One common dilemma structured cabling planners face is determining the number and placement of electrical outlets among all the other wired connections in a cabling infrastructure plan. After all, every electronic device has to have a power source in addition to a data connection!
While it would be great to narrow everything down to one single cable carrying data and power to every device, we’re not there yet. There is still a need for a parallel wiring plan to carry voltage throughout the building in the traditional plug-in receptacle model. That may be changing in the future, though.
In the last 30 years, the sheer number of electricity-hungry machines in workspaces have multiplied, but an increasing number of them have miniaturized to the degree that they don’t need as much power as they used to. Cameras, climate sensors, controllers, VOiP phones, network access points, secure access controls, antennas and more don’t require the same amount of voltage as an old-school desktop tower computer and monitor. Laptop computers and handheld devices sip less power than lightbulbs.
Physical plants are becoming smarter and utilities like lighting and heating are more efficient. In order to maximize the potential savings, they require connections to controllers, sensors and programmed computing to effectively reduce consumption.
This is where PoE, or Power over Ethernet has a contribution to make. PoE is an ingenious solution that uses communication cables to supply low voltage power in addition to the data link. PoE standards were ratified in 2003 and 2009 making it possible to manufacture standardized equipment to meet demand. IEEE 802.3af sets forth the details of technology that can theoretically provide over 15W DC to a connected device. The actual deliverable current is closer to 13W.
When VOiP phones started to catch on, Power over Ethernet answered the problem created when the new phone bases needed a wall plug to work. Traditional phones were powered by the same copper wire that carried voice data to and from the dedicated telecom network, so it seemed like a step backward for the end user, not to mention that if the building’s power was interrupted, all the phones were dead as well.
Cisco was the first company to produce equipment that more closely followed the model of the old telephones by introducing a proprietary cable that enabled Ethernet cables to carry DC power to their phone stations.
Other companies soon followed suit and by 2002, it was a widespread solution.
Using a standard RJ45 terminal and CAT 5 cabling in a LAN setup, power may be transmitted on an idle twisted pair, since only two out of the four pairs is actually needed for data transmission in a normal 10-100 Mbps arrangement. Current can also be supplied on the data-carrying wires without signal loss.
Power supplies can be moved to communications closets, reducing the need for wall receptacles, power bricks, or batteries. Fewer wires cleans things up and allows for centralized management of dispersed devices.
While Power over Ethernet can’t yet completely replace the wall receptacle, there are many forces moving us toward fewer wires in the workplace. The trend toward cutting energy costs and minimizing the heating effects of high-voltage machines continues. We’re still a long way off from the paperless office, but it’s entirely possible now to reduce the number of copiers and printers in an office facility, eliminating a significant source of heat and power consumption.
Remote sensing and dynamic, responsive power distribution is now capable of routing power where it’s most needed and away from where it’s not. Turning off the lights or computers in an unused room may now be the job of the communications closet! As machines and power supplies evolve together, we’re going to see even more interest in eliminating high voltage power cables to save space, increase safety and reduce visual clutter.
For more information on this and other conundrums, see our offer “How Many Cables Should I Install to a Desk?” or click on us. We’re NetQ Media, an experienced multi-capacity company specializing in structured cabling for any size private or public projects.