Copper Is the New Black: Is Copper Making a Comeback?

Published On
Sep 12, 2018

I spend most of my time with fiber optics, but I have quite a bit of experience with copper cabling too. Fiber is always in the news, and wireless threatens to take over all communications; copper has been quiet and has not produced much excitement until recently. Now it has got me wondering if it’s going to make a comeback, but in new forms and applications. The three aspects of copper I want to discuss are power over ethernet (PoE) and lighting, wireless infrastructure, and single-pair ethernet.

Structured cabling took a big hit when Wi-Fi became fast enough to replace the Cat 5 desktop connection with a mobile link. When the Fiber Optics Association (FOA) says “Cat 5,” it refers to the entire unshielded twisted cable family—Cat 5/5e/6/6a—for simplicity. It certainly did not go away, but, in many enterprises, LANs exist mainly to support Wi-Fi access points and the few power users who want a hardline connection to their desktop computers.


Many of you are probably aware of the push to use PoE for lighting and other uses replacing alternating current (AC). Originally an ethernet standard for providing ~15 watts (W) to power Wi-Fi access points or voice over internet protocol (VoIP) phones, PoE grew to allow higher power, first ~25, then ~55 and now ~100W. The FOA uses the tilde symbol (~) to indicate approximate powers because using PoE requires reading the fine print, covering issues such as length, conductor size and how many pairs are used.

To confuse issues around PoE, the IEEE committee that was writing the standards did not trademark the name. So what is called a “PoE application” might have no connection to the actual IEEE standard. That concerns many suppliers because the cable has smaller conductors with higher resistance and for the same power delivery as regular AC power cables, resistive losses are high. Oh, one more thing: there are also dangers from counterfeit cables with copper-clad aluminum conductors, which have higher resistance overheating and arcing during connections, and that damages modular connectors.

All of those negatives don’t seem to bother people who hype PoE applications, but it has led to concerns among contractors. The FOA is creating a PoE training program as part of the its premises cabling certification curriculum to clear up the uncertainty.

Wireless infrastructure

There is another application for traditional structured cabling that has not been widely discussed. Everybody knows Wi-Fi depends on Cat 5 and PoE to connect and power wireless access points. In some premises networks, I have also seen cellular distributed antenna systems (DAS) that follow the architecture of structured cabling but connect on single-mode fiber. Sometimes, DAS will use the same cabling as a passive optical LAN based on fiber to the home technology.

Recently, I’ve seen a new type of product, a cellular antenna for indoor use that is based not on DAS technology but on the new generation of small cells used outdoors in urban environments. These small cells connect using ethernet over Cat 5 with PoE, not proprietary cellular protocols over single-mode fiber.

This is big. I’ve been told DAS has peaked because all of the sports stadiums and convention centers have been completed and DAS is too expensive for enterprise LANs. Now a company can add some Cat 5 drops and some of these new small cells and subscribe to a service that provides the connection to a cellular system. Wi-Fi and cellular would both be available in their offices, and structured cabling would be rescued yet again.

Single-pair ethernet

A few years ago, the IEEE ethernet committee created ethernet that operated over a single twisted-pair cable, rather than the traditional 4-pair Cat 5. More recent standards are looking at lengths up to 1 kilometer and including PoE. Single-pair ethernet was intended for industrial applications, but interest grew for automotive uses too. Word gets around, so dozens of other applications became interested, including video, building management, fire alarms, RS-232, RS-485, and that ever-popular catch-all, the internet of things.

Part of the interest comes from the fact that most of these applications do not require a 4-pair cable, so Cat 5 is overkill, more expensive and wasteful. A single-pair cable should be much smaller, lighter and cheaper. Expect the modular eight-pin connector—the one everybody erroneously calls an RJ-45—to be replaced with one or more connectors that are smaller with options for rugged environments.

Certainly, all of this shows that copper cable is not dying but changing along with the technology it connects.

About the Author

Jim Hayes

Fiber Optics Columnist and Contributing Editor

Jim Hayes is a VDV writer and trainer and the president of The Fiber Optic Association. Find him at

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