•
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 power module when making the measurement.
•
A green (or green and yellow) cable typically indicates that it is a ground cable.
DC power modules contain reverse voltage protection circuitry to prevent damage to the power module
if it detects a reverse polarity condition. No damage should occur from reverse polarity, but you should
correct a reverse polarity condition immediately.
Caution
For a list of the nominal and acceptable value ranges for source DC power, see
page 273
The rating label is shown in the figure below.
Figure 87: Rating Label for NCS 4009 DC Chassis
NEBS Supplemental Unit Bonding and Grounding Guidelines
You must connect the central office ground system or interior equipment grounding system permanently to
the supplemental bonding and grounding connection on the side of the chassis to meet Network Equipment
Building System (NEBS) requirements as well as safety compliance requirements. This grounding point is
referred to as the NEBS bonding and grounding point.
Hardware Installation Guide for Cisco NCS 4000 Series
167
Installing Power Components
NEBS Supplemental Unit Bonding and Grounding Guidelines
