Article 645 Information Technology Equipment

645.1

Scope

This article covers all types of wiring, equipment, grounding power supply, and equipment interconnect, in information technology equipment rooms. The reader can refer to this article as well as NFPA 75-1999 Standard for the Protection of Electronic Computer/Data Processing Equipment (whose rules this room must comply with) for further information.

645.4

Special Requirements for Information Technology Equipment Room

Article 645 will apply if all the following are met: (1) Disconnecting means are provided that are in accordance with Section 645.10; (2) a separate HVAC system is provided for the room, or another system in another area is used if fire/smoke dampers which operate from smoke detectors and operate from a disconnecting means required by Section 645.10 are provided in the ducts at the point of entry into the room; (3) the information technology equipment is listed; (4) the room is occupied only by the personnel needed to operate and maintain the equipment; (5) fire-resistant-rated walls and floors and ceilings with protected openings are used to separate the area from other areas.

645.5

Supply Circuits and Interconnecting Cables

(A) The ampacity of the branch-circuit conductors supplying units must be at least 125% of the total connected load.

(B) The data processing system can be connected to branch circuits using flexible cords and attachment plug caps not exceeding 4.5 m (15 ft.), or cord set assemblies. If a cord set assembly is used on the floor, it must be protected from physical damage.

(C) Separate units can be interconnected with cables and cable assemblies. They must be listed for this use and protected from physical damage.

(D) There are a number of rules for circuits, cables, and devices under a raised floor. Cables and receptacles are allowed to be installed under a raised floor. The area under the floor has to be accessible and the floor must be of proper construction. Branch-circuit conductors must be installed in rigid or intermediate metal conduit, rigid nonmetallic conduit, electrical metallic tubing, electrical nonmetallic tubing, metal wireway, surface metal raceway with a metal cover, nonmetallic surface raceway, nonmetallic wireway, flexible metal conduit, liquidtight flexible metal or nonmetallic conduit, Type MI cable, Type MC cable, or Type AC cable and installed in accordance with Section 300.11. The openings in the raised floor for cables have protection against abrasion to the cables and a means to minimize the debris that will fall onto the floor. The ventilation system underfloor must have smoke detection that will shut off the circulation of air when a fire or products of combustion are detected. Cables other than those listed above must be listed as type DP cable with adequate fire-resistance to be used under a raised floor. There are conditions where this is not required. Abandoned cables are permitted to remain if installed within a metal raceway

(E) All cables and accessories that are part of or used for the equipment have to be properly secured in place.

645.6

Cables Not in Information Technology Equipment Room

All cables that go outside the room have to comply with the NEC®.

645.7

Penetrations

Utilize Section 300.21 for rules applying to all penetrations of the fire-resistant separation of the room.

645.10

Disconnecting Means

Disconnecting means must be provided for all system equipment, HVAC equipment and fire/smoke dampers. This can be one central one or separate ones for different types of equipment. The disconnects have to be grouped together, identified, and be accessible at the principal exit. The exception is for those installations under Article 685.

645.11

Uninterruptible Power Supplies (UPS)

These are commonly referred to as UPS. These systems have to comply with Section 645.10. The disconnecting means must disconnect the battery from its load. There are two exceptions.

645.15

Grounding

All exposed noncurrent-carrying metallic parts of an information technology system has to be grounded as noted in Article 250 or be double insulated. If the derived power system is in listed equipment and supplies power to systems through cable assemblies or receptacles which are part of the equipment, it is not considered a separately derived system as per Section 250.20(D). If signal reference structures are installed, they have to be bonded to the equipment grounding system of the computer equipment.

645.16

Marking

Each piece of system equipment supplied by a branch circuit must have a manufacturer's nameplate. The nameplate must show the maximum rated load in amperes, voltage, and frequency.

645.17

Power Distribution Units

Multiple panelboards are permitted in a single cabinet provided there are no more than 42 overcurrent devices in each panelboard and the power distribution unit is listed for information technology application.

The following article titles are listed for reference: Article 647Sensitive Electronic Equipment; Article 650Pipe Organs; Article 660X-Ray Equipment; Article 665Induction and Dielectric Heating Equipment; Article 668Electrolytic Cells; Article 669Electroplating; Article 670Industrial Machinery; Article 675Electrically Driven or Controlled Irrigation Machines; Article 680Swimming Pools, Fountains, and Similar Installations; Article 682Natural and Artificially Made Bodies of Water; Article 685Integrated Electrical Systems; Article 690Solar Photovoltaic Systems; Article 692Fuel Cell Systems; Article 695Fire Pumps.