POWER OVER ETHERNET INJECTORS
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Frequently Asked Questions about PoE Injectors
What kind of cable do I need?
PoE injectors are based on the IEEE 802.3 standards. Cat 5 or higher Ethernet cables are available and will work with PoE injectors. Please note that with PoE injectors using PoE++ or Hi-PoE standards, Cat 6a cables are recommended.
Does a PoE injector have manageable ports?
No. If you need a management feature, you should choose a PoE switch.
Will a PoE injector damage my equipment?
IEEE 802.3af/at/bt-compliant PoE injectors are safe and will not harm any equipment, even if it is not designed for PoE applications. This is because the PoE injector has a built-in handshake procedure. Before it sends any power to the connected PD, if the handshake is not successfully completed for any reason, the PoE injector will not send any power. Therefore, all IEEE 802.3-compliant devices are inherently safe.
What should I take into consideration before purchasing a PoE injector?
You will need to consider three things:
- The number of PDs on your network: For several PDs, the number of PoE injector ports must match the number of PDs to be connected.
- PoE port power supply: Make sure the PoE injector’s PoE standard is compliant with those of your PDs. For example, The 802.3af (PoE) standard supplies up to 15.4W, 802.3at (PoE+) supplies up to 30W, and 802.3bt (PoE++/Hi-PoE) supplies up to 60W/100W.
- Power supply voltage: Make sure the PoE injector’s voltage is compliant with the PD.
Can I use a PoE injector to power a Gigabit switch?
Not unless the switch has a port that allows for PoE power.
How close does a PoE injector need to be?
The PoE injector must be within the Ethernet cable distance limitation of 100 m (328 ft.). If you need more distance, a PoE extender will be the solution.
Can a PoE injector be used to power a Gigabit switch?
A PoE injector cannot be used to power a Gigabit switch unless the switch has a port to allow for PoE power.
How do PoE injectors save money?
There are four significant ways that the purchase and deployment of a PoE injector will save you money:
- The biggest money saver is that IT pros can combine legacy devices with newer PoE technology through a PoE injector.
- PoE injectors enable organizations to add remote devices to their network without having to install electrical outlets.
- PoE injectors are easy to install and will not require the expense of an electrician.
- PoE injectors themselves are inexpensive, especially when compared to the cost of a PoE switch.
Building and maintaining a business network has many challenges. So it always makes sense to consider power over Ethernet (PoE) technology’s simple, straightforward solution to meet these challenges. This article will discuss one of the key pieces of PoE equipment: the PoE injector. But first, let’s talk a bit about PoE technology itself.
PoE allows a single network Ethernet cable to transmit both data and power simultaneously. This remarkable technology solves some of networking’s most significant issues by:
- Eliminating half of the wires needed by a traditional AC power installation
- Enabling powered devices (PDs) to be installed in locations where there are no electrical outlets
- Eliminating the need for professional electricians during installation.
What is PoE Technology
PoE technology sends 10/100/1000 megabits per second (Mbps) of data and 15.4 watts (W), 30W, 60W, and 100W of power to PDs over Category (Cat) 5e, Cat6, Cat6a, Cat7, and Cat8 Ethernet cables for a maximum distance of 100 meters (m). In addition, this technology adheres to the Institute of Electrical and Electronics Engineers (IEEE) 802.3af, 802.3at, and 802.3bt standards.
PoE-capable devices can be power sourcing equipment (PSE), PDs, or sometimes both. The whole thing works like this: A PSE transmits the power and data while the PD receives the power and data. A few examples of PDs include IP cameras, wireless access points (WAPs), and VoIP phones. Devices such as switches, hubs, and injectors are examples of PSEs. The subject of this article, the PoE injector, is a PSE.
What is A PoE Injector
When a business or other organization decides to adopt PoE technology into their network, many have existing non-PoE switches already in place. And while PoE-compatible switches do indeed exist, in many cases, the purchase and utilization of a PoE injector are more economical and practical.
PoE injectors (also called midspan or PoE adapter) enable a non-PoE switch to work with PoE devices over a single Ethernet cable. They are a perfect solution for low-power devices tucked away in out-of-the-way places where no electrical outlets are available.
Why Use a PoE Injector?
The four significant benefits of the PoE injector are:
- Easy installation: All you have to do is connect the PoE injector to the PoE device and the Ethernet switch.
- Flexible network expansion: PoE injectors add PoE technology to non-PoE Ethernet switches, thus extending the network connection distance.
- Minimal cost: PoE injectors enable the use of existing equipment and cabling, minimizing the expense.
- In general, PoE technology is more reliable and guarantees continuous power delivery.
HOW MUCH POWER CAN A POE INJECTOR PROVIDE
IEEE-compliant PoE injectors can supply from 12.95W to 71W of power to the PD.
PoE Standard PoE Name Power Output Power to the PD
IEEE 802.3af PoE 15.40W 12.95 W
IEEE 802.3at PoE+ 30W 25.5W
IEEE 802.3bt P0E++ 60W 51W
IEEE 802.3bt Hi-PoE 100W 71W
WHAT KIND OF CABLE DOES A POE INJECTOR NEED
PoE injectors are based on the IEEE 802.3 working group and, as such, do not need special cabling. However, please note that IEEE 802.3bt (PoE++ and Hi-PoE) require 8-pin cabling. Nearly all networking cable is 8-pin; however, some very cheap cables on the market only come in 4-pin.
PoE IEEE Minimum Cable Pins Required Supported Modes
802.3af (PoE) Cat 3 4-pins/2-pairs Mode A, Mode B
802.3at (PoE+) Cat 5 4-pins/2-pairs Mode A, Mode B
Type 3 (PoE++)
802.3bt Cat 5 8-pins/4-pairs 4-pair
Type 4 (Hi-PoE)
802.3bt Cat 5 8-pins/4-pairs 4-pair
The use of Cat5e cable or higher is highly recommended, with Cat6a cable being the best for Hi-PoE’s 100W power. Also, 100 percent copper cabling is the safest and most reliable selection for PoE applications.
How Does a PoE Injector Work?
When an organization has an existing Ethernet switch with no PoE capabilities but needs to support PoE-enabled PDs (like PoE IP cameras, PoE LED lighting, etc.), a PoE injector is a low-cost, easy solution that does not involve purchasing an expensive new PoE switch.
To set up a PoE injector, you will need three devices:
- A connection to the network (e.g., a switch)
- The PD (e.g., IP camera)
- The Poe Injector
In most cases, PoE injectors have two RF45 ports: a Data In port and a PoE/Data Out port. Let’s look at these a bit more closely using an IP camera as an example:
Data In Port
The Data In Port connects the IP camera to the local area network (LAN), the Network Video Recorder (NVR) camera port, or a network switch. Without this connection, the network is unreachable.
PoE/Data Out Port
The PoE/Data Out port has two tasks:
- To deliver power to the IP camera
- To complete the network, data is successfully transmitted.
Without this connection, the IP camera will not power up or connect to the NVR/network.
Types of PoE Injectors
Active PoE Injector
PoE injectors that conform to IEEE 802.3af/at/bt standards are considered “active.” This means that if a PD does not provide the proper acknowledgment to the PoE injector during their initial handshake, the PD will not be powered up. This function serves as a safety measure that assures the PD will not be damaged. IEEE 802.3af/at/bt PoE voltage will always lie between 44 to 57 volts (V) DC.
Passive PoE Injector
Passive PoE injectors adopt PoE technology that does not conform to IEEE 802.3af/at/bt standards. Usually, passive PoE injectors run at 18V to 48V DC. If the wrong voltage is utilized, it could cause permanent damage to the PD.
12V vs. 24V vs. 48V PoE Injector
PoE injectors are typically offered in 12V, 24V, and 48V models that indicate the output power voltage they supply. Therefore, it is critical to consider what voltage standard the PoE PD requires when choosing a PoE injector.
How Is a PoE Injector Installed?
As a review: PoE injectors send data while providing PoE technology to PoE-compliant PDs that adhere to PoE, PoE+, PoE++, and Hi-PoE standards. They function as an intermediary that connects a non-PoE switch to a PoE-compliant PD.
Again using our example of an IP camera, here is how the system is put together:
- The items you will need are an IP camera, a PoE injector, a standard network switch, and Cat5e, Cat6, or Cat6a Ethernet patch cables.
- Test all equipment to make sure everything works. Be sure to complete all video and network configurations before mounting the camera.
- Mount the IP camera.
- Plug the PoE injector into an electrical outlet. (A 110*220V AC cord comes with the PoE injector at the time of purchase.)
- Connect one end of an Ethernet cable to the PoE injector’s “PoE/Data Out” port. (Note: these ports are labeled differently from manufacturer to manufacturer. Check the manual to be sure you know which port is which.)
- Connect the other end of the same cable to the pigtail connector on the IP camera.
- Connect a second Ethernet cable to the PoE injector’s “Data In” port.
- Connect the other end of this second cable into an Ethernet port on the NVR, router, or computer.
What Is The Difference Between a PoE Injector and a PoE Switch?
There is often confusion between PoE injectors and PoE switches. This is because they both are commonly used in networks, and their distinctions become blurry.
What is a PoE switch?
A switch is a device that enables a network to communicate. A PoE switch has a built-in injector that allows it to use Power over Ethernet technology. PoE switches conform to IEEEaf/at/bt standards. They are managed and can automatically determine if the PDs on a network is PoE compatible.
PoE switches usually have eight or more copper and fiber networks ports, making them compatible for both or blended networks.
PoE switches work best for networks with a large amount of PDs.
How is a PoE injector different?
PoE injectors play more of a supplementary networking role. They connect a non-PoE switch to PoE-compatible PDs in a network. They are cheaper than PoE switches and are an ideal solution for a network with only a few PDs.
How do a PoE injector and a PoE switch compare to each other?
- PoE injectors are quick, easy, and inexpensive to install, while a PoE switch is a more expensive, longer-term, and more scalable solution.
- As stated above, PoE injectors are much less expensive; however, depending on use and network expansion needs, a PoE switch could be the most cost-effective solution in the long run.
- In networks where power outages are an issue, PoE injectors are the best choice. Here’s why: Many devices are connected to a PoE Switch. Therefore, if a power outage occurs, all PDs will stop working. Whereas, with a PoE injector, only one connected device will be impacted.
- Should a network issue crop up with a PoE switch, it will take some time to troubleshoot, leading to costly downtime. With a PoE injector, only the injector may need to be replaced.
- Bottom Line: Even with all of the advantages inherent with PoE injectors, PoE switches are always recommended for large, complex networks.