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What is Power over Ethernet?

Wikipedias states  that PoE (power over Ethernet) is the process where systems send electrical power over the same data cabling as the Ethernet transmission. In this manner the data cabling can send both the data transmission and power to certain devices

Power is injected onto the cable at a voltage between 44 and 57 volts DC, and typically 48 volts is used.

Therefore the voltage is designed and deemed to be safe for users of the equipment. Furthermore if equipment that is not designed to receive PoE transmission is plugged into the transmission lines damage can occur

PoE+

The IEEE 802.3at PoE+ specification incorporated an extension to the original IEEE 802.3af PoE standard.

Firstly this was implemented to provide more power to devices that operate on  PoE transmissions

Secdondly the 802.3af PoE standard provides up to 15.4W of power or 48 volts DC @ 0.32 amps to each device.

Furthermore the maximum power output With PoE+ increases to  25.5 Watts or 48 Volts DC @ 0.52 Amps) when that power is sustained and a peak power limit of 30 Watts or 48Volts DC @ 0.63 Amps)

Power over Ethernet provides an economical answer to our power and data requirements

Over the past decade our lives have become increasingly reliant on a vast array of devices that support and control the environments in which we live and work.

Our way of life is interwoven with technology. Not only in terms of mobile phones and the internet, but also an astounding network of cameras and sensors. These cameras subsequently monitor and regulate the world around us.

This is a trend that is set to continue as the Internet of Things comes of age.

We have sought to centralise much of the infrastructure that manages this technology. Furthermore we have  created networks of environmental sensors, lighting controls and security devices.

Typical applications

The types of devices that are best suited to PoE connectivity remain in a fixed position and have a low power draw.

PoE is particularly useful for connecting disparate and geographically dispersed devices to your network. Furthermore without having to add a separate power source or additional cabling.

Common examples include:

  1. WiFi access points
  2. VOIP telephones
  3. CCTV Cameras
  4. Access Control
  5. Intercomms
  6. Mobile Boosters

 These devices require both power and data connections to function

All of these devices require fixed power sources and data network connectivity to operate effectively. In addition most require a high level of resiliency and are therefore unsuited to battery power, or wireless network connections.

Additionally as you expand your network to include more nodes and user devices, creating separate power and data solutions becomes an arduous and expensive task.

As an alternative, passive power over Ethernet (PoE) patch panels can be used as part of a cost effective solution for distributing power to where it is needed. In addition to offices this includes the home, campus or other environment.

Patch panels are a vital part of an Ethernet cabling solution for organising and managing cable connections. They maximise the effectiveness of the IT cabling by delivering power and data to where it is needed.

While there are other cabling solutions that provide both power and data such as USB, PoE is suitable for far longer distances.

Power over Ethernet Data Cabling

The choice on data cabling will make an impact on the performance of the PoE cabling and its devices. Cat5e and Cat6 can be installed to support PoE devices but the industry consensus is that Cat6a should be the standard for these installations

The following guidelines for Cat6a installations will improve the performance of your PoE devices

  • Avoiding tightly packed cables will increase performance. Cables that are tightly packed together increase the overall heat and heat within each cable. Being tightly packed the heat cannot disperse as easily and performance suffers

Cat6a cables usually have a greater insertion loss margin to handle increased heat that is generally created by cables that are tightly packed together

  • With regards to size Cat6a cables have a greater gauge diameter in their cores and therefore cable size. Therefore reduced resistance and therefore lower temperature when compared to lesser grade cables. Its been determined that in a cat5e cable 20% of power can be lost in transmission
  • As the above mentions the loss in cat5e is less in a cat6a cable. Reducing that 20% loss in power will not only lead to better transmission and operation but also reduced electrical costs to run your systems and devices

 Electromagnetic Interference

To help prevent Electromagnetic interference when using PoE it is important that the patch panel is properly grounded.

This type of disturbance, if not guarded against, can have a serious detrimental effect on performance. Most panels are supplied with a grounding bolt for this purpose.

Long term outlook

PoE patch panels will become an ever more important part of any structured cabling solution. Furthermore it will be required as the plethora of interconnected devices continues to grow.

Finally our environments at work and home become increasingly “smart”. Indeed PoE will emerge as the most dependable and cost effective method of supplying power and data to the network.  Hardware such as cameras, sensors and telecommunications equipment that we have become increasingly reliant on.