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What Is Power over Ethernet (PoE)?

by Kevin Bartley

What is Power over Ethernet? Here's a non-technical guide where we break down the ins and outs of this feature and answer some frequently asked questions.

Power over Ethernet is a feature that can streamline setup and decrease the cost of equipment you need to buy for IP-enabled endpoints, such as business VoIP phones, cameras, and other devices that transfer data via Ethernet cables.

If you're unfamiliar with the details of Power over Ethernet, or why you should invest in devices with PoE, we answered some frequently asked questions to better explain the technology and its benefits.

What is Power over Ethernet (PoE)?

Power over Ethernet (PoE) is a way to power devices with an Ethernet cable connected to a Local Area Network (LAN). Instead of using an adapter or outlet to power your device, PoE devices can receive electrical current directly from an Ethernet cable that is connected to a LAN. PoE provides up to 15.4 watts of DC power on each port.

How does Power over Ethernet work?

Ethernet cables can carry electrical current in addition to data, which are sent simultaneously using separate wires. Devices with PoE can therefore receive both power and data from a single Ethernet cable. Devices that do not have PoE only receive data from an Ethernet cable.

An Ethernet injector pushes the electricity into the cable from a switch on the LAN, which is picked up by the device at the other end and routed toward the device's power supply.

When a PoE device is attached to the LAN via an Ethernet cable, the power connection is automatically detected by the switch. If PoE is detected, then power is sent. Conversely, if PoE is not detected, power is not sent.

What devices are compatible with PoE?

PoE has become an increasingly popular feature of IP devices. Many of the SIP deskphones that we review come with PoE. The most popular PoE devices include VoIP phones, IP cameras, and Wireless Access Points (WAPs). Other devices that utilize PoE include:

  • IPTV decoders
  • Network routers
  • Network intercom/paging/public address systems and hallway speaker amplifiers
  • Wall clocks in rooms and hallways
  • Mounted radios
  • LED lighting

If you're unsure about whether a device supports PoE, check the product specifications or ask the manufacturer.

What Ethernet cables should I use for PoE?

Any "Ethernet twisted pair cable" will work with PoE. In other words, any Ethernet cable that you currently have can support PoE. We recommend using a Category 5e (Cat 5e) or Category 6 (Cat 6) cable.

Bloggers at Belden recently made the case that Category 6a cables make the best PoE Ethernet cords.

What is PoE+?

PoE+, or PoE plus, is an updated PoE standard that can provide up to 25.5 W of power, which is roughly twice as much as the original PoE. It makes it easier to perform power cycling (turning a device on and off), diagnostics, and status reporting.

Why can't PoE power my computer?

Standard Power over Ethernet connections do not provide enough power to support devices such as computers, smart TVs, gaming systems, and so on. PoE is ideal for smaller IP devices, such as VoIP phones or security cameras.


What are the benefits of PoE?

PoE has many economic and efficiency benefits for businesses of any size.

  • Less Equipment - With PoE, you need less power cords and electrical outlets to power all your devices. This saves money on AC wiring, outlets, and electrician fees. The ability to schedule device downtime remotely can also save costs on power consumption.
  • Logistical Freedom - With PoE, you can spend less time worrying about the proximity of your devices to electrical outlets. Ethernet cables come in a variety of lengths to accommodate devices in hard-to-reach places.
  • Built-In Precautions - Networking equipment designed with PoE comes with failsafes to protect devices and IP infrastructures. This saves your devices from overloading, under powering, and wrong configurations.
  • Reliable Power - With PoE, power emanates from a single reliable source, ensuring uniformity across devices. This also makes it easier to reset and disable devices.
  • Easy to Scale - The ease of adding and powering PoE devices and networking equipment makes it easier for you to expand your network.

Power Over Ethernet: A Smart IT Choice

Whether you're setting up a cloud phone system, or wiring a security camera cluster, Power over Ethernet can save your business time and money. PoE also adds flexibility to your business's IP network, simplifying logistical issues and decreasing installation times.

And for more of a deep dive on the feature, check out our guide to Power over Ethernet and port speeds.

Learn more about VoIP Fundamentals