When engineers combine power and communications using Cat 3 or Cat 5 cables, they can create inexpensive, efficient Ethernet networks. The Institute of Electrical and Electronics Engineers (IEEE) made the Power over Ethernet (PoE) standard because of its many advantages. Learn where it came from, how it works, and the many benefits of PoE.
PoE is a recently developed technology that grew as a response to a problem. Traditional telephones used copper wires to relay voice phone calls. As voice over internet protocol (VoIP) phones rose in popularity, users plugged them into Ethernet cables to send the signal. Since Ethernet cables didn’t transmit power, VoIP phones also had to be connected to electricity. If the building lost power, the phones didn’t work and the extra necessary connections often created a problem.
Cisco provided the first equipment in 2000 transmitting a 48V current through Ethernet cables to power VoIP phones. Other manufacturers quickly adopted the technique. It was so effective, IEEE soon required manufacturers to make all products PoE ready.
Since then IEEE has refined the standard to provide increased electrical power, make them compatible with 802.3af devices, and allow devices to communicate for improved energy efficiency.
How Does It Work?
PoE minimizes the number of wires necessary to distribute electrical current. Cat 5e and Cat 6 cables are made up of eight wires twisted together in pairs. In most situations, two of the pairs transmit information. The other two are called spare pairs, except in Gigabit Ethernet, which uses all four pairs.
The electrical current enters the data cable from the power supply through an injector between 44 and 57 volts DC. Power transfers through the cable to the PoE-compatible device. The cable protects users, but if the device is not compatible, it requires modification.
Benefits of PoE
PoE is simple to add to your network, either by utilizing a PoE switch with built-in PoE injection or by adding a midspan to provide PoE capability to non-PoE networks. Here are some of the advantages of installation:
- It saves time and money. Businesses avoid having to install separate electrical cabling. Installing network cables does not require an electrician, and they can be safely located anywhere without fire code concerns.
- It expands adjustability. Since devices don’t have to have electrical outlet access, they’re easy to move from place to place.
- It improves safety. Power surges through electrical outlets can damage equipment. PoE monitors power supplies to prevent equipment from damage. Owners can set many devices to conserve power for a better return on investment. Intelligent PoE minimizes waste and enables the power in unused devices to be rerouted to those that are in use.
- It increases reliability. Since PoE power doesn’t come from wall outlets, it isn’t interrupted if a breaker flips or anything in the system disrupts outlet supply.
- It provides scalable solutions. When power is available through networks, businesses make it available where it’s needed and can easily scale up or down with fluctuating needs.