Power Sourcing Equipment for PoE Devices: A Comprehensive Guide

power sourcing equipment

Power over Ethernet (PoE) technology has revolutionized the way networked devices are deployed and managed by combining data transmission and power delivery over a single Ethernet cable. This innovation has simplified installations, reduced costs, and provided greater flexibility in device placement. Central to the success of PoE networks is the Power Sourcing Equipment (PSE). This article provides an in-depth look at PSE, its types, standards, and key considerations for selecting the right PSE for your PoE devices.

What is PoE equipment?

Power over Ethernet (PoE) is a technique for delivering DC power to devices over copper Ethernet cabling, eliminating the need for separate power supplies and outlets.

What is Power Sourcing Equipment (PSE)?

PoE delivers DC electrical power over Ethernet cables to connected network devices. The device delivering the power is called the Power Sourcing Equipment or PSE. PSE devices are responsible for injecting power into the Ethernet cables, allowing connected devices like IP cameras, wireless access points, VoIP phones, and other networked gadgets to operate without needing separate power supplies.

Understanding PoE Standards

PSEs are designed based on IEEE PoE standards, which ensures seamless integration and interoperability when deploying PoE. These standards control the maximum power and voltage specifications. The selected PSEs need to be compliant with the PDs and of the same PoE standards.

IEEE 802.3af (PoE)

Adopted in 2003, IEEE 802.3af is the original PoE standard. It allows for up to 15.4 watts of DC power to be delivered to each device, but due to losses in the cable, the minimum power available on the powered device is 12.95 watts. It is suitable for devices like IP phones and basic IP cameras.

IEE 802.3at (PoE+)

An enhancement to the original PoE standard, IEEE 802.3at was ratified in 2009. It increases the amount of power that can be delivered over a single Ethernet cable to a maximum of 30 watts, with 25.5 watts being the minimum guaranteed power available at the powered device after accounting for cable losses. This is suitable for networks with advanced IP cameras with PTZ features, dual-radio wireless access points, video phones, and other power-intensive devices.

IEEE 802.3bt (PoE++)

The most recent update, ratified in 2018, is further divided into two types — Type 3 and Type 4:

  • Type 3 – Offers up to 55 watts of power supply, potentially allowing for things like more advanced teleconferencing equipment and building management devices to be powered over Ethernet.
  • Type 4 – Delivers up to 100 watts, enabling even more power-intensive applications, such as data center server connectivity or high-performance wireless access points and workstations.

Common POE Power Sourcing Equipment

PoE Switch

PoE switches integrate power sourcing capabilities directly into the network switch. They provide both data and power through their Ethernet ports. PoE switches are ideal for new network installations or when upgrading infrastructure. They come in various port configurations, such as 8, 16, 24, or 48 ports, making them suitable for networks of different sizes.

PoE Media Converter

A PoE media converter not only links fiber cables to a copper network for photoelectric conversion but also supplies power to compatible devices like IP cameras and VoIP phones.

PoE Injectors

PoE injectors are used to add PoE capabilities to non-PoE network switches. They are placed between the switch and the PoE devices, injecting power into the Ethernet cables without interfering with data transmission. PoE injectors are a cost-effective solution for retrofitting existing networks with PoE capabilities.

PoE Extenders

Extenders connect distantly located PD and PSE and extend the transmission distance. There are PoE extenders that facilitate power supply to PD along with data. You need to decide the number of PoE extenders depending on the distance or total length between PSE and PD. Generally, you can install one extender over a distance of 300 feet. However, this device is suitable mainly within similar network type.

Factors to Consider When Choosing POE Power Sourcing Equipment

  • Power Requirements

Identify the power requirements of your PDs. Devices vary significantly in their power needs. For instance, a standard IP phone might require less power compared to a high-end PTZ camera. Ensuring your PSE can deliver adequate power is crucial.

  • Number of devices

Determine the number of PoE-enabled devices you need to connect. A PoE switch with multiple ports is ideal for large deployments, while a single-port PoE injector may suffice for smaller setups.

  • Number of PoE ports

In most blended networks or fiber optic ones, the number of PoE ports is important because of the connectivity between two or more dissimilar networks. Check the port speed, configuration, and type against your requirements. Media converters are a great option as PSEs for blended networks.

  • Power Budget

Check for features in PSEs such as power allocation, prioritizing devices, and power budgeting per port.

  • Compatibility

Check the IEEE PoE compatibility based on the version of PSE and PD. It must be the same to avoid damages and functional issues

  • Future Proofing

Anticipate future growth. Opt for PSEs with higher power budgets and additional ports to accommodate new devices as your network expands.


Selecting the right Power Sourcing Equipment for your PoE devices is essential for building a reliable and efficient network. By understanding the different types of PSE, adhering to PoE standards, and considering factors like power requirements, number of ports, power budget, management capabilities, environmental conditions, and future needs, you can ensure a robust PoE infrastructure that supports your organization’s growth and technological advancements. Investing in the right PSE not only simplifies deployment but also enhances the scalability and functionality of your network.

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