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Cisco MGX 8220 Installation and Configuration
Release 5.0, Part Number 78-6430-03 Rev. D0, November 2003
Chapter
Site Preparation
Site Preparation
Site preparation involves rack space, power, and cooling considerations.
Rack Space
The MGX 8220 shelf is designed for mounting in a standard 19-inch rack. The MGX 8220 site requires
a 19-inch rack with sufficient available mounting units for the modules to be installed.
• 5U for each shelf
• 3U for the main cooling assembly
• 2U for the booster cooling assembly
• 2U for the plenum chamber
• 1U for the spacer unit
• 3U for the AC power module
The rack should have a set of mounting rails at the front and a second set at the rear or in a designated
intermediate position. There must be sufficient clearance around the rack to allow removal and
replacement of front and back cards and for the attachment and routing of cables to the line modules.
Ideally, there should be at least three feet clearance in the front of the rack and two feet clearance in the
back of the rack.
Power
The MGX 8220 shelf can be configured for either AC or DC power.
An easily accessible AC or DC power source must be available within six feet of the MGX 8220 system.
Before powering up the node, verify that the MGX 8220 node is powered from a dedicated branch
circuit. An easily accessible disconnect device should be included in the facility wiring.
• DC Version
For the DC version, a 48V DC power feed is required. For power supply redundancy, two such
power feeds (preferably from independent power sources) are required. Each power feed must be
capable of supplying 500W.
A 20A DC circuit breaker is recommended for the 48V DC power source that supplies DC power
to each MGX 8220 shelf. In North America this circuit breaker should protect against excess
currents, short circuits, and earth faults in accordance with national and local electrical codes.
These codes are mentioned in the section, “Safety Recommendations.” The dedicated circuit
breaker should be sized so that the rated current and the trip delay is higher and longer than the
MGX 8220 circuit breaker. A 20A, 1-pole DC circuit breaker with a long trip delay is
recommended.
For information purposes, the MGX 8220 shelf uses a 15A, 1-pole DC circuit breaker with medium
trip delay on the -48V input. The circuit breaker manufacturer is ETA (part number
43-500-P10-15A).
The DC power connectors attach to the power entry modules at the rear of the shelf through
Euro-block 3-pin connectors. For power and ground connections to the MGX 8220 shelf, 12 AWG
conductors must be used. If the 48V DC source has wires of a different gage, which accepts the
source wires as input and provides as output 12 AWG wires to the MGX 8220 DC connector, a