Q. What are the limitations on the use of rigid nonmetallic conduit in an underground application serving a gasoline dispenser?

A. Rigid nonmetallic conduit can be installed underground below a Class I location if the raceway is covered with not less than 2 feet of earth, concrete, or asphalt [514.8, Exception 2]. However, threaded rigid metal or threaded intermediate metal conduit must be used for the last 2 feet of the underground run.