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Thread: Classified Locations (Pierced Walls)

  1. #1
    Join Date
    Jul 2010

    Classified Locations (Pierced Walls)

    NFPA 497A indicates that an area that is separated from a Class 1 Div 1 area by a "pierced wall" will have a Class 1 Div 2 rating up to a certain point. It also indicates that if it were separated by an "unpierced wall", the area would be general purpose. I have a compressor room that will have a 2" air line running through a firewall into a Class 1 Div 1 area. Since it is a firewall, it will have fire-stop installed around the line where it penetrates the wall. Is there anything that says that, since the penetration is sealed and there is no open hole between the two areas, that the compressor room can remain general purpose, or does it have to be Class 1 Div 2? Thank you!

  2. #2
    Join Date
    Apr 2004
    Mission Viejo, CA
    NFPA 497A has been discontinued for over 25 years. It has been replaced several times since then. It is not now and never was ANSI sanctioned. The most recent NFPA 497 is.

    That said, if the wall has been returned to its required fire rating, including the space around the penetration, the Division 1 location is limited to the classified side.

    I'm curious, what the compressor is compressing though. Compressors are notorious for creating classified locations on their own.
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

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