Power-over-Ethernet (PoE) supported devices are becoming more common in nearly every facet of home and business networking.
Martin Boulter & Brannon Young | Luxul
What is PoE?
- Legacy PoE—provides a full 48 VDC and 48 Watts at all times
- 802.3af—provides 48 VDC with a maximum of 15.4 Watts
- 802.3at (also known as PoE+ or PoE plus)—provides 48 VDC with a maximum of 25.5 Watts and is backwards compatible with 802.3af devices.
Why Use PoE?
- Cost savings – Only one Ethernet cable is required for both power and data. There is no need for expensive AC lines or additional breakers.
- No electrician needed – PoE is considered low voltage DC power, which does not require a licensed electrician to install.
- Flexibile installation – Devices can be located up to 100 meters (328 feet) away from the PoE source, making it easy to place devices literally anywhere, including outdoors using outdoor certified Ethernet cable.
- Easy device reset – Devices installed in hard to reach areas can be easily rebooted
Where would I use POE?
- In existing homes where running new wiring can be a challenge
- Remote outdoor locations (i.e. connecting an entry gate or remote IP camera)
- Wherever AC power is not readily available
- In cases where devices that are not easily accessible may need to occasionally be rebooted or powered off
How do I pick the right PoE source device for my installation?
- Switches: PoE Switches come in a variety of different options, so you need to be aware of what you are buying. For example, a switch may be advertised as a 24-port PoE switch, when in fact, only 8 of the ports are PoE, while the other 16 ports are Ethernet only. Others may only allow for some of the ports to be connected at full 802.3af or 802.3at output levels. Some switches are managed (allowing you to remotely turn power to PoE client devices on or off), while others are unmanaged. There are also performance differences between switches, with some supporting 10/100 Ethernet speeds and others running at full Gigabit speeds.
- Midspans: A PoE Midspan is a passive multi-port power injector that sits inline between a regular Ethernet switch and the powered device, injecting power without affecting the data. Midspans are used when there is no desire to replace and configure a new Ethernet switch, and only power needs to be added to the network.
- Injectors: A PoE Injector is basically a single output Midspan.
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