3com 4500 Quick Setup Guide

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C
HAPTER
 2: I
NSTALLING
 
THE
 S
WITCH
Connecting a 
Redundant Power 
Supply to your Switch 
4500 PWR
The Switch 4500 PWR 26 and 50 port have a -48V DC Redundant Power Supply 
socket that can be used in addition to the standard AC connection of the switch.  
If you intend to use this DC connection, please read this section.
WARNING: The installation of the Redundant Power Supply (RPS) should only be 
carried out by properly trained and qualified personnel.
WARNING: These instructions must be read in conjunction with the RPS flyer and 
the safety and installation instructions supplied with your RPS.
WARNING: When powering any Switch 4500 PWR from an RPS, the unit must be 
earthed (grounded). This can be achieved by either connecting the power cord to 
the unit or by connecting the earth terminal on the rear of the unit to a reliable 
electrical earth, or by connecting both. You must ensure that the earth connection 
is made before connecting the DC supply from the RPS.
3Com Switches which support -48V DC RPS inputs, that are PoE enabled, can only 
be powered by an RPS which complies with the isolation requirements of IEEE-Std 
802.3af. Non PoE enabled switches do not have this restriction.
WARNING: A standard 'positive-earthed' -48V redundant power system suitable 
for use with telecommunications equipment should not be used with the 3Com 
Power-over-Ethernet (PoE) network switches. In order to meet the IEEE 802.3af 
(PoE) specification, the -48V output must be isolated from earth (ground) and 
meet the isolation requirements in that specification.