Power over Ethernet (PoE): Power Injector, Power Splitter, and POE switches 1

Power over Ethernet (PoE): Power Injector, Power Splitter, and POE switches

Power over Ethernet (PoE) is a method to deliver electrical power to the device using existing Ethernet cable. This omits the requirement to have a power source near the device. This method is very useful when we are deploying devices that attached to a high pole or remote area when electrical power is rare especially outdoor.

PoE Injector

Not only outdoor, PoE also very useful when using indoor for esthetic and simplicity of installation. No power source needs near the device which compliant with POE standard. Devices that usually incorporate POE standard are Access Point, CCTV camera, IP telephony. We are talking about some PoE related terms like power injector, power splitter, active PoE, passive PoE, Cisco PoE and non-Cisco PoE. What they are and how we can utilize them to our IT equipment.

1. What is Power over Ethernet (POE)

POE using an unused cable in UTP/UTP cable wiring. In networking standard IEEE 802.3af pin no 4,5,7, and 8 are used to deliver power to the device. In early days these pins used for telephone cable. The cable distance between POE injector and device can up to 100 meters.

2. What is power Injector (power source)

A device that injecting power via Ethernet cable (UTP or STP). Power injector usually in form of an adaptor with 2 ports Ethernet. The 1st port connected to switch that carry data signal, the 2nd port connected to POE device and contains power 48volts. POE injector follows POE standard having 44-48 volts DC and 350mA on their port.
This adaptor is also referred to as active POE because it injects separate power using their own adaptor. The distance of UTP cable between active POE and the device can p to 100 meters. I personally recommend using this to avoid the problem.

3. What is POE power Splitter

The device that split power and data to non POE compliant devices. Below is POE splitter picture, it’s a simple connector that split between data and power. This power splitter will use existing power adaptor of a device. Maximum distance UTP cable is 30-40 meters.
This POE splitter sometime referred as Passive POE because deliver power passively to the device, they don’t ship with an adaptor. They use an existing adapter to power up the device. The longer the UTP cable it will decrease electricity current and voltage and causing a problem.

PoE switch

POE switch is a switch that has power in their ports. By using PoE switch you don’t need additional power injector. Just plug your POE compliant devices into the switch and it should ON without power adaptor. PoE switch usually used for VoIP handset but it also can be used for CCTV or Access point.

Cisco PoE Power Injector and switches

Cisco POE has slightly different cable wiring but it still compliant with PoE standard. That is why you cannot use Cisco POE adaptor to power up non-Cisco devices. You also cannot use a non-Cisco power injector to power up Cisco POE devices such as Access point and IP telephony.
By swapping cable pin in RJ-45 connector you can use it to overcome the obstacle I wrote this on other posts here.

Non Cisco PoE devices and Power Injector

Usually non-Cisco PoE brand devices interchangeably with another brand. We can be mixed with different brand between POE power injector and POE device compliant.

PoE Injector and splitter implementation

To get a better understanding of differences above, I show you below how we can implement PoE injector and splitter in the real world.

Power Injector Only

Power injector implementation is easy, no configuration required. Just plug data port on PoE injector to switch or router, you will need power outlet around for PoE injector.

Port data+power in PoE injector need to be connected to PoE device enable such as IP camera, IP phone, or Access point. Remember that not all IP camera, IP phone, or Access point are PoE enable. UTP cable from power injector to the device can up to 100 meters.

PoE Splitter only

PoE splitter is for non-PoE enable device, the installation a bit different wit PoE injector, where the other end of splitter needs to be installed near the device. The UTP distance between PoE splitter connected can up to 40 meters.

PoE injector combined with PoE Injector

PoE for injector and PoE splitter can reach up to 100 meters for non-POE device without requiring a power outlet.

There is a great product from TP link that makes it possible to extend POE injector to non-PoE powered device up to 100 meters. Using 2 devices PoE Injector TL-POE150S and PoE splitter TL-POE10R we can power up non-PoE device up to 100 away from power source. The output voltage for a device is selectable from 5,9, and 12 volts.

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