The provisions of Article 300 of NFPA 70 are adopted by reference with the following modification:
1. Revise section 300.5(D)(2) by adding the following sentence at the end:
"Conductors entering a building shall be protected at the point of entrance by rigid metal conduit or intermediate metal conduit."
2. Revise section 300.22 to read:
"Wiring in Ducts Not Used for Air-Handling, Fabricated Ducts for Environmental Air, Plenums, and Other Spaces for Environmental Air (Plenums). The provisions of this section apply to the installation and uses of electric wiring and equipment in ducts used for dust, loose stock, or vapor material; ducts specifically fabricated for environmental air; and other spaces used for environmental air (plenums).
Informational Note: See Article 424, Part VI, for duct heaters.
(A) Ducts for Dust, Loose Stock, or Vapor Removal. No wiring systems of any type shall be installed in ducts used to transport dust, loose stock, or flammable vapors. No wiring system of any type shall be installed in any duct, or shaft containing only such ducts, used for vapor removal or for ventilation of commercial-type cooking equipment.
(B) Ducts Specifically Fabricated for Environmental Air. Equipment, devices, and the wiring methods specified in this section shall be permitted within such ducts only if they are necessary for the direct action upon, or sensing of, the contained air. Where equipment or devices are installed and illumination is necessary to facilitate maintenance and repair, enclosed gasketed-type luminaires shall be required.
In ducts specifically fabricated to for environmental air, only the wiring methods consisting of the following shall be permitted:
(1) Conductors or cables installed in electrical metallic tubing with gland nut type fittings, intermediate metal conduit or galvanized rigid metal conduit
(2) Type MI Cable as permitted in Article 332
(3) Type MC Cable employing a smooth or corrugated impervious metal sheath without an overall nonmetallic covering, as permitted in Article 330
(4) Flexible metallic tubing as permitted in Article 360
(5) Liquidtight flexible metal conduit in lengths not to exceed 1.22 m (4 ft), to connect physically adjustable equipment and devices permitted to be in these ducts.
(C) Other Space Used for Environmental Air (Plenums). This section shall apply to spaces not specifically fabricated for environmental air-handling purposes but used for air-handling purposes as a plenum. This section shall not apply to habitable rooms or areas of buildings, the prime purpose of which is not air handling.
Informational Note: The space over a hung ceiling used for environmental air-handling purposes and the space below a raised floor used for environmental air-handling purposes are examples 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 compression type fittings, intermediate metal conduit, or galvanized rigid metal conduit
(b) Type MI Cable as permitted in Article 332
(c) Type MC Cable employing a smooth or corrugated impervious metal sheath without an overall nonmetallic covering as permitted in Article 330
(d) Flexible metallic tubing as permitted in Article 360
(e) Liquidtight flexible metal conduit in lengths not to exceed 1.83 m (6 ft), to connect physically adjustable equipment and devices, other than lighting fixtures, permitted to be in these spaces.
(2) Luminaires and Electric 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 Code. Boxes shall have no holes and shall be provided with gasketed covers. Luminaires meeting these criteria and intended for use in this space shall be marked CCEA.
Informational Note 1: Criteria for CCEA (City of Chicago Environmental Air) may be obtained from Underwriters Laboratories.
Informational Note 2: 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 in accordance with 300.22(C) and Article 645."
(Amend Coun. J. 10-7-20, p. 21791, Art. III, § 3)