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Cisco CRS-1 Carrier Routing System 16-Slot Multishelf System Site Planning Guide
OL-7422-04
Chapter 2 16-Slot Fabric Card Chassis Installation Site Requirements
Fabric Card Chassis Power System Requirements
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One power shelf should be connected to four inputs from the “A” bus.
–
The other power shelf should be connected to four inputs from the “B” bus.
See the “DC Input Power Cables” section on page 2-5 and the “DC Power Shelf Wiring” section on
page 2-6 for more information about input power cables.
• An earth ground cable is required for each power shelf. We recommend that you use at least 6-AWG
multistrand copper wire, which is available from any commercial cable vendor.
The ground wire cable lug should be dual hole and able to fit over M6 terminal studs at 0.625-inch
(15.88-mm) centers (for example, Panduit part number LCD6-14A-L or equivalent). The cable lug
is similar to the cable lug for the input power cable. (See Figure 2-1.)
• All power connection wiring must conform to the rules and regulations in the National Electrical
Code (NEC) and any local codes. In addition, make sure that the wiring conforms to any internal
requirements at the installation site.
• Each DC power source must comply with the safety extra-low voltage (SELV) requirements in
UL 60950-1, CSA-C22.2 No. 60950-1, EN60950-1, AS/NZS 60950, and IEC60950-1.
• A DC-powered system should be installed in a restricted access area in accordance with the
National Electric Code, ANSI/NFPA 70.
• All components in the area where DC input power is accessible must be properly insulated.
• A readily accessible two-poled disconnect device must be incorporated in the fixed wiring.
Be sure to review the requirements in the “General Power and Grounding Requirements” section on
page 2-3.
DC Input Power Cables
Following is a list of the requirements for DC input power and ground connections:
• For DC input power cables, use the appropriate wire gauge for 60-amp service at nominal DC input
voltage (–48 or –60 VDC). We recommend that you use a commensurately rated, high-strand-count
copper wire cable. This cable is not available from Cisco Systems; it is available from any
commercial vendor.
Caution A certified electrician must select the appropriate DC input power cable based on standard electrical
practices, such as derating factors, wiring type, operating temperatures, and so on. The electrician must
verify that the cable complies with the National Electrical Code (NEC) and local codes and any
guidelines in effect at the installation site. At minimum, DC input power cables must be 6-AWG or
heavier and rated for 90°C (194°F) temperature or higher.
Note Tables A-3 and A-4 of the Cisco CRS-1 Carrier Routing System 16-Slot Line Card Chassis
Installation Guide describe DC wire gauges. Note, however, that this information is provided
for planning purposes only. A certified electrician must verify that the selected wire gauge and
rating is appropriate for the Cisco CRS-1 installation.
• Two pairs of cable leads, source DC (–) and source DC return (+), are required for each power
module in a power shelf. This requirement means that four wires (two pairs) are needed for each
power module, or eight total wires (four pairs) for each power shelf, and one grounding wire for the
shelf.