• Code Quiz: Raceways in Wet Locations Abovegrade

    NEC rules for installing a THHN/THWN insulated conductor in a raceway
    Aug. 21, 2014

    When installing a THHN / THWN insulated conductor in a raceway that is located on the outside wall of a building or structure (wet location), the choice for the type of conductor insulation is permitted to be based on _____________.

    A. the use of THHN insulation rating, based on a dry location rating, as the inside of the raceway is considered to be a dry location. The installation shall also comply with  310.10(C).

    B. the use of THWN insulation rating, based on a wet location rating, as the inside of the raceway is considered to be a wet location. The installation shall also comply with  310.10(C).

    C. all of the applicable rules for a rooftop installation.

    D. the application adjustment factors for conductors installed in raceways located on the outside wall.

    Find the Answer

    Answer: B

    As outlined in Sec. 300.9 of the NEC, “Where raceways are installed in wet locations abovegrade, the interior of these raceways shall be considered to be a wet location.” A similar change was made in 300.38 in the 2014 NEC for installations above 1,000V nominal.

    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 [email protected].

    About the Author

    Steven Owen

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