What is Power over Ethernet (PoE)? Everything You Need to Know!

What is Power over Ethernet (PoE)? Power over Ethernet (PoE) is a technology that enables the transmission of both electrical power and data over standard copper Ethernet cables. This innovation simplifies network setups by allowing power to be delivered through the same RJ45 Ethernet connector that carries data. PoE networks can supply power directly from a network switch or by using a PoE injector to add power to an existing data line.

How Does PoE Work?

PoE operates through power sourcing equipment (PSE) that sends direct current (DC) voltage over Ethernet cables to a connected device, referred to as a powered device (PD). This eliminates the need for local power sources near the devices, as the power is transmitted over the same cables used for data, reducing the complexity and cost of installations.

History of Power over Ethernet

Before PoE, devices like security cameras needed separate signal cables and power supplies, often leading to complicated installations. Power was typically delivered from a central location using dedicated power cables. The introduction of PoE revolutionized this process, as it combined data and power in a single cable, making installations more efficient. PoE became a standardized solution in 2003 when the Institute of Electrical and Electronics Engineers (IEEE) formalized it.

Power over Ethernet Standards

The IEEE has developed several standards for PoE over the years. The first, IEEE 802.3af, allowed PoE switches to deliver up to 15.4W of power. Over time, this evolved into more advanced standards, including PoE+ (802.3at) and the latest standard, 802.3bt, which supports up to 100W using all four pairs of Ethernet cables. This progression has allowed PoE to power increasingly demanding devices like wireless access points and security systems.

IEEE Standard Power Available Year of Standardization 802.3af15.4W2003802.3at30W2009802.3bt60W-100W2018

PoE Transmission Techniques

PoE operates using various methods to transmit power. Mode A sends power over the same pairs used for data transmission, while Mode B uses spare pairs of the Ethernet cable. In 4-pair PoE (4PPoE), power is sent over all four pairs for higher power delivery.

PoE Mode Ethernet Cable Pairs Used Pin Allocation Mode AData Pairs (Pins 1, 2, 3, 6)Pins 1, 2 = DC+, Pins 3, 6 = DC-Mode BSpare Pairs (Pins 4, 5, 7, 8)Pins 4, 5 = DC+, Pins 7, 8 = DC-4PPoEAll 4 Pairs All pins used for power delivery

Power over Ethernet Classes

Powered devices (PD) are categorized into different classes based on their power requirements. These classes range from 0 to 8, with higher classes supporting devices that need more power.

Class Wattage Required at PD00.44–12.94W10.44–3.84W23.84–6.49W36.49–12.95W412.95–25.50W5-840W-71W

Maximum Distance for Power Over Ethernet

Standard PoE has a reach of up to 328ft (100m), but new innovations in PoE technology have extended this distance significantly. PoE now supports transmission over various types of cables, allowing power and data to be delivered over greater distances for devices in remote locations.

Advantages of Power Over Ethernet

1. Lower Infrastructure Costs By using existing Ethernet cables for both power and data, PoE reduces the need for additional wiring and power sources. This results in significant cost savings in installation and infrastructure.

2. Fast and Simple Deployment PoE makes it easy to deploy devices without the need for complex electrical work. Devices can be connected directly to the network, making it quick to set up IP cameras, wireless access points, and other devices.

3. Improved LAN Design PoE provides flexibility in network design. Separate PoE networks can be maintained for specific applications like security or communication systems, or they can be integrated into a central network. This approach improves security, performance, and manageability.

4. Less E-Waste By reusing existing infrastructure and reducing the need for additional equipment, PoE contributes to a more environmentally friendly approach to network installations.

Testing PoE Made Easy!

The new PoE Pro eliminates guesswork and documents proper operation when installing, maintaining and troubleshooting network cabling.

Test results are stored in real-time on the free AnyWARE mobile app and are seamlessly uploaded to AnyWARE Cloud where professional PDF reports are generated.

Previously technicians had to understand all the various standards, device power outputs and cable lengths to be sure a device will operate successfully.

The PoE Pro identifies the Class of the PoE source and power available to a PoE device regardless of cable length, cable quality or other factors. Provides a clear pass/fail result to IEEE 802.3af/at/bt standards.

PoE Pro identifies network switch speeds of 100M/1G/2.5G/5G/10G to test switch configuration and ensure desired network speed at installed device locations. TDR technology enables fast and accurate location of opens and shorts anywhere in the cable.

With Power over Ethernet, you can streamline your network, reduce costs, and future-proof your infrastructure for continued growth, all while maintaining a sustainable approach to power and data transmission. Please feel free to reach out to any of the industry experts at Cable and Connections for more information.