PoE Plus: What Is It? Tips And Considerations For Installing Your PoE Plus Solution
PoE, PoE Plus—what’s the difference? We run down the two Power Over Ethernet standards and some considerations you need to keep in mind when implementing a PoE Plus solution.
First Off, PoE
The great benefit of PoE or Power Over Ethernet is one network cable does it all — data and power. This not only eliminates the need to run two separate cables, but it means you can place powered IP devices like surveillance cameras in locations where a power outlet isn’t readily accessible. Power Over Ethernet or standard IEEE 802.af will support data transfer speeds of 10, 100 and 1000 Mbps and most importantly, provides 12.95W of power to your Powered Devices (PD).
PoE Plussed: More Power To You
Hey, why stop at 12.95W? Can’t we up the juice in the line to run more power hungry IP devices? Turns out, you can. IEEE 802.3at a.k.a. PoE Plus or PoE High Power was introduced in 2009 and established protocols to offer up to 25.5W to a powered device over network cable with data transfer speeds of 10/100/1000 Mbps. Now we can install outdoor IP cameras with external heaters for operation in extreme temperatures or add in surveillance cams with Pan/Zoom/Tilt features. PoE Plus will run Video IP phones, LED display boards, WiMax devices and terminal computers. And PoE Plus is backwards compatible with classic PoE for all your legacy gear.
This chart below, courtesy of TechAbstract, outlines the differences between standard PoE and PoE Plus:
PoE Plus is not only more powerful—it’s also more efficient, adding support for something called Link Layer Discovery Protocol (LLDP). LLDP lets the power source equipment, such as a 4-port PoE Plus switch, talk to the power device on the other end, requesting status information and dynamically allocating power when needed. This means your devices use their power more efficiently and only receive full load power when needed. Ultimately, you’ll be saving on your hydro bill.
Can You Stand The Heat?
Consequently, that stronger power current means there’s a good amount of heat emanating from the network cable. Heat dissipation is an issue to consider when choosing the right cable type for a PoE Plus solution. If you’re running bundles of cable, recognize that those cables packed in the middle of that bundle will get warmer due their inability to dissipate their heat. As heat builds up, so do the chances of signal loss occurring which can reduce the maximum allowed cable length. Not getting a signal to your device? The extra heat from PoE Plus may very well be limiting the distance data can travel. There’s also a chance that over time, the heat generated by the extra power in the line will damage or degrade your network lines.
The good news is that different categories of network cables perform differently when dissipating heat. Category 5e cable is poor. Cat 6 cable variations are better while Cat7 foil shielded twisted pair takes the less heat title belt.
This chart from the folks at Siemon.com shows the heat dissipation levels of the various cable standards used:
For any PoE Plus solution, choose your cable spec wisely based on the job you need to do, how long your cable runs will be and how much bundling will be involved. And of course, always use quality network cable to limit cable degradation and potential signal loss.