Rashmi Bhardwaj | Blog


Power over Ethernet, also known as POE, is a kind of technology that allows network cables to also carry electricity in order to power devices.The original IEEE 802.3af PoE standard provides up to 15.4 W of DC power (minimum 44 V DC and 350 mA) on each port. Only 12.95 W is assured to be available at the powered device as some power dissipates in the cable.


Following are the terminologies used in the PoE network –

  • PD – Powered Devices – PDs are end devices that can accept the power transmitted over Ethernet Cat-5 cable.
  • PSE – Power Source Equipment – PSEs add power to the ethernet cable.
  • Midspan device – These are power injectors that stands between the standard ethernet switch and the end device.
  • Endspan devices (PoE Switches) – These are Ethernet Switches that includes the circuit to inject power to the ethernet cable.


  • OPEX and CAPEX savings – by reducing the time and expense of having electrical power cabling installed. Network cables do not require a qualified electrician to fit them, and can be located anywhere.
  • Flexibility – without being tethered to an electrical outlet, devices such as IP cameras and wireless access points can be located wherever they are needed most, and repositioned easily if required.
  • Safety – POE delivery is intelligent, and designed to protect network equipment from overload, underpowering, or incorrect installation.
  • Reliability – POE power comes from a central and universally compatible source, rather than a collection of distributed wall adapters. It can be backed-up by an uninterruptible power supply, or controlled to easily disable or reset devices.
  • Scalability – having power available on the network means that installation and distribution of network connections is simple and effective.
  • Portability – Install end-devices where it is hard to get power. For example, you can install a wireless access point in the ceiling, where you cannot find power outlet.
  • Easy Maintenance – You can restart the end-device remotely. No need to press the power button to reset the equipment. You can easily move the end-devices wherever you can lay a LAN cable.
  • Simplicity – You need to run only ethernet cable to the end devices, which eliminates the cable clutter.
  • Safer – No AC power is involved, as you don’t need to install A/C power outlet for the end-devices.


  • VoIP phones
  • IP cameras including pan–tilt–zoom cameras
  • Wireless access points
  • IPTV decoders
  • Network routers
  • A mini network switch installed in distant rooms, to support a small cluster of ports from one uplink cable. (Mini-switches do not usually provide PoE on their output ports.) (Many modern VoIP phones include a two-port mini-switch that can provide a network connection for a nearby computer.)
  • Network Intercom / Paging / Public address systems and hallway speaker amplifiers
  • Wall clocks in rooms and hallways, with time set using Network Time Protocol
  • Outdoor roof mounted radios with integrated antennas, 802.11 or 802.16 based wireless CPEs (customer premises equipment) used by wireless ISPs.
  • Industrial devices (sensors, controllers, meters etc.)
  • Access control and Help-points (intercoms, entry cards, keyless entry, etc.)
  • Lighting controllers and LED Lighting fixtures[14]
  • Stage and Theatrical devices, such as networked audio breakout and routing boxes
  • Remote Point of Sale (POS) kiosks
  • Physical Security devices and controllers
  • Inline Ethernet extenders


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