What is Power over Ethernet (PoE)?

Normally, a connector cable serves a singular purpose of either transferring data from a data source or transfer power from a power source. However, this is an exception for Power over Ethernet (PoE) as it is able to do both! With the advancement of technology, PoE technology is constantly brought to new heights with more power being able to be provided by a single ethernet cable, while also transferring data!

In this article, I will be going through what is PoE and more:

  • What is Power over Ethernet (PoE)?
  • Why use PoE to power your devices?
  • Different Types of PoE Standards
  • Use Cases of PoE Applications

What is Power over Ethernet (PoE)?

By definition Power over Ethernet (POE) is a technology that lets ethernet cables carry electrical power. Here is a scenario to make it clearer!

In a non-PoE scenario, a powered device (PD) such as a telephone is powered with another connector such as a DC connection while another ethernet cable connects it to the network. If PoE is implemented, the PD, telephone, will be powered and connected to the network via a single ethernet cable! 

How did PoE come about?

Power over Ethernet was originally invented for VoIP phones, phones that use the internet to place and transmit phone calls. VoIP phones when first invented requires a separate power cable for power and ethernet cable for the network. However, Cisco wanted to power and provide network connection via a singular connection, like traditional telephones.

In the year 2000, Cisco Inline Power was invented, the first variation of PoE. Cat 5 ethernet cable and the variations before had 4 twisted pairs of cable with two of them being not in use for data transfer. Cisco used the two unused twisted pairs to provide power!

Three years later, a co-working of Cisco and IEEE brought along the 802.3af (PoE) standard. It is also known as the “Type 1” PoE standard! With that, more companies started harnessing PoE technology as well with more new products being PoE powered. As the technology advances over the year, there are more variations of PoE Standards which will be explained more in details! 

Why use PoE to power your devices?

The main feature of PoE is that data and power may be sent over a single Cat 5 or Cat 6 ethernet cable. Companies are deploying it as there are several benefits that come along with it!

Easier and Cheaper Installation

Normally, the installation of network equipment in a big building requires network engineers and electrical engineers to run the different network lines and power lines in the infrastructure. With PoE technology, network engineers are able to install the network equipment and power them with ethernet cables, saving the costs and valuable time of hiring qualified electricians.

Safety and Reliability

PoE is a safer alternative as compared to the traditional non-PoE route. PoE is designed to protect network equipment from electrical overloading and under-powering, which makes the circuitry safer and more reliable in the long run! 

Furthermore, in an industrial setting, PoE power comes from a central and universally compatible source, rather than a bunch of wall power adapters, which means there are lesser points of disruption. It can therefore be easily backed up by an uninterruptible power supply (UPS) to continue providing power to the network equipment in the event of a power shortage!

Easier Maintenance and Upgrade

As PoE eliminates the requirement for connected electrical outlets, equipment like security IP cameras and wireless access points can be positioned and repositioned more readily. With that, future maintenance and upgrades for the network equipment can be accessed more readily by your maintenance crew!

P.S. In terms of non-industrial usage, where PoE provides the most benefit is where power outlets are not nearby or when multiple devices need to be individually powered! It is also more energy-efficient, being able to intelligently deliver power to match the needs of the device!

Different Types of PoE Standards

The two main types of PoE are “Active PoE” and “Passive PoE”. Active PoE means that the powered device is following PoE Standards which will be illustrated in this section. Active PoE allows the powered device to communicate with the power source to determine how much power is needed to power it. If it doesn’t meet the requirement, it will not power up.

There are currently four types of PoE, with two being the more common ones used in most PoE powered devices. 

NameIEEE StandardMax. Power per PortEnergized Pairs
PoE (Type 1)IEEE 802.3af15.4 W2-pair
PoE+ (Type 2)IEEE 802.3at30 W2-pair
PoE++ (Type 3)IEEE 802.3bt 60 W4-pair
PoE++ (Type 4)IEEE 802.3bt100 W4-pair

PoE (Type 1)

As mentioned, this is the first official IEEE PoE Standard released in 2003. This is the second most common standard used in PoE powered devices. Despite its age, it’s still used in many lower-powered devices. Some of its supported devices are static surveillance cameras, VoIP phones, and wireless access points.

PoE+ (Type 2)

This is the second PoE standard released in 2009, and it is the most common standard used in PoE powered devices. Its main difference is the double amount of wattage per port. It can be used to power more devices such as PTZ cameras capable of pan and tilt, video IP phones, and alarm systems.

PoE++ (Type 3)

The third PoE Standard was released in 2011. It can provide up to 60W of power with four energized pair used. This allows it PoE to power even more devices such as multi-radio access points and video conferencing equipment. It can be even used to power another PoE switch with ports for even more PoE devices! 

PoE++ (Type 4)

The fourth PoE standard was released in 2018. It can provide up to 1000W of power with four energized pair used. This further allows PoE to power even small computers, laptops, and even building lighting and HVAC systems! This standard paved the way for more advanced yet easier to install smart building systems.

What about Passive PoE?

As mentioned, Passive PoE refers to any device not using a PoE standard. Passive PoE devices will not communicate with the power source to determine the amount of power required, there will always be a constant 24W power provided to the PoE powered device. 

There are several risks associated with passive PoE. Imagine plugging an appliance that requires 120V of power into a 240V outlet, your appliance will burn out or even catch fire! 

Despite the shortcomings of Passive PoE, major brands still support Passive PoE as there is a minority of devices that do not support the PoE standards. However, it is predicted to be phased out!

Use Cases of PoE Applications

PoE has been around for many years, yet it is still used in many new applications! Its benefits far outweigh the limited shortcoming it has, if any, that attracts many companies to implement it. 

In this section, I’ll explain the more common uses of PoE technology.

Telephones and Wireless Access Points in Smart Buildings

As mentioned, VoIP telephones strive for the invention of PoE Technology. Telephones and Wireless Access Points are perhaps the most common use of PoE technology due to their simplicity in installation. For example, a new office building is erected with many different levels with many partitions. Telephones and wireless access points are needed on almost every single rooms at each level for communication and access to the internet. 

Source: Router Switch Blog

By powering them with a separate power connector and connecting them to the network with another, each telephone and wireless access points require two cables to be plugged in. However, by powering them with PoE technology over a single ethernet cable, the amount of cable is essentially halved, which means halved the cabling is required to be managed while implemented the telephones and wireless access points. Imagine the convenience and the cost saved!

Besides telephones and wireless access points, there are also many other several devices that are powered by PoE technology in a smart building!

Security and Surveillance Systems

PoE technology second most common usage is in security and surveillance systems. PoE cameras are a common kind of security cameras that is powered by PoE for their simplicity.

Source: Reolink Support

In a PoE security and surveillance system, the PoE cameras are connected to a PoE switch which is then connected to a Network Video Recorder (NVR). The NVR works like a DVR, to collect, manage and record the footage that the security cameras collect. Some NVR allows the PoE camera to be directly plugged into them, eliminating the need for a PoE switch. With that, only NVR and PoE cameras are required and you have yourself a whole security and surveillance system! This simplicity draws in many users to opt for PoE security and surveillance systems instead.

Besides the ease of installation, PoE cameras also have better image quality as compared to wireless cameras, making them the most popular security cameras type!

Fully PoE Powered Building, The Sinclair Hotel

The Sinclair Hotel is a hotel in Texas, USA that fully powers its lights, smart mirrors, minibars, and window shades with PoE technology! The drive for this implementation is due to past negative experiences with the traditional non-PoE lighting systems, where there are many difficulties in getting it to work long-term. 

Source: Hotel News Now

With PoE technology, more than 2000 lights and amenities are powered and connected to a computer network. If a light or any PoE device is disconnected, it will be alerted through an immediate notification on the computer. This PoE implemented reduced the building’s energy consumption by up to 40%, greatly saving costs! It is also connected to an uninterruptible power supply for constant power in the event of a power shortage.

Development Boards

Development boards such as Arduino and Raspberry Pi are starting to support PoE technology. There are many advantages to using PoE technology to power these boards such as the added flexibility, safety features, and centralized control features. Devices power can be managed from a centralized switch.

The Raspberry Pi has released a new hat that allows Raspberry Pis newest release Pi 4 and 3B+ to be powered by PoE+ technology, delivering up to 30W of power at 5V! There are also various other accessories for other variations of the Raspberry Pis and Arduinos to be powered by PoE technology, to harness the advantages it gives!

Enable PoE Capability for your Device, find Hardware at Seeed!

Here at Seeed, we provide various PoE devices and attachments for you to explore the capability of PoE for yourself! In this section, I will teach you how to get started with using PoE for your devices and recommend some hardware to give you a headstart!

First off, here are some PoE attachments and devices available at Seeed!

Raspberry Pi PoE+ HAT for Raspberry Pi 4B/3B+

The all new Raspberry Pi PoE+ HAT is an add-on board for Raspberry Pi computers with PoE connections, such as the Raspberry Pi 3B+ and 4 models. If power-sourcing equipment is deployed on the Ethernet network, it can be utilized to power Raspberry Pi via an Ethernet cable!

The Raspberry Pi processor is cooled by a built-in controlled brushless fan that can generate 2.2 CFM and supports the 802.3at PoE standard with a high output power of 5V DC/4A. For improved power efficiency, it also has a fully isolated switched-mode power supply!

Product Features:

  • Supports 802.3at PoE standard with a high output power of 5V DC/4A
  • Built-in controllable brushless fan delivering 2.2 CFM for better heat dissipation
  • Fully isolated switched-mode power supply for better power efficiency
  • Compatible with Raspberry Pi 4B/3B+

Get one for yourself at Seeed’s online store!

Power-Over-Ethernet (PoE) HAT for Raspberry Pi 4B/3B+

The Raspberry Pi 4B/3B+ Power-Over-Ethernet (PoE) HAT is a Raspberry Pi HAT that can enable PoE for your Raspberry Pi 4B/3B+. This Raspberry Pi PoE Hat supports active PoE, including IEEE 802.3af and 802.3at PoE standard protocols!

Product Features:

  • Easy to assemble
  • Compatible With: Raspberry Pi 4 Model B / Raspberry Pi 3 Model B+
  • Built-in Cooling Fan
  • Support IEEE 802.3af or 802.3at PoE standard

If you like it, visit Seeed’s online store to get one for yourself!

Squama Ethernet – Arduino W5500 Ethernet Board with PoE

Squama Ethernet combines a high-performance Cortex M0+ microcontroller with an Ethernet control chip W5500, allowing customers to create Ethernet applications. On the board, there are also WS2812 LEDs and user buttons, which can help with interaction. PoE (Power Over Ethernet) is supported by Squama Ethernet, making wiring more compact. Arduino IDE is also supported for easier application development!

Product Features:

  • Powerful CPU: ARM Cortex-M0+ MCU running at up to 48MHz (ATSAMD21G18)
  • Flexible power manual: PoE or Type-C
  • Various Hardwired TCP/IP Protocols support: TCP, UDP, ICMP, IPv4, ARP, IGMP, PPPoE
  • Flexible compatibility: Compatible with Arduino IDE

Get one for yourself at Seeed’s online store!

Now that you got your devices down for your PoE implementation, you will need a power source for them to have power!

Power Sourcing Equipment

You will need power sourcing equipment to allow power to flow through your ethernet cable to your device. There are three types of power sourcing equipment, a PoE Injector, a PoE midspan, and a PoE Switch.

PoE Injector

Source: Amazon

A PoE injector allows you to connect it to your router/wireless access point. You then connect the PoE injector to your PoE powered device with another ethernet cable. A PoE injector will allow you to power a single PoE device but if you want to power more than one device, you will need a PoE midspan!

PoE Midspan

Source: Davis Instruments

A PoE Midspan resembles a PoE injector but with multiple ports instead! It comes in various sizes, where the bigger one even allows you to power up to 24 PoE devices! A PoE Midspan works the same way as an injector, where you connect several ethernet cables to your router/wireless access point to the different ports and connect it to the PoE device with several other ethernet cables. Each PoE device will have its own IP address and be supplied with power. 

PoE Switch

Source: Amazon

A PoE Switch works similarly to a network splitter with the added ability to power PoE devices. Instead of connecting different ethernet cables to different ports in the router/wireless access point, you can connect a single ethernet cable to it, and then connect it to your PoE devices, eliminating the need for excess ethernet cables to connect it to the router/wireless access point. It generally costs more than a PoE injector or midspan for the same amount of PoE devices supported.


Power over Ethernet (PoE) is a big trend in recent years, with its many benefits! I hope this article shed some light on how powering devices with your PoE will be beneficial for you, with the costs saved and ease of use! There are many different products to get you into harnessing the power of powering via PoE, but these products will get you started in a pinch!

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June 2021