Power Over Ethernet

 By Andrew Burger

A precursor and keystone on the path that’s led to all that is the Internet, Ethernet networking continues to advance and adapt to evolving technological environments and the needs and requirements of organizations and individuals. Today, that includes delivering electrical power, alongside digital data and communications, to an expanding range of devices and equipment…

Ethernet plug adapter

The first means of linking PCs to form local area networks (LANs) in offices and within and between buildings, use of Ethernet networking is now ubiquitous. Invented by Bob Metcalfe while working at Xerox PARC in 1973, today’s Ethernet technology can transport digital data at 100 gigabits per second (100 Gbps) across metropolitan areas and, via carrier Ethernet services, worldwide. Proponents are pushing the Ethernet envelope out further, or in the case of Power Over Ethernet (POE), inside organizations, buildings and homes. As a result, new Ethernet software, equipment and cabling is now being used to deliver low-voltage, DC power alongside digital network traffic to VoIP phone systems and camera networks, for instance.

Power Over Ethernet and LED Lighting

The big advantage to end users, and the attraction for vendors, is that POE makes use of existing in-building fiber, cable and DSL network infrastructure, thereby minimizing acquisition and installation costs, hastening deployment and raising productivity and returns on investment (ROI).

Aiming to expand use of POE geometrically, leading vendors have set their sights on convincing organizations to use POE to power lighting, more specifically LED lighting. The benefits would be substantial and wide ranging, proponents say, from lower energy bills, energy consumption and pollution to enhanced utility grid performance, reliability and resilience. In addition to improving the energy efficiency of already highly efficient LED lighting, making use of POE would ease the way to participate in utility demand response (DR) programs and, generally speaking, enhance energy use and management in buildings of all types, from “smart” homes, residential and commercial buildings to smart university and corporate campuses, they assert.

Home network installation


AC (alternating current) electricity has been the de facto industry standard in the U.S. and homes around the world since the late 19th century and the so-called “War of Currents” that pitted Nikolia Tesla and Westinghouse against Thomas Edison and the Edison Electric Co. Tesla and Westinghouse won the competition, but DC electricity continues to surround us, powering everything from consumer electronics and household appliances to industry equipment.

Edison VS Tesla

The main reason AC won out over DC was its ability to more effectively transmit AC electricity over long distances—from Westinghouse’s hydroelectric power plant at Niagara Falls, New York, to industrial consumers down state in the first instance. Hydroelectric generators produce DC electricity, as do other power generation technologies, including wind turbines and solar photovoltaic (PV) panels. The DC electricity produced is converted, or inverted in industry-speak, to AC and voltages ramped up and stabilized before it’s transmitted long distances along power lines, then stepped down to lower voltages for local distribution and consumption.

Energy is lost every time DC-AC conversions are made, however. Hence, there’s an inherent inefficiency built into power grids, and that means we wind up using more electricity than we otherwise would. In addition, many of the electronic products we use on a daily basis, computers and wireless/mobile networking and telecoms devices, for instance, run on DC power. As a result, we’re losing some small amount of electrical energy and power every time we use our computers and mobile phones. POE avoids that pitfall by delivering low voltage DC power to electrical and electronic devices. That eliminates all those DC-AC conversion losses, which add up to a lot of energy considering the number of devices in use today and how frequently they’re used and for how long.

Tipping the Economic Scales

The energy efficiency gains that can be realized via POE are substantial, but it’s the additional benefits that tip the scales definitively in POE’s favor. “POE technology wins when you add the advanced benefits of networking the lights using the Ethernet local area network (LAN) and the lower costs of LED maintenance,” say Maxim Integrated’s Alec Makdessian and Thong Hunyh.

Network system

While acknowledging POE’s benefits, there are a good number of key factors those looking to deploy POE need to be on the lookout for and be prepared to address, according to lighting industry specialist Lux:

  • “Ensure your Ethernet network is robust enough to ensure POE lighting software and devices are always recognized and persist over time according to building/facility, organizational and end user requirements. For instance, power outages may call for a a re-boot of POE lighting systems.”
  • “Fluctuations in electrical current can cause POE software glitches and system shutdowns. That raises the need for emergency back-up power so that repairs don’t have to be made in the dark, as well as POE system fail-safes so that lighting is restored automatically,” Lux notes.
  • POE lighting network traffic can interfere and degrade the performance of Ethernet data communications and overall network performance. Ensuring the load lighting falls within the bounds of network capacity and throughput is essential in order to avoid potentially catastrophic failures. In addition, it’s essential to make sure that lighting loads don’t exceed the capacity of Ethernet cabling to carry electrical current.
  • Don’t expect POE to eliminate the need for an qualified electrical contractor because it’s low voltage and “plug n’ play,” Lux cautions. “This argument forgets that every cable termination needs to be made into an Ethernet plug, and that’s more complex than a standard mains connection into a lighting fixture.”
  • Small, seemingly inconsequential, energy losses among wiring connections can accumulate and wind up creating a substantial loss across the system overall. The power rating of Ethernet cabling and terminal connections need to be checked and upgraded to ensure they match load requirements. In addition, Lux recommends using only the very best POE, Ethernet and electrical components and equipment possible.

Navigant Research foresees POE growing rapidly in coming years. In market research released in January 2016, Navigant forecasts POE lighting revenues will increase at a 32.2 percent compound annual growth rate (CAGR) and expand over 10-times from 2016-2025, rising from around $35.8 million to $419.9 million.

SEE MORE: Network computing: new energy challenges by Andrew Burger

about the author
Andrew Burger
Andrew Burger has been reporting on energy, technology, political economy, climate and the environment for a variety of online media properties for over five years.