Allied Telesis AT-S81 - Manual (Page 90)

Chapter 8: Power Over Ethernet
90 Section I: Using the Menus Interface
Power Over Ethernet menu, shown in Figure 18 on page 91.
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.