Cisco XR 12410 User Manual
Page 68
Chapter 2 Preparing for Installation
Site Requirement Guidelines
2-18
Cisco XR 12410 and Cisco XR 12810 Router Installation Guide
OL-17441-01
The color coding of source DC power cable leads depends on the color coding of
the site DC power source. Because there is no color code standard for source
DC wiring, be sure that power source cables are connected to the PDU using the
proper positive (+) and negative (–) polarity:
•
In some cases, the source DC cable leads might have a positive (+) or a
negative (–) label. This is a relatively safe indication of the polarity, but you
must verify the polarity by measuring the voltage between the DC cable leads.
Be sure that the positive (+) and negative (–) cable leads match the positive
(+) and negative (–) labels on the PDU when making the measurement.
•
A green (or green and yellow) cable typically indicate that it is a ground
cable.
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
.
NEBS Supplemental Unit Bonding and Grounding Guidelines
Although the router chassis requires a safety earth ground connection as part of
the power cabling to PDUs, we also recommend that you connect the central
office ground system or interior equipment grounding system to the supplemental
bonding and grounding connections on the back of the router chassis
(
). This grounding point is also referred to as the network equipment
building system (NEBS) bonding and grounding studs.
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
PDUs.