Basic Guide To Power Over Ethernet (PoE)

Basic Guide To Power Over Ethernet (PoE)

Published by Brexons Direct on 12th Oct 2021

What is Power over Ethernet?

PoE allows the transmission of electrical power and data over the same four twisted-pair Ethernet network cables, meaning that only the network connection is needed for a PoE-enabled device, as electrical power is delivered via the same cable.

For example, VOIP phones, IP cameras or wireless access points (WAPs) usually require two connections to operate: An Ethernet network connection for data and a Power connection.

Is Ethernet over Power the same technology? - No! Ethernet over Power enables Ethernet data to be transmitted over mains power cables. Powered devices such as laptops, desktops or other intelligent devices can connect to a network where wireless connections are non-existent or flakey but require separate power.

Benefits of PoE

Power over Ethernet has many benefits:

  • Flexibility - Devices such as WAP’s and IP cameras can be located and relocated as required without needing separate power.
  • Cost-Effective - Network cables and outlets can easily be located anywhere, without the need to have a qualified electrician to fit separate power circuitry at considerable extra cost.
  • Safety - PoE intelligently protects devices from problems such as overloading, underpowering, or incorrect connection.
  • Reliability - PoE power is distributed from a central and standard compatible source rather than various wall power adapters. Also, this source can be backed up by an uninterruptible power supply (UPS) separate from the main power supply and can be set up to reset or switch off devices quickly.
  • Upgradeability - Power being available on the network ensures that additions to the network and distribution of devices are fast, simple and effective.

Devices that use Power over Ethernet

  • VoIP phones – this was the first PoE application - VOIP phones have a single connection via an RJ45 plug lead to an RJ45 jack network outlet, similar to the old analogue phones; they can then be powered up and down remotely.
  • IP cameras - PoE is now commonly rolled out with surveillance cameras, enabling quick deployment.
  • Wireless - WAP’s and RFID access readers are now mostly PoE-compatible, allowing remote location without proximity to or having to lay in AC outlets.
  • Lighting – With the advent of low voltage LED intelligent lighting, it is becoming easy to control lighting levels over an IP network. The control and power to the lights can be managed centrally and delivered safely over a single Ethernet network cable.
  • Security – Access control and proximity readers are readily available.
  • Computers – Increases in available PoE power levels and lowering of power demands of laptops, desktops means many more devices can utilise PoE.
  • Displays – Digital point of sale and audiovisual (AV) displays

Typical Devices That PoE Can Power

IP Cameras
VoIP Phones
Wireless Access Points
Networked Audio

IP Telephones
WiMAX Access
PTZ Cameras
Remote Computer Terminals

Door Access Systems
Video Phones
Thin Clients

Digital Signage Displays
Point-of-Sale Systems
Computer Monitors
Larger TVs
Larger Displays
Larger Monitors

How to upgrade to POE

  • Install a PoE switch which is an Ethernet switch with direct built-in Power over Ethernet. Network devices connect to the switch as usual, and the switch detects if they are PoE compatible; if so, the switch will enable power automatically. PoE switches are available to suit requirements starting from unmanaged desktop switches with a few ports up to multi-port rack-mounted units with or without sophisticated remote control network management.
  • Install a PoE injector (also called a Midspan device) to add PoE capability to standard non-PoE switches. These are particularly useful to provide a solution where just a small number of PoE devices are required. Upgrading a port to PoE is simply a case of connecting the injector to power and patching the injector between the switch port and the device. As with PoE switches, power is delivered if the device is PoE compatible. Midspan Injectors are available as single units with individual power or multi-port rack-mounted units powered from one input to supply all injectors.
  • A PoE splitter makes it possible to upgrade some devices, such as IP cameras or WAP's, to PoE by patching the splitter into the network connection at the device. The splitter splits off the PoE power to inject into the devices power input so that the existing power supply can be discarded. It must be determined in advance that the power delivered to the device is compatible by referral to the device specification.


Care needs to be taken before implementing PoE onto an existing network that the cabling and connectors need to be capable of handling the power levels expected to be used – for instance, Cat6 cable will be more suitable than Cat5e for higher power levels.

Click here for further details on PoE Standards