Cisco Systems MGX 8230 manual Bonding and Grounding

Chapter 3 Site Preparation

Power and Grounding

For DC supply connections, consult local or national codes for conductor sizing. Conductors must be suitable for 30 Amps. Wiring that is 10 AWG (4 square millimeters) is adequate.

Bonding and Grounding

To maintain the full EMI and EMC integrity of this equipment, it must be bonded to an integrated ground plane or an isolated ground plane network. The purpose of this requirement is to mitigate the damaging effects to equipment from electrostatic discharge and lightning. Refer to the latest edition of ITU Recommendation K.27 or Bellcore GR-1089-CORE requirements to ensure that the correct bonding and grounding procedures are followed. As recommended in these documents, a frame bonding connection is provided on the Cisco-supplied cabinet for rack-mounted systems.

Refer to the section “Making the Frame Bonding (Ground) Connection” in the IGX or the BPX installation documents for information on how to make a connection.

Note Except for the AC power supply module, every module in a rack-mount system relies on the rack itself for grounding. Therefore, the rack must be properly connected to protective earth before operating the system.

A DC-powered node must have grounding conductors that connect at two separate locations, as follows:

•The grounding conductor provided with the supply source must connect to the correct terminal of the Power Entry Module (PEM).

•A grounding conductor as described previously must connect to the appropriate terminal of a rack assembly or to the grounding point on the lower-right corner of the MGX 8230 chassis rear panel.

Wiring a Mixed Ground System with Redundant Supplies

A mixed ground system appears in Figure 3-3. This figure shows safety and earth grounds and the primary and redundant DC sources Battery A and Battery B. Individual ground conductors are labeled Z1, Z2, ..., Z5. The Z represents the impedance of the ground conductor between a chassis, for example, and a connection to the building’s ground system. The numbers 1, ..., 4 represent building ground points and indicate that an impedance can exist between different points in the ground system of the building. Each of these symbols indicate that a voltage drop may result (but must not exceed 2 percent of the referenced voltage). See Table 3-1for a definition of each Z1–Z5.

	Cisco MGX 8230 Edge Concentrator Installation and Configuration
3-18	Release 1.1.31, Part Number 78-11215-03 Rev. B0, May 2001