PoE in the network: Standards, voltage and types of PoE


PoE, or Power over Ethernet, powers compatible devices on your network using CATx cables. Since you don’t need power cables, PoE saves on materials and installation. This system is particularly flexible, especially for remote installations, since an electrical outlet becomes superfluous. These advantages in particular have made PoE lighting particularly popular in recent years. But power has always been a restriction.

How it works?

It’s pretty simple. CATx Ethernet cable has four twisted pairs. PoE sends power through these pairs to PoE devices. Early PoE standards used two twisted pairs to send data, while the other two used power. Now, PoE allows the transmission of power and data on all four pairs.

When the same two pairs are used for both power and data, the two types of transmission do not generate any interference between them. This is because electricity and data use opposite ends of the frequency spectrum. Electricity uses a base frequency of 60 Hz at most, while data transmissions occur at frequencies of 10 to 100 million Hertz.

What is 802.3at PoE?

The original IEEE 802.3af-2003 PoE standard gives each port with up to 15.4W of DC power. The updated IEEE 802.3at-2009 PoE standard, also known as PoE+ or PoE plus, powers Type 2 devices up to 30W. wire and security cameras in particular. But flat screens, LED lighting or POS terminals need extra power.

Introduction of 802.3bt PoE standard

To meet the higher power demand, the IEEE released a new PoE standard at the end of 2018, to significantly increase capacity. The IEEE 802.3bt makes it possible to generate 60 W to 100 W at the source on the four twisted pairs (instead of the previous technology which used only two pairs). This increase in power will allow PoE to be used on more devices and in different circumstances. In addition, the new standard further reduces energy consumption by halving (advertised value) the losses in the cable.

The new standard will support speeds of 2.5GBASE-T, 5GBASE-T and 10GBASE-T, while the current model allows a maximum speed of 1-Gbps. This new solution will allow an intermediate speed between the existing standards.

PoE types and voltages

Previous PoE technology included PoE Type 1 (or IEEE 802.3af) and PoE Type 2 (or 802.3at/PoE+). Both use 2 pairs. Type 1 allows a maximum power of 15.4 W per port and Type 2 a maximum power of 30 W per port.


The new 802.3bt standard has two new options: Type 3 and Type 4. Type 3 is also referred to as 4-pair PoE, 4P PoE, PoE++, or UPOE. It delivers 60W of power per port and is ideal for video conferencing equipment, multi-radio wireless access points, PTZ cameras and building management devices.

Type 4 (also called “high power PoE”) offers the greatest power, with a maximum value of 100 W in direct current (71.3 W for each device). It is therefore suitable for flat screens and laptops. For more detailed specifications about PoE Type 4 and other types, you can refer to the following table.


Uses and Benefits of PoE

  1. Using twisted pair wires for data and low voltage devices.
  2. In addition to the uses above, PoE is suitable for video surveillance, LED lighting control building management, video kiosks, digital signs, vending machines and business information systems.
  3. Savings since the installation of electric cable becomes superfluous.
  4. Easily move a device with minimal disruption.
  5. If a LAN network is protected against failures with an uninterruptible power supply, the PoE devices attached to your LAN will be protected as well.

PoE Ethernet Switches

PoE Ethernet switches can also power hardware. They inject power into the Ethernet cable to provide power to PoE devices, including access points and security cameras. Learn more about PoE Ethernet switches .

Splitters PoE

PoE splitters receive a PoE signal containing data and power. They separate the data from the power on two different lines to provide support for non-PoE devices. Learn more about PoE splitters .

PoE Repeaters/Extenders

They allow the extension of PoE connections beyond the 100 meter limit to access remote PoE devices such as access points, cameras and VoIP phones. Learn more about PoE Repeaters/Extenders .

PoE media converter

PoE media converters are the perfect way to extend your fiber or copper network while powering PoE devices over long distances. They act as copper/fiber optic converters and power supplies. Learn more about PoE media converters .

PoE injectors

PoE injectors carry data and power over the same Ethernet cable. This type of injector powers various VoIP phones, security cameras, wireless network access points, Bluetooth® access points and other 802.3af compatible equipment. This saves you the expense and work associated with installing power outlets for remote cameras, access points or thin clients. You will also be able to move the equipment from one room to another without going through expensive and tedious wiring work. Learn more about PoE injectors .

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