Power Over Ethernet "POE"

Power over Ethernet is a way to send electricity over an ethernet cable .
You can buy one already made or do one very easily .
The Ethernet Lan at 10/100 only uses 4 wires of the 8 that the Utp cable has (In the gigabit all the 8 wires are used).This means there are 4 we can use to send the power to a lan device like an access point .
The wires we can use are blue ,blue/white,brown,brown/white, (pins 4,5 and 7,8),if a certified cable and plugs are used .
In my case i used Rj45 plug non certified (digital telephone adapter) ,so i had to choose the pins 4,5 to the neutral(-) and 7,8 to the live(+).
I used a molex in order to connect a fan also to the POE.

This connector allows to connect a fan and any other device running on the same voltage

Sice i was adding more devices to it i had to get a higher Power Supply because the original one was not regulated and the voltage drop would be greater.
The voltage drop happens because of the resistance of the wires.
You can calculate it on this page