HP Power over Ethernet (PoE/PoE+) Planning and Implementation Guide

12-6
Planning and Implementation for the HP 3800-PoE+ Switches
Planning the PoE+ Configuration
• When installed in the HP 3800-48G-PoE+-4SFP+ or HP 3800-48G-
PoE+-4XG Switch, 185 W is reserved for system operation leaving 815
W for PoE/PoE+ operation. When a second power supply is installed
the total amount of wattage can be allocated for PoE/PoE+ operation
up to 1080 watts. Limiting the total number of PoE+ ports to 36.
Once you have selected your specific configuration and the PoE or PoE+
power provided, you then add up the maximum amount of power each device
requires (use maximum power in watts, usually found on a product’s data
sheet). Adjust this total maximum power figure by adding 16% to account for
possible line loss. This value must be less than the maximum power available
shown in the table for your configuration.
All these calculations assume worst-case device power and 100M cables and
are the most conservative estimate of what can be supported. Actual power
usage and number of devices supported will be different in each case.
HP 3800-24G-PoE+-2SFP+ or HP 3800-24G-PoE+-2XG
Switch Configurations
The table in this example configuration contains entries that show the PoE+
power available for the HP 3800-24G-PoE+-2SFP+ or HP 3800-24G-PoE+-2XG
Switch when using only one power supply.
Figure 12-1. Example of the HP 3800-24G-PoE+-2SFP+ or HP 3800-24G-PoE+-2XG
Switch with one power supply installed
19 ports can supply up to 30 watts
of PoE+ power or 24 ports can
supply 15.4 watts of PoE power