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5
Infrastructure Requirements
Air conditioning
Power supplies create a great amount of heat. Ensure you have enough cool
air to maintain an ambient temperature between 0°C to 50°C (32°F to 131°F)
around the switch devices inside the rack.
A typical 48 port PoE switch BTU rating is approximately 920. Adding in a
maximum number of PoE powered devices (PD) connected to the switch at
15.4 watts, the BTU rating can jump to approximately 2280. Although typically
the PDs are outside of the data closet area, the total BTU needs of the air
conditioning system (for the whole building for example) needs to take this
additional cooling requirement into consideration.
When adding a Redundant Power Supply (RPS), the BTU rating can grow to
approximately 3500 and more. This example only takes in to consideration
one PoE switch with redundant power. As more switches, PoE PDs, and
redundant power supplies are added the BTU rating increases requiring more
cooling.
Ensure wiring closets and other areas where PoE switches and power supplies
are congregated have proper cooling. Even though most PDs do not draw the
maximum 15.4 watts, it is still good to plan for the maximum.
Power requirements
Ensure you have enough power supplied to the area where the switches will
be mounted. Some units have dual power supplies in them that you may want
to consider connecting each power supply to different circuits in order to
provide redundant power to the switch.
Many switches come with dual power ratings (110 or 220 volt operation).
Therefore planning for power requirements is critical. If a wiring closet
currently only supplies 110 volts it must be determined whether or not to
operate the switch at 110 volts or 220 volts.
You not only need to plan for voltage requirements but amperage
requirements. PoE switches can double or triple the amperage draw to that of
a non-PoE switch.
5-1
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