300.22(C) is the code section in the NEC.
It does matter who is asking for the equipment, if it's in Chicago their 300.22 is way different from the NECs.
This is Chicago's.
(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 (a) and (b) of this section. 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 the following:
(a) Conductors or cables installed in electrical metallic tubing with gland nut type fittings, intermediate metal conduit or galvanized rigid
(b) Type MI Cable as permitted in Article 330;
(c) Type MC Cable employing a smooth or corrugated impervious metal sheath without an overall nonmetallic covering, as permitted in
(d) Flexible metallic tubing as permitted in Article 349;
(e) Liquidtight flexible metal conduit in lengths not to exceed 6 ft (1.83 m), to connect physically adjustable equipment and devices, other
than lighting fixtures, permitted to be in these spaces.
(2) Equipment. Electric equipment with a metal enclosure and no direct openings to the air space, and associated wiring material
suitable for the ambient temperature shall be permitted to be installed in such other space unless prohibited elsewhere in this chapter. Boxes
shall have no holes and shall be provided with gasketed covers.
FPN: This requirement is not intended to limit recessed fixtures that are constructed with tight seams and joints. Where so constructed
no additional gasketing or sealing is required.
Exception: Integral fan systems specifically identified for such use.
(d) Information Technology Equipment. Electric wiring in air-handling areas beneath raised floors for information technology
equipment shall be permitted in accordance with Section 18-27-300.22(c) and Article 645.
[This message has been edited by russ m (edited 06-23-2003).]