(C) Other Space Used for Environmental Air. This section
applies to space used for environmental air-handling
purposes other than ducts and plenums as specified in
300.22(A) and (B). It does not include habitable rooms or
areas of buildings, the prime purpose of which is not air
handling.
FPN: The space over a hung ceiling used for environmental
air-handling purposes is an example of the type of other
space to which this section applies.
Exception: This section shall not apply to the joist or stud
spaces of dwelling units where the wiring passes through
such spaces perpendicular to the long dimension of such
spaces.
(1) Wiring Methods. The wiring methods for such other
space shall be limited to totally enclosed, nonventilated,
insulated busway having no provisions for plug-in connections,
Type MI cable, Type MC cable without an overall
nonmetallic covering, Type AC cable, or other factoryassembled
multiconductor control or power cable that is
specifically listed for the use, or listed prefabricated cable
assemblies of metallic manufactured wiring systems without
nonmetallic sheath. Other types of cables, conductors,
and raceways shall be permitted to be installed in electrical
metallic tubing, flexible metallic tubing, intermediate metal
conduit, rigid metal conduit without an overall nonmetallic
covering, flexible metal conduit, or, where accessible, surface
metal raceway or metal wireway with metal covers or
solid bottom metal cable tray with solid metal covers.
(2) Equipment. Electrical equipment with a metal enclosure,
or with a nonmetallic enclosure listed for the use and
having adequate fire-resistant and low-smoke-producing
characteristics, and associated wiring material suitable for
the ambient temperature shall be permitted to be installed
in such other space unless prohibited elsewhere in this
Code.
Exception: Integral fan systems shall be permitted where
specifically identified for such use.