Power Over Ethernet (PoE and PoE+) Explained - GoTechTalk


Saturday, August 21, 2021

Power Over Ethernet (PoE and PoE+) Explained

Hello everyone, so today I want to take a look at PoE (Power Over Ethernet) what is it and why should you use it so if you want to find out more please keep reading.

Now inside the cables that we use for our wired local area networks, there are a number of different strands different individual wires that are used to carry the data back and forth and they can also be used to carry not only data but also power and that means that there is a system called Power Over Ethernet a way of sending electricity over an ethernet cable so that when you plug it into a device it can be powered from the current and the voltage that's going over that cable and you don't need a second power supply, that's really useful when you want to reduce the wiring that's needed for each individual device for example like Access Points you've got one mounted on your wall let's say do you want to run an ethernet cable to it and then a power cable to it and then work out where all they go and where's the nearest plug so you can plug it in. Wouldn't it be much nice if you just plug in the ethernet cable and that transfers the data and the power at the same time.

So, to transfer the data and the power at the same time we need device that puts the power onto the ethernet cable technically that's called PSE a Power Source Equipment and there are two main ways of doing it.

TP-LINK TL-PoE150S PoE Injector Adapter, IEEE 802.3af Compliant, up to 100 Meters (325 Feet),Gigabit -10/100/1000,Black
TP-LINK TL-PoE150S PoE Injector Adapter, IEEE 802.3af Compliant, up to 100 Meters (325 Feet),Gigabit -10/100/1000,Black
  • You buy a switch let's say you're buying a new gigabit ethernet switch and some of the ports on that switch provide PoE so the moment you put in that cable you have the option of having power going down that line that means if you've got a switch and you've got a few devices connected to it you can actually just run them off the Access Points or whatever device it is you're going to connect to it just from that point and they have power and they have data connectivity

Now there are several standards around the whole power over ethernet the two that you probably need to worry about are PoE (power over ethernet) and PoE+. So, one is the 802.3 AF standard from 2003 and it provides up to 12.95 watts over the cable and that was upgraded in 2009 to the 802.38 standard which provides up to 25.5 watts and that's called PoE+.

The great thing about PoE+ it's backwards compatible which means if you have a PoE switch power of the unit switch or an injector you can still plug in a normal PoE device and it will just use the right amount of power.

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