Power over Ethernet (POE)
As its name, POE, power over ethernet is using ethernet cable as a power resource, by this, it means you’re saving some spaces for using power supply. But basically this were often use for wireless access point devices, cause its place are close with ethernet cable and because placement of the devices might be in somewhere far from power supply.
Power over Ethernet is required to perform the injection power supply to the Wireless In A Box is mounted on a tower, POE beneficial to reduce power losses (losses) due to the use of cables and connectors. Lets have look on it.
Actually there are some devices that are commonly using it, which as described above wireless access point, and telephone or fax machine. The POE devices are quite small, and yet functionable, as you could see from the image above.
POE using 2-pair UTP cable is not used, one pair for injection + (positive) power and a pair for injection – (negative) power, used the cable pair (a pair) to avoid loss of power due to cable loss.
Note that the most crucial problems in the manufacture of POE is how to prevent the occurrence of short, because the cable and power connector cross section of small and easily moved or are interested in, cover it with wax or gel insulator so that each point of connection is protected from short power.
Although you do could buy POE devices, but some people are trying to build it their own.
As you could see above, some using the positive power and negative power and connect it directly to power sources, and there it goes, your own home made POE, but always consider the risk that I have mention earlier.