What is PoE?

What Power-Over Ethernet Can Do For Your Home

Topics in This Article: PoE Standards, Power Delivery and Necessary Connections for each PoE standard, Hardware Options

 

With the addition of PoE to our Deco Line of Products with the Deco X50-PoE and Deco X50-Outdoor, the team has prepared a few resources to help understand PoE and its benefits.

 

Power-Over-Ethernet, or PoE, allows compatible switches to transmit both power and data through an Ethernet cable simultaneously. PoE makes it easy to both extend your existing wireless network, and provide power to devices nowhere near an energy source.

 

Useful Acronyms to Know:

 

PoE: Power Over Ethernet –  Universal Standard allowing Power Delivery over Ethernet Wiring

PSE: Power Sourcing Equipment – Any Device that adds Power onto an Ethernet Line

PD: Powered Device – Any Device Powered via PoE

 

PoE Standards:

 

IEEE802.3af standard (2003)

• IEEE802.3af standard defines the maximum output power from a single port to be 15.4W, and it can supply power to devices under 12.95W (such as IP cameras) through an Ethernet cable.

 

IEEE802.3at standard (2009)

• IEEE802.3at standard is based on IEEE802.3af and can be regarded as the enhanced version of the IEEE802.3af. The power from a single port is up to 30W, and it can supply power to devices under 25W, which can meet the requirement of higher-power devices such as video Phones, PTZ devices and etc.

 

IEEE802.3bt standard (2018)

• 802.3bt is one of the newest standards and can provide up to 60W from a single port, and it can supply power to devices under 51W. It is usually used to power a device that requires high power.
• IEEE PoE standards have backward compatibility. The latest standard, IEEE 802.3bt, is fully backward compatible with the older IEEE 802.3af and IEEE 802.3at standards.

 

 

PoE Standards and Power Delivery

Common Name	Standard	Power to Device	Max Power Per Port	Ethernet Cable Needed
PoE	IEEE 802.3af-2003	12.95W	15.4W	CAT5E
PoE+	IEEE 802.3at-2009	25.5W	30W	CAT5E
PoE++	IEEE 802.3bt-2018 (Type 3)	51W	60W	CAT6A
PoE++/ Hi-PoE	IEEE 802.3bt-2018 (Type 4)	71.3W	100W	CAT6A

 

Active vs Passive PoE Energy Consumption and Behavior:

 

In terms of power consumption and delivery, there are actually two types of PoE, one following a universal standard and one that does not.

 

Active PoE is usually what is referenced with PoE. Active PoE connections work to negotiate with the Switch or Adapter to receive the correct amount of power, and the switch or adapter will stop sending power when the device is turned off or disconnected.

 

Passive PoE is a non-standardized form of PoE where a set amount of power is delivered without communication from the end device, effectively creating an 'Always On' connection. As the devices do not communicate with each other, there is a much higher chance that the receiving device could be burned as a result of the excess power. For this reason, it is recommended to use Active PoE connections for both safety and also to decrease energy usage.

 

 

How Does PoE Actually Work?

 

Any Ethernet Cable that meets a CAT'X' standard consists of 4 sets of twisted pairs (two small wires twisted together). Each Increasing standard, CAT5e/6, provides additional insulation for these ‘twisted pairs’ so that more data and power can pass through the cable without interfering with the other twisted pairs.

 

The original PoE Standards were very simple in their implementation of PoE, using a dedicated twisted pair of cables to transmit power through the cable and reserving the other twisted pairs for data transmission. In order to pass more power through the line, while allowing for faster connections the newer standards pass both data and power through all the twisted pairs simultaneously.

 

While this seems like it would be extremely complicated, it is actually a very simple implementation of the technology. The electricity and data are separated on the twisted pair by using completely different frequencies. The power for a home in the United States is traditionally operating at 60Hz or less. The frequencies passed through an Ethernet cable to pass data through an Ethernet cable can be Ethernet cable are much higher than that. This is why you will often see data transmission speeds listed as MHz, as the frequency is extremely high.

 

How to Add PoE Connections to your Network:

 

PoE Network Switches

PoE Network Switches come in a variety of sizes, but the most common PoE Switches for home use will either be a 4-port or an 8-port network switch. Switches provide an easy means of providing power to multiple devices on a network. Each network switch will have a specified pool of power that can be distributed across the PoE-enabled ports, so make sure that you are aware of the total power consumption of the devices before adding new PoE devices to the same switch. This is the most common setup for PoE Networks, as it requires the least overhead and has the most options for network customization.

 

PoE Injectors

A PoE Injector serves to add power to an existing Ethernet cable. Injectors normally consist of an Ethernet Input, and Ethernet Output, and a Power Source. Using these devices can allow you to skip the pains of adapting an entire network infrastructure or running new cables for one PoE device.

 

PoE Splitters

PoE Splitters are actually considered end devices for PoE lines, as they receive a PoE signal and separate the power from the line so that the signal can be compatible with non-PoE Devices. This is especially useful if you would like to place a non-PoE device at a location with no nearby outlets. These types of devices are often sold generically and are not guaranteed to work with any devices, this should be avoided unless necessary.

 

PoE Extenders

Power over Ethernet is normally limited to a maximum length of 100 meters. PoE Extenders serve to increase the strength of the signal being carried through the line by another 100 meters. Extenders come in multiple varieties such as being in-line without a power source, or with a power source. Some extenders are even rated to be placed underground or daisy-chained together allowing for the easy hiding of Ethernet cables over longer distances.

 

Learn more about PoE, compatible devices, and TP-Link's Switch and Adapter Offerings Here: What is a PoE Switch?