Which one of the following electrical ducts is suitable for an underground installation or embedded in concrete?

  1. Rigid metal conduit (RMC)
  2. Intermediate metal conduit (IMC)
  3. Rigid PVC conduit
  4. Other raceways round in cross section and suitable for use underground or embedded in concrete
  5. All of the above

Answer: E

The 2011 NEC includes a new definition for "electrical duct." As noted in 310.2, electrical duct is defined as "Electrical conduits, or other raceways round in cross section, that are suitable for use underground or embedded in concrete."

Owen is the owner and president of National Code Seminars and the holder of master electrician certifications in 46 states. He can be reached at necexpert@aol.com.