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Cisco MGX 8850 Multiservice Switch Installation and Configuration
Release 1.1.31, Part Number 78-11223-03 Rev. B0, May 2005
Chapter 3 Site Preparation
Power and Grounding
Power and Grounding
This section describes the requirements for electrical power and grounding the switch and the site. These
requirements apply to Central Office (CO) and Private Enterprise (PE) sites.
AC Power Circuit Breakers
AC power must come from dedicated, AC branch circuits. Each circuit must be protected by a dedicated,
two-pole circuit breaker. The circuit breakers at the source must have a rated current and trip delay
greater than those of the MGX 8850 circuit breaker. Cisco recommends that the site has a 20A, 2-pole
AC circuit breaker with a long trip delay at each branch circuit.
The MGX 8850 uses a 20A, 2-pole circuit breaker for each AC input. The manufacturer of this circuit
breaker is ETA. The ETA part number is 8340-F120-P1P2-B2H020A.
DC Power Circuit Breakers
For a DC-powered system, verify that its power comes from a dedicated DC branch circuit. This branch
circuit must be protected by a dedicated circuit breaker. The circuit breaker must have a rated current
and trip delay that is greater than those of the MGX 8850 circuit breaker. Cisco Systems recommends
the site have a dedicated 60A, 1-pole circuit breaker with a medium trip delay at each branch circuit.
DC-powered nodes use a 60A, 1-pole circuit breaker with a short trip delay on each –48V input.
Electrical Power for AC-Powered Nodes
The MGX 8850 AC power requirement are 220 VAC with a worst-case range of 180–240 VAC or
110 VAC with a worst case range 100—240 VAC. See also Appendix A, “System Specifications.” The
AC power source must be within 6 feet (1.8 m) of the system and easily accessible. Before turning on
the power, verify that the power supplied to the node comes from a dedicated branch circuit.
The 110 VAC power supply has a maximum output power of 1200W per power supply module. However,
safety limitations of the line cord, the 110 VAC power supply output power is limited to the values shown
in Table 3-1.
The 220 VAC power supply module has a maximum power output of 2500W with two fan trays and
1500W with one fan tray. Only use 220 VAC power supply modules with the Cisco MGX 8230 and Cisco
MGX 8250 nodes. 220 VAC power supply modules are not used in Cisco MGX 8850 PXM1-based
nodes.
Table 3-1 110 VAC Power Module Output Power
Input voltage (Volts AC) Power output (Watts)
100 900
110 1000
120 1100
130–264 1200