Power Over Ethernet: Demystified

March 08, 2023 Power Over Ethernet: Demystified

Power over Ethernet (PoE) technology has revolutionised the way we power network devices, providing a convenient and cost-effective solution for powering devices like IP cameras, access points, and VoIP phones to name but a few. With the release of PoE++, also known as 4PPoE (four Pair PoE), the power output has increased significantly to 100W, allowing for the powering of high-powered devices like PTZ cameras, video conferencing systems, and large displays. While Power over Ethernet offers many benefits, it also has its limitations and best practices that should be considered when designing and implementing a Power over Ethernet system. 

Power over Ethernet (PoE) technology has been traditionally used in commercial and industrial settings, where it allows for the deployment of networked devices without the need for additional power outlets. However, in recent years, Power over Ethernet devices have become increasingly popular in the home as well. 

What is Power over Ethernet?

The concept behind Power over Ethernet is to simplify the installation and maintenance of network devices, by eliminating the need for a separate power supply for each device.

The Power over Ethernet technology works by injecting power into the Ethernet cable at the source end using a PoE-compatible switch or injector and then extracting it at the device end. This way, network devices can receive both data and power from the same cable, allowing for greater flexibility in network design and installation.

What are the benefits of Power over Ethernet?

One of the main benefits of using Power over Ethernet devices in the home is their convenience. Power over Ethernet eliminates the need for additional power outlets, making it easier to deploy networked devices in areas where power may be limited. For example, PoE cameras and PoE intercoms can be installed outdoors without the need for an additional power outlet, making them an ideal solution for home security systems. Modern control processor and AV over IP devices often employ Power over Ethernet for combined power and data supply. 

Another advantage of Power over Ethernet devices in the home is their flexibility. Power over Ethernet allows for the deployment of devices in locations where it may be difficult or impossible to run power cables. For example, PoE-enabled lighting fixtures can be installed in areas where running electrical wiring may be challenging, such as ceilings or walls. 

Remote power management of devices is also becoming more relevant and important, and Power over Ethernet technology allows remote power control directly from managed PoE switches. This can allow rebooting of devices to reduce service call outs or be utilised as part of controlled load shedding strategy to reduce energy consumption. 

In addition, Power over Ethernet devices in the home often offer cost savings. By eliminating the need for additional power outlets and associated electrical wiring, the cost of installation can be reduced. Additionally, Power over Ethernet devices are typically more energy-efficient than traditional devices, reducing the cost of operation over time. 

Power over Ethernet Limitations

Power Capacity 

The main limitation of PoE is its power capacity. While PoE++ provides a maximum power supply output of 100W the maximum power that is delivered to the device at the end of the ethernet cable is reduced to 90W, there are still some high-powered devices that may require more power. For example, high-end PTZ cameras with multiple motors and zoom functions can require up to 120 watts of power, which is beyond the maximum power output of PoE++. Similarly, large displays and video walls may require additional power beyond what PoE++ can provide. 

Distance 

The maximum distance that Power over Ethernet can reliably transmit power and data depends on various factors, such as the type and quality of the cable used, the amount of power being transmitted, and the environmental conditions of the installation. 

Generally, and as defined within the specifications, Power over Ethernet can transmit power and data up to a distance of 100 metres (328 feet) over a Cat 5, Cat6 or Cat6A cable. Beyond this distance, the power output may drop, and the data transmission may become unreliable.  

It is essential to consider the distance limitations of PoE when planning network installations to ensure that the equipment is positioned correctly and determine if additional hardware, such as PoE repeaters, is required for longer distances. 

The 7 Best Practices for Power over Ethernet 

When designing and implementing a Power over Ethernet system, there are several best practices that should be followed to ensure reliable and efficient operation. 

  1. Determine Power Requirements 

Before selecting Power over Ethernet equipment, it is important to determine the power requirements of the devices being powered. This will help determine the appropriate power budget and the number of PoE ports needed. High-powered devices like PTZ cameras, video conferencing systems and displays may require additional power beyond what PoE++ can provide, and may require the use of additional power supplies. There are also other important considerations when using PoE switches. The maximum power budget on PoE switches varies depending on the model, with some switches providing up to 740 watts of power. It’s important to select a PoE capable switch with a sufficient power budget to ensure all connected devices receive the necessary power to function properly. It may be necessary to split loads across multiple switches to provide enough power for all the devices in the system. 

  1. Select Compatible Equipment 

When selecting Power over Ethernet equipment, it is important to ensure that the equipment is compatible with the required PoE standard. Not all PoE equipment supports PoE++, and devices that do not support PoE++ will not be able to take advantage of the higher power output. In addition, not all PoE equipment is created equal, and some equipment may have different power budgets and features. It is important to select equipment that meets the specific needs of the network and the devices being powered. The good news is that PoE standard is backward compatible, and switches and PoE injectors capable of PoE++ can readily supply power to earlier implementations of the technology. 

  1. Consider Power Loss 

As mentioned earlier, the power output of Power over Ethernet decreases as the distance increases, which is due to the resistance of the copper in the cables. As a result, devices located at the far end of the cable may not receive enough power to operate. To compensate for power loss, it is important to select PoE equipment with a higher power budget than the devices being powered, and to consider using shorter cables or cable with a larger gauge. 

  1. Use High-Quality Cabling 

The quality of the cabling used in a PoE system can have a significant impact on its performance and reliability. High-quality cabling with low resistance and minimal signal loss can help maximise the power output and reduce the risk of damage to the devices being powered. In addition, it is important to ensure that the cabling is rated for the appropriate power level and distance. 

  1. Monitor Power Consumption 

To ensure that a Power over Ethernet system is operating efficiently and reliably, it is important to monitor power consumption. This can be done using a network management system or by using PoE equipment with built-in power monitoring features. By monitoring power consumption, it is possible to identify potential issues before they become critical, and to optimise power usage to ensure the most efficient operation of the network. 

  1. Protecting Your PoE System & Devices 

Surge protection is crucial when using Power over Ethernet (PoE) devices. PoE devices are vulnerable to power surges and spikes that can cause damage to both the equipment and disrupt the network. This is especially critical when planning a PoE installation that has outdoor cabling. 

Using surge protection devices can prevent costly downtime and protect against electrical surges that could damage sensitive electronic components. It is essential to choose surge protectors specifically designed for PoE devices to ensure optimal performance and protection. Surge protectors should be placed at with end of outdoor cable runs to prevent damage to either the head end equipment or the PoE powered devices. Without surge protection, PoE devices are vulnerable to damage from lightning strikes, power outages, and other electrical disturbances, which can cause data loss, network downtime, and equipment failure. Therefore, using surge protection with PoE devices is essential for ensuring a reliable and robust network. 

  1. Plan for Redundancy 

Finally, it is important to plan for redundancy in a Power over Ethernet system. This can be done by using redundant power supplies or by using multiple Power over Ethernet switches in a redundant configuration. Redundancy can help ensure that the network remains operational in the event of a power supply failure or other issue. In addition, it is important to consider the use of uninterruptible power supplies (UPS) to provide backup power in the event of a power outage. 

Kordz and Power over Ethernet

As you’d expect, all network cables manufactured by Kordz are PoE capable and support the latest PoE++ standards.

Despite their diminutive size at 28AWG, the SlimCat range of network cable is also fully capable of the demands of PoE++. This makes all Kordz network infrastructure products ideal for use in high-demand environments where a greater amount of power is required, allowing customers to use the latest and most advanced PoE technology with ease and confidence.  

A cornerstone of Kordz approach to manufacturing is the use of high-quality materials and advanced manufacturing techniques. This delivers the best possible performance for integrators, whether they are using unterminated cable with associated components or Kordz readymade cable assemblies such as the Cat6 PRO and the Cat6A PRS Patch Cords. It also worth noting that where appropriate, all Kordz cables are certified, allowing Kordz to deliver on its promise of ‘Connectivity. Assured’. You can read our article on Certifications and why they are the future of the AV Industry here.

Conclusion

Power over Ethernet (PoE) technology offers many benefits, including cost-effectiveness, convenience and flexibility. However, it is important to be aware of its limitations and to follow best practices when designing and implementing a PoE system. By considering power requirements, selecting compatible equipment, using high-quality cabling, monitoring power consumption, and planning for redundancy, it is possible to ensure a reliable and efficient PoE system that meets the needs of the network and the devices being powered. As PoE technology continues to evolve, it is likely that new best practices and solutions will emerge, but the fundamental principles of power management and network design will remain important considerations for any PoE implementation. For more information on Kordz products and PoE capabilities, please contact info@kordz.com

Extra Resources

Table PoE Types

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