Building the future with PoE++
The rollout of the IoT is accelerating, but are telecommunications cabling standards keeping pace? Ross McGravie looks at proposed enhancements to PoE standards and the birth of PoE++.
Planning for the future is problematic at the best of times, but the increasing adoption of Internet of Things (IoT) technologies for everyday working and living has literally created a power struggle.
One only has to think of the prevalence of wireless access points (WAPs), networked security cameras, building automation and control systems, and voice-over-IP (VoIP) phones to understand how commonplace it is becoming.
In fact, more than a million devices are already estimated to be connected via Power over Ethernet (PoE) – the system that safely transmits electrical power and data over standard Category 3 and higher-category cabling.
But with the Australian Communications and Media Authority (ACMA) in the process of remaking technical standards relating to customer equipment and cabling, the Australian Digital and Telecommunications Industry Association (ADTIA) has called for upgraded training and greater awareness of the issues from regulators and standards bodies.
More specifically, ACMA is proposing to adopt the 2015 AS/NZS 60950 Information technology equipment – Safety General requirements and the 2018 AS/NZS 62368 Audio/video, information and communication technology equipment – Safety requirements industry Standards. The draft Telecommunications (Customer Equipment Safety) Technical Standard 2018 is expected to have a four-year transition window for compliance.
On a practical level, ADTIA secretary Dominic Schipano says some of the older network cabling in Australian workplaces and homes was not rated for the data and power requirements of IoT and PoE, while technicians with older qualifications may require retraining to be fully aware of the safety and performance issues.
How it works
PoE is designed so that Ethernet data and power signals do not interfere with each other. It works by converting the mains power supply into a low-voltage supply (with inevitable power dissipation), then transmitting the power over structured cabling to PoE-enabled devices.
The power sourcing equipment (PSE) is typically designed as end-span (built into an Ethernet switch port) or mid-span power supplies to the powered device (PD).
The simple nature of PoE has allowed network managers, installers and integrators to use structured cabling to provide power and data to many of their network devices. But as the demand grows, so does the need for more power from the cabling.
The original PoE Standard from 2003 limited the technology to devices requiring less than 12.9W of power. By 2009, the revised standard increased the power supply to 25.5W. And the third incarnation by the Institute of Electrical and Electronics Engineers (IEEE) currently in the pipeline, IEEE P802.3bt, intends to deliver at least 71.3W to PoE-enabled devices, assuming a 100m channel.
CommScope’s 2017 white paper, Laying the groundwork for a new level of Power over Ethernet, says the infrastructure for the IEEE 802.3bt Standard – commonly referred to as PoE++ or 4 Pair PoE (4PPoE) – must deliver more power, increase efficiency and provide support for 2.5Gbps, 5Gbps and 10Gbps connections.
And with some devices, such as IEEE 802.11ac WAPs, expected to exceed gigabit Ethernet capabilities, the Standards will also need to adapt for PoE on higher bandwidth links, such as 2.5GBase-T, 5GBase-T and 10GBase-T.
Parameters set, the IEEE 802.3bt Task Force was charged with creating a four-pair PoE standard that will include a pair-to-pair resistance unbalance specification of about 7%, which allows the use of most of the installed base of Cat5e and better cabling. But considerations include the overall network and channel requirements, effects on thermal and capacity limitations, and cabling and deployment strategies.
Turning old into new
The changes all sound fantastic on paper but the issue remains that legacy telecommunications building cabling usually has not been rated for the proposed power changes to PoE standards.
The result is that older cables, when installed in bundles, heat up more with greater wattage and suffer performance degradation.
“As the heat goes up, performance goes down,” Dominic says.
“But cables with higher categories, such as Cat6A, have larger conductors (and can carry more current) and will heat less than Cat6 and Cat5e. We are not really talking about potential fires, but slower throughput of data. There are other issues like sparking (arcing) that are also an issue at 90W, resulting in a pitting of contacts on the RJ45 outlets.”
In theory, Cat5 is no longer fit for purpose due to the potential of future overload. But the commercial reality is somewhat different.
“Business clients are usually more interested in cost factors – and that it works – rather than technical details. So they will often be unaware of the risks involved, particularly when using older (existing) cable never intended for the higher power transfer with PoE,” Dominic says.
To ensure businesses do not have to replace their entire network of cabling, Panduit outlined a series of recommendations in its 2016 paper, Effect of Next Generation 100W Power over Ethernet on RJ45 Connectivity.
They included: ensuring ambient temperature plus cable bundle temperature rise does not exceed cable operating temperature; ensuring connectivity can meet applicable standards to prevent arcing damage to critical mating area; limiting bundle sizes to ensure temperature rise is 15°C or lower; and using Cat6A cabling for new installations for future proofing.
Likewise, CommScope recommends Cat6A cabling be used to improve thermal performance and energy efficiency while minimising the cost of moves and upgrades – preferably using a zone cabling architecture. To accommodate future capacity upgrades, it is also suggested that network managers plan for at least two runs of Cat6A cabling per powered device to each zone distributor.
International Copper Association Australia technical consultant Ian Millner says the redesign of modular plug jacks has largely overcome sparking (arcing) issues. But educating cablers about the safe supply of power through telecommunications cabling under the new safety standards remains a major hurdle.
“We have three energy sources to find: ES1, ES2 and now ES3, which is classified as any energy source that can potentially cause damage to property and people. ES1 and 2 are intrinsically safe. ES3 is where there are no limits to the current or the voltage being put on telecommunications cabling, so therefore it is up to the manufacturer/installer to ensure that the barriers are in place to ensure the safe deployment of ES3 systems,” Ian says.
“One of the cable manufacturers, Prysmian, actually has VoltServe, which is a technology for digital power. It can deliver a high wattage on telecommunications cabling to provide power to remote wireless access points – and do so even though it’s high power and potentially high voltage. It built it such that if anyone goes across it, they’ll never get any more (of a shock) than touching an electric fence. You’ll know you touched it, but you didn’t die.”
The issue is not new, he says, with Telecom (now Telstra) using technologies in the 1970s and 1980s that were remotely power fed from one end with 300V or higher to power systems in the carrier’s network. The key was that only carrier-trained personnel could access that cabling.
Yearn to learn
Fast forward to the 21st century and the emphasis must shift to educating cablers of the risks they face.
Ian says the ACMA remaking of telco standards and changes to the labelling notice (in relation to safety) was one way in which regulations catch up with the fast-changing technical developments.
“Over the ensuing decade you’ll probably have a growing number of wireless access points to overcome the fact that we’ve got more devices on wireless networks, and wireless networks are moving to higher and higher frequencies, which means they may struggling to penetrate even gyprock walls in the future,” he says.
“Whatever you do, I always tell people nowadays, run Cat6 cable. If you have legacy Cat5, it’ll be fine and serve you for a significant period of time. But if you’re ever in doubt, put the Cat6 cabling in because you can always then connect a WAP where you need it.”
Dominic recommends it become common practice that customers are advised of the wattage capability of whatever cable is installed so that any additional items connected over time consider their power load.
“We also need to jointly develop and update skills options for existing cablers and conduct short appreciation and information sessions for sales and marketers,” he says.