In Steven Covey’s seminal and groundbreaking book, “The Seven Habits of Highly Effective People,” he makes the case that effective use of time, energy and resources are best spent working in Quadrant 2.   Quadrant 2 is characterized by topics that are “Important” but “Not Urgent.” Of note, two of the most important (and relevant) activities that are called for in Quadrant 2 are Prevention and Capability Improvement.

Over the past several weeks, we have written extensively about the growing body of evidence that is showing why proactive, preventative actions will help safeguard the data cables that support PoE applications. The cabling industry will serve its customers best by keeping pace with change. As IoT and connected buildings continue to evolve to “smart buildings,” structured cabling also must evolve to “smart cabling.”

We believe there are three important factors that need to be considered:

• Building owners, IT managers, installation professionals and Authorities Having Jurisdiction (AHJ) need to be able to certify compliance with the National Electric Code (NEC) on day 1 of the installation, and know the installation will remain in compliance on day 2. 
  
• A system for safeguarding structured cabling that supports PoE is needed because, even while the the best information in the IEEE standards and NEC is useful, this alone does not provide  peace-of-mind assurance related to performance optimization and compliance. Installing cables with larger diameter conductors and licensure requirements are insufficient remedies.
  
• Resistance unbalance can occur in cabling networks today, and the industry needs a system for active, on-going measurement and monitoring of this condition.

The Science and Engineering are Real

The growth of PoE enabled devices is evident, with port shipments expected to exceed 624M over the next five years. Not only will the amount of PoE devices increase, so will the number of significantly higher-powered devices.

DC resistance unbalance results in uneven current flow between two conductors within a twisted pair.  Neither the Power Sourcing Equipment (PSE) nor the Powered Device (PD) can detect it since the total current transmitted from and received by the PoE devices is the same. There are many potential sources for DC resistance unbalance, but the reality is simple: It happens, it can be measured, and it can change with physical movement of the conductor in the IDC slot.

This unbalance creates a cascade of consequences:

Temperature rise in the cable can occur → causing the insertion loss of the cabling channel to increase → which triggers a change in the electrical length of the cable → decreasing the attenuation to crosstalk ratio → which impacts the Ethernet signal integrity when the electrical length of the cable exceeds 100 meters.

In addition, as more PDs are deployed, more cables in a bundle will be energized. More energized cables and elevated ambient temperature will cause the cable temperature to rise. Long-term elevated temperatures will degrade the performance of the cabling and may then cause permanent damage to the mechanical properties of the cable. Ultimately, this could lead to an exceedingly difficult and expensive remediation project.  

Moving toward URGENT?

Quadrant 1 of Covey’s book addresses issues that are both IMPORTANT and URGENT. This is where expensive change-outs, extensive troubleshooting, and a lot of frustration and pain occur. We are not quite there yet, but there is growing evidence this may be on the horizon.

Fortunately, there is a large body of knowledge that has documented DC resistance unbalance. The IEEE has published a standard with specifications that define compliance. Furthermore, there are handheld cable testers that can confirm compliance to these specifications during field acceptance testing.  Field acceptance testing is all fine and good, but after it has been completed there is no way to measure and monitor DC resistance unbalance while the network is active.

On the horizon are actions that could make code validation and certification imperatives for enterprise IT managers and owners. The 2017 NEC included new code to ensure that Class 2 and Class 3 data cables that support PoE applications do not exceed their temperature ratings. This has led to several states introducing new legislation that could alter the license requirements for installation, forcing the existing ecosystem of data cable installers and IT equipment integrators to hold a state-mandated electrical license in order to do their work. Will this really resolve the science and engineering problem? While legislation and additional licensing may or may not move forward, will it address the potential of data cable overheating? 

No. But that would absolutely move this topic from Quadrant 2 – Prevention to Quadrant 1 – Remediation. We have a better idea.

A Reasonable PoE Solution

PoE is NOT like a traditional electrical circuit. In PoE, the power source supplies power only after a valid connection is made with the PD. Continuous measurement of the current and the concept of a PoE circuit breaker would accomplish three things.

1. Provide continuous monitoring to assure compliance with the NEC ampacity table.
   
2. Become a practical way for enterprise IT and building owners to provide meaningful data to AHJs regarding compliance.
   
3. Allow end users to avoid higher cost by allowing them to maintain their current pool of contract installation services.

At NFLEXON, we are committed to finding useful solutions that can help our industry get in front of these challenges now, well before they become urgent and impact our industry. 

To learn more about our innovative, practical and compelling technology, we welcome you to visit us at www.NFLEXON.com and contact us about our future series of technology demonstrations that we will be hosting over the next several weeks. To learn more call 855-NFLEXON (855-635-3966) or email us at info@nflexon.com.