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The provisions of Article 640 of NFPA 70 are adopted by reference with the following modifications.
1. Revise subsection 640.3(B) to read, with no exceptions or notes:
"Ducts, Plenums, and Other Air-Handling Spaces. Section 300.22(B) shall apply to circuits and equipment installed in ducts specifically fabricated for environmental air. Section 300.22(C) shall apply to circuits and equipment installed in other spaces used for environmental air (plenums)."
2. Revise subsection 640.23 to read:
"Conduit or Tubing. The number of conductors permitted in a single conduit or tubing shall not exceed the percentage fill specified in Table 1, Chapter 9."
3. Revise subsection 640.24 to read:
"Wireways, Gutters, and Auxiliary Gutters. The use of metallic wireways, gutters, and auxiliary gutters shall be permitted for use with audio signal conductors and shall comply with applicable articles with respect to permitted locations, construction, and fill."
The provisions of Article 645 of NFPA 70 are adopted by reference with the following modifications:
1. Revise subsection 645.3(B) to read:
"Plenums. Section 300.22(C) shall apply to wiring and cabling in other spaces used for environmental air (plenums) in or above an information technology equipment room."
2. Revise subsection 645.5(E) to read:
"Under Raised Floors. Power cables, communications cables, connecting cables, interconnecting cables, cord- and-plug connections, and receptacles associated with the information technology equipment shall be permitted under a raised floor, provided the following conditions are met:
(1) The raised floor is of approved construction, and the area under the floor is accessible.
(2) The branch-circuit supply conductors to receptacles or field-wired equipment are in rigid metal conduit, intermediate metal conduit, electrical metallic tubing, metal wireway, surface metal raceway with metal cover, flexible metal conduit, liquidtight flexible metal conduit, and associated metallic boxes or enclosures as permitted in Chapter 3. These supply conductors shall be installed in accordance with the requirements of 300.11.
(3) Ventilation in the underfloor area is used for the information technology equipment room only, except as provided in 645.4(2). The ventilation system shall be so arranged, with approved smoke detection devices, that upon the detection of fire or products of combustion in the underfloor space, the circulation of air will cease.
(5)* Openings in the raised floor for cords and cables protect cords and cables against abrasion and minimize the entrance of debris beneath the floor.
* Editor’s note– As numbered in Coun. J. 9-6-17, p. 55278, § 1. Future legislation will correct the provision if needed.
(6) Cables, other than those covered in 645.5(E)(2) and (E)(3), are one of the following:
a. Listed DP cable having adequate fire-resistant characteristics suitable for use under raised floors of an information technology equipment room.
b. Interconnecting cables enclosed in a raceway.
c. Equipment grounding conductors
Informational Note: One method of defining fire resistance is by establishing that the cables do not spread fire to the top of the tray in the "UL Flame Exposure, Vertical Tray Flame Test" in UL 1685-2011, Standard for Safety for Vertical-Tray Fire-Propagation and Smoke-Release Test for Electrical and Optical-Fiber Cables. The smoke measurements in the test method are not applicable.
Another method of defining fire resistance is for the damage (char length) not to exceed 1.5 m (4 ft 11 in.) when performing the CSA "Vertical Flame Test – Cables in Cable Trays," as described in CSA C22.2 No. 0.3-M-2001, Test Methods for Electrical Wires and Cables."
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