use. Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.
As instruções que você cita são claramente deferidas para a NEC quanto à definição de "locais úmidos".
100.1
Location, Damp. Locations protected from weather and not subject to saturation with water or other liquids but subject to moderate degrees of moisture. Examples of such locations include partially protected locations under canopies, marquees, roofed open porches, and like locations, and interior locations subject to moderate degrees of moisture, such as some basements, some barns, and some cold-storage warehouses.
Location, Wet. Installations underground or in concrete slabs or masonry in direct contact with the earth; in locations subject to saturation with water or other liquids, such as vehicle washing areas; and in unprotected locations exposed to weather.