A Guide to Using Power over Ethernet (PoE)
What PoE is and when to use it to save you time and money
Power over Ethernet (PoE) is an evolving technology that allows a single cable to deliver both electrical power and network communications. It is used for a variety of reasons, such as outfitting smart buildings, and with a range of powered devices, including surveillance cameras and security card readers. Using PoE vs traditional AC power saves the installer time and money and makes for a cleaner, more attractive installation without the use of power cables at the device.
What is PoE technology?
Power over Ethernet is a technology that delivers data and power signals to connected devices through an ethernet cable (Category 5e, Category 6 or Category 6A). PoE can read and write data to and from a device, as well as power the device all with a single cable. In addition to an ethernet cable, PoE requires network equipment that is PoE-enabled.
There are two different ways to enable PoE on a network device, using Power Sourcing Equipment (PSE):
Endspan (PoE switch) - an ethernet switch that has PoE already built in it. This switch can provide power to network devices.
Midspan (PoE injector) - The midspan acts as a "booster" for non-PoE capable switches. This device adds a power source between the network switch and the device.
You can upgrade an existing network connection to PoE using a PoE switch or a midspan PoE injector. A PoE injector can be installed at the non-PoE switch or midspan and injects electric power down the category cable to the device.
How does PoE work?
PoE is used in a variety of systems. If a device is already enabled with PoE, then it only needs the network connection, as the PoE cable will already have power carrying throughout. To know if your network device is compatible with PoE, you will need to connect it to a PoE switch to determine the device's power requirement. The good news: Most applications are PoE compatible due to the increased use of Internet of Things (IoT) used in today's network-connected world. Below are a few different ways powered devices (PDs) implement PoE technology.
What devices can use PoE?
- VoIP phones - The earliest PoE application that lets phones have a sole power source to a wall adapter with the ability to be powered down remotely.
- IP cameras - Security technology is constantly improving, therefore, PoE creates faster deployment and repositioning needed for this type of application.
- Wireless - Most wireless devices are PoE compatible, allowing for more flexibility to move anywhere remotely. For example, RFID readers are PoE-compatible, which means they can be farther away from AC outlets and easily relocated.
Several types of PoE switches
Assembling your first project using PoE technology is easy if you know exactly which type of PoE switch you need. The three types are managed, smart (hybrid) and unmanaged.
- Managed PoE switch - This is used for enterprise networks and data centers. Typically, the managed switch provides 24/7 monitoring (on or off-site), remote control (on or off-site) features and network security.
- Unmanaged PoE switch - Used in home settings or small business offices with fewer than 10 computers. This switch cannot be altered and offers no security features. This is a basic plug-and-play device that is recommended for smaller networks.
- Smart or hybrid PoE switch - Used for smaller applications such as VoIP phones and small virtual local area networks (VLANs). The smart switch lets you set up virtual networks and assemble ports for your project.
What are the benefits of using PoE?
This two-in-one source for connectivity allows the ethernet cable to easily and securely transmit power without the hassle of installation errors. PoE eliminates the use for multiple cables used to connect to powered devices. This reduces the time and money required to install the powered devices. For example, suppose a project calls for five IP security cameras. In that case, the installer only needs to install one Category cable with PoE signals to each of the five cameras rather than installing Category cable plus 240v AC power wiring for power at each camera.
Here are a few reasons why you should use PoE:
- Time savings - Running one cable vs. multiple cables reduces the amount of time to complete your projects.
- Cost savings - Just like saving time, using PoE is cheaper because it uses fewer cables.
- Reliability - Power and data come from one organic single connection instead of a variety of diverse sources or wall sockets.
- Safety - Because PoE devices utilize fewer power sources, the likelihood of overload and equipment damage is decreased, as is the risk for power outages.
Considerations when using PoE
PoE switches not only come in various management types, but they also come in various PoE power budgets. There are various power supplies to choose from when specifying a PoE switch. Understanding the power requirements of the powered devices is important. The installer must consider the total power requirements as well as the individual maximum power on the individual ports on the POE switch.
What kind of network cable can I use with PoE?
Four pair, unshielded twisted pair (UTP) is the desired cable for PoE — specifically, Category 5e and Category 6 are adequate. However, Category 6A is suitable for network speeds up to 10 Gbs per second and has better heat-resistant capabilities to handle present and future high-power PoE applications.
