Power over Ethernet Injectors - All you need to know!
A PoE injector connects your PoE-enabled network device to a non-PoE LAN switch port.
More specifically, a PoE injector can be used to connect a wireless access point, IP phone, network camera or any IEEE 802.3af/at-powered device (PD) to a network switch. Using a PoE injector avoids the need to run AC power lines for your wireless access point, network camera or IP phone, because you use the existing LAN cabling to deliver both DC power as well as data.
How much power (W) can it provide?
IEEE-compliant PoE injectors are able to output anywhere from 12 watts to over 70 watts of power.
|PoE Standard||PoE Common Name||Power Output||Comment|
|IEEE 802.3af||PoE||15.40 W||12.95 W power available for connected device (PD)|
|IEEE 802.3at||PoE+||30 W||25.50 W power available for connected device (PD)|
|IEEE 802.3bt Type 3||4PPoE, Ultra PoE||60 W||51 W power available for connected device (PD)|
|IEEE 802.3bt Type 4||Ultra PoE||100 W||71 W power available for connected device (PD)|
What kind of cable do I need?
PoE injectors are based upon the rules defined by the IEEE 802.3 working group. As such, no special cabling is required. Keep in mind, though, that Ultra-PoE connections require 8-pin network cabling. Almost all networking cabling is 8-pin, but the very cheapest cables out there may only come with 4-pins.
|PoE Standard||Minimum Cable Category||Pins required||Supported Modes|
|IEEE 802.3af||Category 3||4-pins / 2-pairs||Mode A, Mode B|
|IEEE 802.3at||Category 5||4-pins / 2-pairs||Mode A, Mode B|
|IEEE 802.3bt Type 3||Category 5||8-pins / 4 pairs||4-pair|
|IEEE 802.3bt Type 4||Category 5||8-pins / 4 pairs||4-pair|
Can I use CCA Cable?
CCA stands for Copper-Clad Aluminium. CCA cabling, also referred to as Cu/Al, utilizes an aluminium core that is coated with copper, which contrasts regular network cabling that uses 100% copper for the conductor. The cost of CCA cabling is generally lower than the cost of a network cable made from 100% copper. A lot of information (and misinformation) about the drawbacks of CCA cables can be found online, and while CCA cables usually get the job done just fine when used for standard networking applications, we do not recommend their use when using PoE injectors or switches.
Why can't I use CCA cables with PoE?
Can you use CCA network cables with PoE? Yes, you can. Should you? No.
Aluminium (or as some might say, aluminum) isn't as good an electrical conductor as copper, which is due to the higher DC-resistance value of aluminium versus copper cable. Higher resistance of CCA cable means that more power is lost and dissipated as heat, and the longer the cable connection, the worse the issue becomes. The higher heat is a major concern, as is the larger power loss on the cable.
So in conclusion: Play it safe and demand 100% copper network cabling from your supplier.
Is using a PoE Injector safe? Can it damage my equipment?
IEEE 802.3af/at/bt compliant PoE injectors are very safe. They will not damage any equipment, even if the equipment is not designed for PoE applications. Before the PoE injector sends any power to the connected powered device (PD), such as the VoIP phone, the injector initiates a handshake procedure. That procedure utilizes low voltage and is harmless to any connected device, PoE or non-PoE. During the handshake procedure, certain key parameters are established, most of which are related to how much power is required by the connected device. Once the handshake is completed, the PoE injector begins sending power, which will trigger the connected device to start up. Should that handshake not complete successfully for any reason, the PoE injector will never send any power. It is this built-in feature of all IEEE 802.3af/at/bt-compliant devices that makes the technology so inherently safe.
What are the advantages of using a PoE Injector?
PoE technology offers several benefits.
First, the delivery of data and power over a standard Ethernet cable eliminates the need for AC/DC power supplies and outlets. That lowers the cost as no electrician is required for the installation of new devices in areas where no power is present. Additionally, regular Ethernet networking cabling is rather inexpensive and is often already installed in the location.
Second, and this isn't strictly relevant to PoE injectors, with PoE technology in general, there are fewer points of failure. Connect your PoE switch to an uninterruptible power supply (UPS) and your PoE powered devices are guaranteed a constant power delivery, which is so important for mission-critical devices such as a PoE security camera.
Finally, PoE installations that utilize managed PoE switches allow you to remotely restart connected PoE devices, either manually or based on a schedule. Modern PoE switches are equipped with watchdog functionality (i.e. Powered Device Manager (PDM)) which can help to greatly reduce the downtime of your connected devices.