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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 c ooling considerations.

Rack Space

The MGX 8220 shelf is designed for mounting in a sta ndar d 19- in ch rack. The MGX 82 20 sit e req ui res
a 19-inch rack with sufficient available m o un ti ng u n its for the modules to be installed .
•5U for each shelf
•3U for the main cooling a ssembly
•2U for the booster c oo li ng 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 th e f r on t a nd a seco n d se t at the rear or in a designated
intermediate position. There m u st be s u fficient cl ear an ce ar o un d th e r ac k to al low removal and
replacement of front and back car d s an d f or t he attachment and routing of cabl es t o th e l in e m odules.
Ideally, there should be at least thr ee feet clearance in the front o f the rack and two feet clearanc e 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 av ailabl e within six feet of the MGX 8220 s ystem.
Before powering up the node, verify that the MGX 8220 node is powered from a dedicated branch
circuit. An easily accessible d isc on ne ct devi ce s hou ld b e i nc luded 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 reco m me nded for the 48V DC power source th at s upp li es D C p ower
to each MGX 8220 shelf. In North America this circuit breaker should protect against excess
currents, short circuits, and e ar th fa ul ts i n acc or d an ce wi th n at io na l a nd local electrical codes.
These codes are mentioned in t he sec tion, “Safety Recommendatio n s.” 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 8 220 shel f use s a 15 A, 1-p ol e DC c ircu it brea ker wit h 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 t h e p ower en tr y mod u les at the rear of the shelf through
Euro-block 3-pin connectors. For power and ground connections to the MGX 8220 shelf, 12AWG
conductors must be used. If th e 4 8 V D C sou r ce h as wires of a different gage, which ac cep ts the
source wires as input and provides as output 12 AWG wires to the MGX 8220 DC connector, a