Chapter 2 Preparing for Installation
Site Requirement Guidelines
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
•In some cases, the source DC cable leads might have a positive (+) or a negative
(+) and negative
•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 Table
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
(Figure 2-10). 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.
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