Unlocking the power of PoE

PoE seems like an obvious powering method in any installation, carrying so many flexibility, safety, and practical benefits. So why are more integrators not using it? Amy Wallington investigates.

Power over Ethernet (PoE), simply put, is the method of powering something through a network cable rather than a power cable. By adding a PoE switch or an injector, installers can power a multitude of home technology devices much easier and quicker, saving time and money as well as adding flexibility to the install.

Network cables, such as Cat5 and 6, comprise of eight cables twisted into four pairs. In 10 and 100BASE-T ethernet, only two pairs are used to carry data, each pair carrying a signal in one direction. The other two pairs are unused and are referred to as the spare pairs.

To carry power over a cable, two conductors are needed because electricity flows in a loop. PoE treats each pair as a single conductor and can carry electrical currents using either the data pairs or the spare pairs.

However, PoE cannot be used for everything; there are still many applications that are not PoE-compatible as they require too much power, but some of the uses in home installations are for CCTV, wireless access points, IP cameras, VoIP phones, local controllers and touch panels, and much more.

Network cables have four twisted pairs – two data pairs and two spare pairs. Zakhar Mar / Shutterstock.com

Adoption

The technology has seen much greater adoption in the professional AV and IT worlds but is much less common in the residential market and typically only seen in very high-end electronics.

“PoE as a technology brings a convenience factor to every installation,” says Andy Herron, product development manager at WyreStorm. “As we continue further into a connected world, more and more devices exist on a network. Practically every smart home device has an ethernet port, so why not utilise that port for more than just data communication?”

He continues: “We can look at the ethernet cable in the same way as USB-C. USB-C has seen an enormous adoption rate over the past two to three years. But why is that? It is because it is a single cable that serves multiple purposes. Power, data, audio, and video can be transmitted over one connection. The same can be applied to an ethernet cable. Traditionally, ethernet has been used for data communication, but it can be used for so much more. Imagine installing electronics using one cable instead of three!”

Generally speaking, commercial projects are usually at a much larger scale than residential and there is usually more budget dedicated to them so it’s not surprising that PoE is used more in commercial projects. But residential integrators are starting to realise the many benefits of introducing this technology into home projects.

“It makes the installation easier, neater and, ultimately, having power and ethernet down one cable means less cables to run around the property,” states Andy Collens, director of iSecure. “It gives the end client a simplified plug-and-play look. And also, you have the ability to utilise spare ports on PoE compatible data switches and the ability to deploy equipment anywhere on the network.”

PoE gives installers much more flexibility in projects, as they are not tethered to an electrical outlet, meaning that devices can be placed wherever they are needed and repositioned easily if required.

Angus Murray, projects director at New Wave AV highlights PoE’s increased reliability: “There is less reliance on unreliable power supplies. It also allows installers to reboot devices remotely when suitable managed network switches have been specified and installed.”

Herron adds: “Traditionally, electronics require multiple connections, one for power, another for internet, and a third for AV. By using PoE, you remove the need for a connection and by doing this you also remove potential points of failure.”

This can also serve as a negative to the use of PoE, but we will come to that later. With the power coming from a central and universally compatible source, it eliminates the need for distributed wall adaptors which obviously saves time and money.

As Collens says: “Take CCTV for example: prior to PoE, you would have to run two cables – one for video and one for power – to each camera position, or power it locally. This could then provide even further problems with electrical interference. Utilising PoE allows you to run just one cable for power and video and this then negates the need for power supplies.”

It also saves time and money by not needing electrical power cabling installed by a qualified electrician. Network cables can be installed by the integrator and can be located anywhere.

IP security cameras are common PoE devices. CC Photo Labs / Shutterstock.com

Support

Adding to the multiple benefits already mentioned, PoE also enhances remote monitoring and management. This creates more cost and time savings by preventing site visits.

“PoE significantly improves the remote support that can be offered,” says Murray. “The ability to power reboot a device remotely can often mean a visit is not required. Combined with active monitoring such as Domotz or OVRC, PoE really assists with the support we can offer our clients.”

Michael Southgate, owner of Intelligent Home Systems, adds: “It definitely makes it easier as a piece of equipment could be power cycled from the switch. The switch can also report back if the unit is not on or accessing the network, depending on the remote monitoring and management offered.”

It doesn’t just help in terms of fixing and updating the technology, as Herron explains: “By powering a device via PoE, you have potential access to device statistics. PoE network switches will be able to provide you with a power draw of devices. You can see exactly how many watts a particular device is consuming. This can be a great resource for troubleshooting to see if a device is under or over consuming power.

“PoE can also allow you to remotely reboot a device that you would traditionally not be able to. You can very easily power cycle an ethernet port on a switch to force a reboot of peripheral equipment.”

Ruslan Khismatov / Shutterstock.com

Downfalls

As mentioned earlier, one of the benefits of using PoE is being able to use just one connection rather than several. This, however, can also be a disadvantage. Herron points out: “Because PoE can consolidate multiple connections, it then means that there is a central point of failure. If the device providing PoE fails, then the devices receiving PoE will also lose power.”

For this reason, many integrators like to ensure that critical devices such as burglar alarms are connected to a mains power source.

“There are some cases where using PoE might not be best suited,” Herron continues. “An example would be security systems. If a PoE power source fails in a system, you will want to make sure that core smart home devices, such as security cameras, stay operational. In this case, it’s best to have them connected to a local mains power source, including a battery backup.”

Other negatives include cost. Collens discloses: “PoE switches do cost more than standard non-PoE switches. And the client has to have the data cabling already if they want to employ the use of PoE devices.”

Misconceptions

Although not new, PoE is a recently developed technology, and some installers are put off from adopting it, often due to some common misconceptions. Like anything, PoE does carry its downfalls, and some prefer to stick to more traditional powering methods.

Many of these misconceptions have been set straight through the IEEE (Institute of Electrical and Electronics Engineers) 802.3xx standards, giving installers more confidence to use PoE.

A surprisingly common misconception is that power is forced into devices. The power ratings stipulated by manufacturers are upper limits and not fixed, meaning that excess power from an injector will not be lost when plugging in a device that requires less wattage. The end device simply draws as much power as it needs to operate.

However, it is worth taking note of, as Murray suggests: “You need to be aware of the PoE budget of the switch. If certain products are mission critical, then you should consider splitting it over more than one switch.”

Southgate agrees, saying: “Installers need to do proper research to prevent having incorrect switches with incorrect power budgets.”

Asharkyu / Shutterstock.com

Changing ways

While it is unlikely an entire smart home will ever be powered through PoE, the list of compatible devices is certainly growing, and adoption is also increasing.

“There will always be devices that are unlikely to use PoE,” Herron continues. “Devices that require a lot of power – network switches, amplifiers, some AV distribution products – will usually require a dedicated AC or DC power supply.”

In Murray’s opinion: “There are lots of elements within a smart home that still require mains voltage. One element is lighting control, and specifically keypads which are typically on a 24V or 48V loop. There is no doubt, though, that the applications are going to continue growing. More devices are low voltage so the move to PoE makes sense. One area of growth that is interesting is the potential for PoE lighting which would allow each individual fitting to be independently addressable and controlled.”

PoE is certainly a technology to keep an eye on and something that will most definitely gain even more traction in residential projects.

Main image: Virrage Images / Shutterstock.com