Allied Telesis AT 8000/8POE - Manual (Page 106)

Chapter 8: Power Over Ethernet
106 Section I: Using the Menus Interface
Note
The standard specifies five classes, but the fifth is reserved for
future use.
Manufacturers set the power class of their PoE powered devices. You
cannot adjust this. You can view the power class of each device in the
Power Over Ethernet menu, shown in Figure 26 on page 107.
Even though each port is capable of supplying up to 15.4 W, the standard
calls for a maximum power consumption of 12.95 W, 2.45 W less than the
port can supply. This extra capability is to compensate for possible line
loss. Some power is likely to be lost on the twisted pair cable as it travels
from the switch to the device. For devices that require 12.95 W, the extra
watts act as compensation for this possible loss.