Power over Ethernet (PoE)

Power over Ethernet (PoE)

IEEE 802.3 - Power over Ethernet

Power over Ethernet, abbreviated as PoE, is a technology that allows power to be transmitted to devices over twisted pair cables in an Ethernet network. With this technology, we can supply power to devices such as VoIP phones, wireless access points, network cameras, switches, and computers, among others, where it is inconvenient to set up a separate power line. This technology is often compared to traditional telephone networks (POTS) that also receive power and data over the same cable (though analog data).

There are many different terms that refer to this functionality. Power over Ethernet (PoE), Power over LAN (PoL), Power on LAN (PoL), and Inline Power all refer to the technology of supplying power to various devices via Ethernet ports.

PoE can be implemented in many ways, including ad-hoc methods, but it is recommended to use IEEE standards for implementing power delivery over network cables.

The IEEE 802.3-2005 standard (commonly referred to as IEEE 802.3af) provides 48 volts, a maximum current of 400 milliamps, and a maximum power of 15.4 watts of DC over two pairs of twisted pairs in Cat. 5 cabling. After accounting for transmission losses, only about 12.95 watts are available for use, and most switched power supplies waste 10-20% of the available power.

Power over Ethernet (also known as PoE) is a technology that integrates power into standard network (LAN) infrastructure. Using the same cabling as the network connection (such as Cat. 5), PoE technology can provide power to IP network phones or network cameras and other network devices.

Power over Ethernet is particularly suitable for IP surveillance and remote monitoring applications because it eliminates the need to install power outlets at the camera end. PoE is primarily used in places where installing power outlets or cabling is too costly. Since PoE does not require independent power, additional cabling, and extra AC power outlets, it is more convenient and cost-effective to install. Furthermore, it eliminates the need to hire professional electricians for installation.

Another advantage of using Power over Ethernet is the functionality of an uninterruptible power supply (UPS). Many companies' PoE switches can connect to a UPS, ensuring that cameras and encoders can continue to operate normally even in the event of a power outage.

PoE technology adheres to all specifications of the IEEE 802.3af standard, designed to neither degrade the communication performance of network data nor reduce the transmission distance of the network. Power is delivered through LAN infrastructure, and power is automatically enabled when compatible devices are detected. Incompatible devices do not receive power. This feature allows users to seamlessly integrate traditional devices with PoE-compatible devices.

The standard can provide up to 15.4 W of power at the network switch or hub, with a maximum power consumption of 12.95 W at the device/camera end—making it suitable for indoor network cameras. However, PTZ (pan-tilt-zoom) cameras generally exceed this standard value, making PoE less applicable. Some brands also offer non-standard proprietary products, but it is worth noting that due to being non-standard, they cannot be mixed with devices from different brands. The 802.3af standard supports power classification, meaning that smart switches can conserve sufficient but not excessive power for device (camera) use—enabling switches to support more PoE device outputs.

We provide two options for our network video products: one is built-in support for Power over Ethernet, while the other lacks built-in support but can use a PoE Active splitter (which separates Ethernet and power for network video products that do not have built-in PoE functionality).

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