NEC 300.5 (B)

 
 

(B) Wet Locations.

The interior of enclosures or raceways installed underground shall be considered to be a wet location. Insulated conductors and cables installed in these enclosures or raceways in underground installations shall be listed for use in wet locations and shall comply with 310.8

(C). Any connections or splices in an underground installation shall be approved for wet locations.