645.5 Supply Circuits and Interconnecting Cables
- Power-supply cords shall not exceed 4.5 m (15 ft).
- Power cords shall be listed and a type permitted for use on listed information technology equipment or shall be constructed of listed flexible cord and listed attachment plugs and cord connectors of a type permitted for information technology equipment.
Informational Note: One method of determining if cords are of a type permitted for the purpose is found in UL 60950-1-2007, Safety of Information Technology Equipment — Safety — Part 1: General Requirements; or UL 62368-1-2012, Audio/Video, Information and Communication Technology Equipment — Part 1: Safety Requirements.
(a) The supply conductors shall be installed in accordance with the requirements of 300.11.
(b) In addition to the wiring methods of 300.22(C), the following wiring methods shall also be permitted:
- Rigid metal conduit
- Rigid nonmetallic conduit
- Intermediate metal conduit
- Electrical metallic tubing
- Electrical nonmetallic tubing
- Metal wireway
- Nonmetallic wireway
- Surface metal raceway with metal cover
- Surface nonmetallic raceway
- Flexible metal conduit
- Liquidtight flexible metal conduit
- Liquidtight flexible nonmetallic conduit
- Type MI cable
- Type MC cable
- Type AC cable
- Associated metallic and nonmetallic boxes or enclosures
- Type TC power and control tray cable
(2) Installation Requirements for Electrical Supply Cords, Data Cables, Interconnecting Cables, and Grounding Conductors Under a Raised Floor
- Supply cords of listed information technology equipment in accordance with 645.5(B).
- Interconnecting cables enclosed in a raceway.
- Equipment grounding conductors.
- Where the air space under a raised floor is protected by an automatic lire suppression system, in addition to wiring installed in compliance with 725.135(C), Types CL2R, CL3R, CL2, and CL3 and substitute cables including CMP, CMR, CM, and CMG installed in accordance with 725.154(A) shall be permitted under raised floors.
Informational Note: Figure 725.154(A) illustrates the cable substitution hierarchy for Class 2 and Class 3 cables.
- Where the air space under a raised floor is not protected by an automatic fire suppression system, in addition to wiring installed in compliance with 725.135(C), substitute cable Type CMP installed in accordance with 725.154(A) shall be permitted under raised floors.
- Listed Type DP cable having adequate fire-resistant characteristics suitable for use under raised floors of an information technology equipment room.
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 1685-2015, 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. 0.3-2014, Test Methods for Electrical Wires and Cables.
- Where the air space under a raised floor is protected by an automatic fire suppression system, optical fiber cables installed in accordance with 770.113(C), Types OFNR, OFCR, OFN, and OFC shall be permitted under raised floors.
- Where the air space under a raised floor is not protected by an automatic fire suppression system, only optical fiber cables installed in accordance with 770.113(C) shall be permitted under raised floors.