The first place to start is by understanding what a Dry, Damp, and Wet location actually is. The National Electrical Code®[NEC®] addresses each of these items in Article 100.
Location, Dry. A location not normally subject to dampness or wetness. A location classified as dry may be temporarily subject to dampness or wetness, as in the case of a building under construction.
Location, Damp. Locations protected from weather and not subject to saturation with water or other liquids but subject to moderate degrees of moisture.
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.
Once you have established the location where the NM-B Cable is going to be located, you then have to examine it even closer. Many people believe that NM-B Cable installed in liquidtight flexible nonmetallic conduit [LFNC] outside abovegrade is acceptable simply because it is installed in liquidtight. However, that would be incorrect based on Section 300.9 of the NEC which states "Raceways in Wet Locations Abovegrade. Where raceways are installed in wet locations abovegrade, the interior of these raceways shall be considered to be a wet location. " and lets never forget that Section 300.5(B) says when installing underground "The interior of enclosures or raceways installed underground shall be considered to be a wet location."
NEC Section 334.10(A)(1) specifically permits NM Cable in both exposed and concealed work in normally dry locations it's actually Section 334.12(B)(4) that states NM Cable is not permitted in Wet or Damp location.
At the end of the day the AHJ will have to make the final call. However, with the guidance of Article 100, Section 300.9, and Article 334 we are confident the reader of this article will make the Right Call !
