Power-over-Ethernet: What Does the Updated 802.3at PoE+ Standard Mean to You?
Power-over-Ethernet (PoE) is a system that passes electrical power along with data over standard Ethernet cable—thus allowing a single cable to provide both data connectivity and electrical power to devices such as wireless access points or IP cameras. This gives installers the ability to run a single Ethernet line to a PoE-capable device, without the need for a licensed electrician or having 110 Volt AC at the point of installation. While PoE technology is not new, advancements continue to be made that allow for greater flexibility and expanded device support. PoE+ (also known as 802.3at) is the latest IEEE standard that makes it possible for more devices to be supported by PoE than ever before.
A Brief History of PoE
“Legacy PoE” was the first common version of Power-over-Ethernet and was never a ratified IEEE standard. It provides constant power over the Ethernet line, which can present a bit of a hazard when plugged into devices not designed for PoE. For this reason, the original IEEE 802.3af PoE standard was developed with the ability to contact the powered device to determine what type of power was needed and how much, thus protecting any non-PoE device from damage. More recently, the 802.3at PoE+ specification was introduced as a way to increase the amount of power available to devices.
What is the Difference Between 802.3af PoE and 802.3at PoE+?
The IEEE 802.3at (PoE+) specification is basically an extension to the original IEEE 802.3af PoE standard. It has one basic purpose—to provide more power to PoE powered devices. The original 802.3af PoE standard provides up to 15.4W of power (48 Volts DC at 0.32 Amps) to each device. With PoE+ (802.3at), the maximum output power jumps to 25.5 Watts (48 Volts DC at 0.52 Amps) sustained power and 30 Watts (48Volts DC at 0.63 Amps) peak power.
All other 802.3af features are carried over to the new 802.3at standard. This means existing Ethernet wiring can be used, 802.3af devices are still supported, and a licensed electrician is still not needed. It also means that many high-power devices that previously required a proprietary PoE injector or direct 110 Volt AC power can now be powered using a switch such as those shown in the first photo on this page. >>> NO ADDITIONAL CAPTION>>>>>