404.14 Location of Outlets
The unthreaded portion of piping outlets shall extend not less than l inch (25 mm) through finished ceilings and walls and where extending through floors or outdoor patios and slabs, shall not be less than 2 inches (51 mm) above them. The outlet fitting or piping shall be securely supported. Outlets shall not be placed behind doors. Outlets shall be located in the room or space where the appliance is installed.
Exception: Listed and labeled flush-mounted-type quick- disconnect devices and listed and labeled gas convenience outlets shall be installed in accordance with the manufacturer's installation instructions.