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Implementing PoE

by Benchmark

Power over Ethernet is unquestionably one of the more significant cost-saving benefits when networked security solutions are deployed. It offers a simpler and faster installation and is flexible enough to make system reconfigurations an affordable and easy task. PoE also transcends technologies and could be beneficial for those installing any type of security solution. With a growing focus on PoE, there are also a wider variety of providers for installers and integrators.

Much of the labour time associated with any system installation is taken up with cabling. Despite the Benchmark team having spent several decades in the security industry, we still don’t come across many installers or integrators who enjoy pulling cable. Indeed, often any reduction in the amount of cabling is welcomed with opened arms.

Another part of the installation process that’s rarely enjoyed is the addition of fused spurs. While many installers and integrators have trained to allow the fitting of spurs, there are still a number who have to subcontract an electrician to do this job.

Of course, installers and integrators who work with network platform-based systems enjoy two significant benefits: the reduction of cabling and the elimination of a need for dedicated fused spurs. This is in addition to the overall flexibility offered by networked solutions in general.

They say there’s no such thing as a free lunch, but if a system is based on network infrastructure, then there’s certainly a very low cost lunch to had in the form of power over Ethernet (PoE).

Forget PSUs?

When it comes to low power requirements for security systems, there is often an attitude amongst many installers and integrators that traditional power supplies are an effective and low cost option, so there’s little point in looking elsewhere. However, that’s a somewhat blinkered approach and one that might end costing you contracts. Maybe it’s time to forget about PSUs, or at least push them to the back of your mind when designing a solution.

It is true that, typically, PSUs are low cost devices. However, it is important to realise that doesn’t always mean they represent the best value for money. Indeed, when considering their use in many modern security systems, they can often be more costly than you might think. It’s important to assess the total cost of providing low power rather than just the cost of the device.

If you consider the average cost of a PSU, it’s not significant when compared to other components of infrastructure, let alone the security devices making up the system. However, in a typical security solution, the number of PSUs being installed soon starts to multiply, and eventually the power needs of a site can carry a significant cost.

It’s not just the PSUs that impact on the total cost; there’s also the need to have fused spurs located nearby to every device, plus cabling to carry power to the edge equipment. When you add that expenditure, low power can turn out to be anything but low cost.

Where there are remote devices, the provision of traditional low power can become even more expensive. Indeed, often system designs can need to be altered where power provision simply makes a specific device not financially viable.

The costs are then exacerbated if the customer wants (or needs) to relocate a piece of equipment, such as a camera or door controller. There is then a need for an additional fused spur at the new location. The costs are often not only financial; there’s downtime if you’re relying on contracting in an electrician, as well as making good after the spur is fitted. Indeed, sometimes the aggravation of relocating devices can be a strain on profits while making another tradesman some easy money. It’s one of the burdens of keeping customers happy!

However, for installers and integrators using networked-based solutions, a better option exists. There are a wide range of manufacturers providing PoE solutions which are ideal for network-based security solutions!

It must be pointed out that few installers or integrators will migrate of IP-enabled solutions purely to realise the benefits of PoE. However, in many cases (including one integration company that often works with Benchmark on testing), PoE is the benefit that pushes companies into a move that they’ve been contemplating for some time. Whilst the other benefits of networked systems are immense, PoE can change unrealistically priced applications into realistic solutions.

Adding flexibility

Power over Ethernet has become an essential feature or many network-based security devices. Indeed, where equipment that utilises network connectivity doesn’t include PoE, it is often considered as less appealing and typically avoided by forward-think integrators and installers.

Those who have adopted PoE technology will readily and passionately argue that it is a significant benefit when considering the use of IP-enabled systems. Some of the largest systems integrators have told Benchmark that they simply won’t consider devices which don’t offer PoE, because of the flexibility and the economies that the technology offers.

One buyer for a large national installation company reported that considering non-PoE devices, plus the additional cost of traditional power, simply did not make sense for them if they were to be competitive. Finally, the majority of end users questioned about PoE stated they ‘expected’ it to be a feature of networked solutions. It’s not on their wish-list; it’s a ‘must have’ benefit because they understand the associated cost savings.

Power delivery

Whilst PoE is well established in a number of sectors, and is growing in popularity in the electronic security market, misunderstandings about how it works have caused some to debate the suitability of the technology for business critical systems.

There are two main variants when it comes to PoE, with low power (15.4W) and PoE+ (30W+). These are covered by compliance to the IEEE 802.3af and IEEE 802.3at standards.

Whilst PoE is delivered over network links, it’s supply has nothing whatsoever to do with network traffic, nor is it affected by a network’s performance. PoE merely utilises redundant copper cores in standardised network cabling. Power delivery occurs over spare pairs in Cat 5 and Cat 6 Ethernet cables. If the switch injecting the power is live and the physical cable is connected, then the device still receives power. In this respect, it is no different to a PSU.

It is worth making a note about the term ‘injected’. Some people are concerned that PoE effectively forces power into devices. Of course, the terminology is just that, terminology. PoE makes the power available, and devices take the required wattage.

The power is injected into the cable, typically at a PoE-enabled switch or a midspan. The difference between the two is that a midspan sits in the cable run, typically as a rack-mounted item, but does not carry out any switching tasks. It simply adds PoE to the infrastructure.

Where complex network topologies are used with multiple switches, the PoE-enabled devices will be the first switch that the powered edge devices link to. This could therefore be up to 100 metres away from the powered devices. These distances are the limitations of typical IP links. However, the security sector can benefit from a growing number of long reach switch options, and these can support PoE over longer distances. Another benefit of these devices is that they can be used with various cabling options including UTP and legacy coaxial cable.

Often one source can power numerous devices, dependent upon the capacity of the PoE switch or midspan which is being used. It also means that often existing spurs can used, along with power outlets in secure areas. As network racks are typically powered, there will often be no requirement for installers and integrators to add power sources.

PoE switches and midspans are available in a wide range of configurations. These can vary from simple basic PoE injectors that supply a single power link, through Ethernet switches that might support dozens of PoE devices, to industrial rack-mount solutions that can theoretically support unlimited numbers of devices. As network cabling will be run to connect to the device, power is subsequently supplied without any additional cabling.

The flexibility of PoE is made evident by the fact that if a device is moved, it’s network connection must move too. Where PoE is deployed, that also means that the power automatically goes with it. There is no need to ensure that a power supply with associated power source is available at the new location. PoE allows faster system redesigns, upgrades and expansions, often without any need for changes to power provision.

Where devices are deployed on a temporary basis, PoE allows for a very swift installation. It also ensures that there is minimal disruption during the installation, and little sign that a device was installed once it has been removed.

A final point is that PoE doesn’t have to be used solely with PoE-compatible devices. In many cases it is also possible to realise the benefits of PoE technology to simplify the supply to traditional low power devices. There is an opportunity to use splitters at the device end of the Ethernet link. These are devices which effectively extract the power from the network link, and can therefore deliver the low power directly to conventionally powered devices.

In summary

PoE can certainly offer cost savings, and in most applications the technology will be suitable for use with the majority of edge devices. It relies on a physical connection between the midspan or switch and the powered device, so is effectively hard wired. In short, the risks with PoE are the same as with traditional PSUs.

Where the two differ is that PoE delivers significant benefits in terms of cost and flexibility for all parties when designing a network-based security solution. Add to this the emerging long reach switch options, and PoE can even be used for perimeter-type applications.


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