Power over Ethernet for IP Surveillance Systems

You've probably seen advertisements for POE switches and POE-compatible IP cameras. Here's what this all means, at least as far as IP cameras and other devices that are installed over an Ethernet network.

POE is an established technology that provides low-voltage direct current (DC) power delivery to network devices over the same wires that currently carry data. This means you can now run only one cable and still be able to both power the device and transfer data. The specifications come from the IEEE standard 802.af. This allows the powering device to use a voltage from 36-57 VCD. The most common voltage found is 48 volts.

Here are the different classes of POE devices.
Class Usage Maximum Power Levels at Input of Powered Device [Watt]
0 Default 0.44 - 12.94
1 Optional 0.44 - 3.84
2 Optional 3.84 - 6.49
3 Optional 6.49 - 12.95
4 Reserved (PSEs classify as Class 0)

One of the problems with CCTV IP cameras is that sometimes a heater, blower and a PTZ device are needed in some applications. The current standard only provides a maximum of 15.4 watts. Most PTZ devices and heaters and blower exceed this maximum.

There is good news on the horizon. A future standard, commonly referred to as POE+, is being developed by the IEEE 802.3at task force. There is still debate on the maximum wattage, but it is typically between 24 and 30 watts. This will allow many manufacturers to design their PTZ cameras with heaters and blowers around this new standard and still only run one cable to the camera location from the network switch.