Power over Ethernet (PoE) technology has been using Cat 5e/Cat 6 Ethernet cables to transport electric power over a single data connection for years. This technology allows for a safe and responsive installation that does a great job collecting data as well as transmitting power, all at a reasonable cost.
PoE helps power such nodes and devices as VoIP phones, wireless access points, LED lighting systems, surveillance products, industrial controls, and network switches, using just one Ethernet cable. In fact, PoE powers at least a third of Internet of Things (IOT) devices, which today number in the billions. Smart homes, IP security systems, digital signs, and accuracy monitoring sensors in industrial settings all benefit from PoE technology. One of the main benefits of PoE is the labor cost savings experienced by not having to run separate electrical lines and outlets everywhere a device needs to be powered. And many people or businesses use PoE when they need to connect to an outdoor power source since it’s safer than standard electrical cabling.
PoE does have some limitations, however. These primarily relate to transmission distance, device compatibility workarounds, and power delivery rates. PoE’s transmission distance is limited to 100 meters (about 328 feet), which often proves ineffective for the needs of many potential users. The problem with short transmission distances doesn’t arise with the powered cable itself. An Ethernet cable can transmit power much further than 100 meters. A typical 23 or 24 AWG copper cable is actually limited by the test equipment used. Testers are designed to test only up to 328 feet (100 meters) and not exceed that limit. They will indicate a failure if the transmission distance exceeds that length, even if the signal continues to transmit beyond this limit. Therefore, a limiting factor in short transmission distances is also the test equipment itself.
So distance limitations come from the Ethernet cabling standards and the test equipment itself, as well as poor quality cable. These limitations require users to be creative and find new powered cable solutions for extended distance cabling.
How Far Can a PoE Cable Run?
A single PoE cable is limited to 100 meters, but PoE itself can power any device at any distance, provided enough power is generated at the source to operate the unit on the other end of the cable run. The true distance a PoE cable can run depends on the voltage required to operate the device to be powered and the quality of the cable itself. Most users rely on a Cat 6 cable for longer runs and a Cat 5 for shorter ones. The power supply for a short run typically needs to be 24V, while a long run usually needs 48V. Otherwise, the cable will not carry enough power to operate the desired device.
Do You Need Special Cables for PoE?
Regular and PoE-enabled local area networks both use the same kinds of cables, so special cables are not required when using PoE technology. Usually, a Cat 5e or better standard cable that includes four twisted pairs of copper cable will work. For comparison, electricity only needs two pairs of cable—a negative pair and a positive pair.
PoE cables also need temperature ratings higher than 60 degrees Celsius. Acceptable cables come in 60-, 75-, or 90-degree ratings, with the ratings referring to the temperatures the insulation can withstand. A higher rated cable can power a larger device, as it can effectively withstand the heat generated by the additional power transmission. Acceptable cables may also use different conductor sizes. As with the heat ratings, the bigger the conductor, the more power the cable can relay.
What Wires Carry Power over PoE?
The magic of PoE is basically this—the wires within the cable can carry data and power simultaneously without you as the user needing to modify the existing Cat 5 Ethernet infrastructure. With 10Base-T and 100Base-TX cables, two of the four wires get used. This means power moves along the same wires as data, similar to the phantom power technique in which a common voltage gets applied to each pair. In 1000Base-TX cabling, sometimes referred to as gigabyte Ethernet, all four wires transport data.
What Is a PoE Extender?
If you need to run Ethernet LAN signals farther than 328 feet, one option is to use a PoE extender. These were developed in 2005 in order to extend long distance power to devices such as PoE Wi-Fi access points and PoE IP cameras. Consumers liked these extenders because they helped lower the cost of installing PoE Ethernet devices. PoE extender solutions usually stretch up to about 4,100 feet from your source, or more than 12 times as far as a single cable alone. Fortunately, PoE extenders are not difficult to use. In general, it’s just plug-and-go technology. The extenders usually work so seamlessly that the user may never know it’s there.
Problems with PoE Extenders
While PoE extenders seem to be a great solution, one significant issue related to their use is the addition of another termination point (connector) to the channel. This can create one too many points in the channel, resulting in excessive noise and insertion loss, which will degrade the signal and render the cable inoperable.
BICSI installation standards are defined by TIA/EIA-568-C which defines a limit on the number of connectors used in the channel between the MDU (rack) and the connected device.
What About Powered Cabling Solutions?
A newer, more exciting trend to extend distances beyond PoE’s 100-meter limit is to use powered cabling solutions instead of an extender. That’s why we’ve introduced Activate™ Powered Cable Solutions at Remee Wire & Cable. Remee’s powered cable solutions help you extend power across extended distances. Our hybrid copper and fiber optic cable configurations can work with Ethernet networks in a variety of settings where an extender might not be a practical solution. For example, our cables can work in large-scale settings, including large buildings, government facilities, transportation facilities, and college campuses. In these environments, a daisy chain of Ethernet connectors would quickly reduce its own power supply to insufficient levels for powering a device.
Remee’s cable solutions include Cat 5e cables that carry 15.4 WPS, Cat 6 and Cat 6A cables that carry 30 WPS, and Cat 6 Limited Power for PoE++ that carry either 60 WPS or 100 WPS. The cables come with or without shielding and PVC jackets for protection. The top cables, which can carry up to 100W of power, also offer water blocking, direct burial and messenger versions.
Remee is using composite cable and Siamese cable to extend distances for hybrid data and power runs. As its name suggests, composite cable contains a combination copper and fiber hybrid solution that uses 12 AWG to 18 AWG conductors to carry additional power while the fiber optic strands carry more data. Composite cables can be built for rugged outdoor use as well.
Siamese cable constructions use two 18 AWG stranded bare copper conductors insulated with REMGuard™ Plenum Polymer, along with a fiber optic cable, to carry power and data beyond the 100-meter limit.
Where Can Network Planners Learn More about PoE Extensions Using Other Powered Cabling Solutions?
Remee offers Activate™ Powered Cable Solutions, which includes our PoE cables plus a series of hybrid composite and Siamese cables (fiber and copper) for extended distances. You can learn more about what PoE capabilities you may need for your specific application by using Remee’s distance/bandwidth chart. This chart allows you to visualize the power distance, data distance, and receiving end information of optimized cables for each level of power you may require. To learn more about PoE or Powered Cable Solutions in general and its advantages, benefits, limitations, and standards, check out Versatek’s article, What is PoE?
