Power over Ethernet (PoE) is a technology that allows network cables to carry electrical power. This system eliminates the need for a separate power supply, simplifying the process of installing networked devices such as IP cameras or wireless access points. PoE works by running power over the same cables used to transmit internet data. This is accomplished through the use of a PoE switch or injector, which adds power to the Ethernet cable at the source, and a PoE-capable device at the receiving end.
There are several standards for PoE, each dictating the maximum amount of power that can be transmitted. The most common standard is IEEE 802.3at, also known as PoE+, although older 802.3af802.3af: The 802.3af Power over Ethernet (PoE) standard, also known as Type 1, was ratified by the Institute of Electrical and Electronics Engineers (IEEE) in 2003. This standard allows for delivery of electrical power, along with data, to network devices over Ethernet cabling. Under the 802.3af… is still common, and 802.3bt is emerging for high power applications. PoE has many advantages, including cost savings, flexibility, and reliability. It can reduce installation costs by eliminating the need for electrical wiring and power outlets near each device. It also allows devices to be placed in locations where power is not readily available, such as ceilings or outdoor locations. Because PoE networks use a single cable for both power and data, they can be easily protected from power interruptions by installing a UPS-style battery system at the server rack. The maximum cable distances supported by each PoE standard and cable type must be observed carefully.
PoE Types
| Standard | Description | Power Output | Device Power | Voltage Range |
|---|---|---|---|---|
802.3af |
The 802.3af Power over Ethernet (PoE) standard, also known as Type 1, was ratified by the Institute of Electrical and Electronics Engineers (IEEE) in 2003. This standard allows for delivery of electrical power, along with data, to network devices over Ethernet cabling. Under the 802.3af standard ... |
15.4 W | 12.95 W | 44 to 57 Vdc |
802.3at PoE+ |
The 802.3at PoE+ standard, also known as Power over Ethernet Plus, is an enhancement of the original Power over Ethernet (PoE) standard. This standard allows for delivery of electrical power to network devices over existing Ethernet cabling, eliminating the need for separate power sources. The 802 ... |
30 W | 25.5 W | 50 to 57 Vdc |
802.3bt Type 3 PoE++ |
The 802.3bt Type 3 PoE++ standard represents a significant enhancement in the Power over Ethernet (PoE) technology. This standard allows for the delivery of higher power over Ethernet cabling, supporting up to 60 Watts of power at the PSE and 51 Watts of power at the PD (after cable losses). This is ... |
60 W | 51 W | 50 to 57 Vdc |
802.3bt Type 4 PoE++ |
The 802.3bt Type 4 PoE++ standard, also known as Power over Ethernet Plus Plus, is a technology that allows electrical power and data to be transmitted simultaneously over a single Ethernet cable. This standard offers significant advantages, including increased power output up to 100 Watts (at the ... |
100 W | 71 W | 50 to 57 Vdc |
Passive PoE |
Passive Power over Ethernet (PoE) is a non-standardised technology utilised in networking to deliver both data and electrical power to devices using a single Ethernet cable. Passive PoE differs from active PoE in that it constantly sends power over the Ethernet cable regardless of the device's needs ... |
24 W | Non-Standard | 9 to 56 Vdc |
Cambium 30 Vdc |
Cambium 30 Vdc PoE, a vendor-specific PoE, refers to a unique Power over Ethernet (PoE) solution provided by Cambium Networks. This technology enables the transmission of electrical power and data to devices over Ethernet cabling, eliminating the need for separate power sources. The Cambium 30 Vdc ... |
15 W | Non-Standard | 29 to 31 Vdc |
Starlink PoE |
Starlink uses a non-standard Passive PoE protocol in order to output up to 150 W. Its pinout is 1236+ and 4578-. The UT requires 41.1 to 57.0 V. |
150 W | 96 W | 52 to 57 Vdc |