Cisco XR 12416 - Manual (Page 21)

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Cisco XR 12416 and Cisco XR 12816 Router Chassis Installation Guide
OL-17440-01
Chapter 2 Preparing for Installation
Site Requirement Guidelines
Caution DC PEMs contains circuitry to trip the breaker on the PEM if the PEM detects a
reverse polarity condition. No damage should occur from reverse polarity, but you
should correct a reverse polarity condition immediately.
For a list of the nominal and acceptable value ranges for source DC power, refer
to
Table A-3 on page A-4 .
NEBS Supplemental Unit Bonding and Grounding Guidelines
Although the router chassis requires a safety earth ground connection as part of
the power cabling to the power shelf, we also recommend that you connect the
central office ground system or interior equipment grounding system to the
supplemental bonding and grounding connections.
Supplemental connections are located at the top of the power interface panel on
the back of the chassis (
Figure 2-9 ), and near the lower corners of the switch
fabric card cage on the front flanges of the chassis ( Figure 2-10 ). The DC return
of this system should remain isolated from the system frame and chassis (DC-I).
This grounding points are also referred to as the network equipment building
system (NEBS) bonding and grounding connections.
Note These bonding and grounding connections satisfy the Telcordia NEBS
requirements for supplemental bonding and grounding connections. If you are not
installing the router in a NEBS environment, you can choose to bypass these
guidelines and rely on the safety earth ground connections to the AC and DC
power shelves.