PoE++ vs PoE+ vs PoE Switch: How to Choose?

- PoE switch
- PoE+ switches
- PoE++ switches (Type III & Type IV)

All four types of PoE switches are capable of providing power and LAN connectivity. Wondering about the differences between them? Don't know which one to choose? This post is about the differences between PoE switches and when you should choose one. 

Was ist PoE (Power over Ethernet)?

Nowadays, PoE is quite well known. However, it is not a very new technology as it was introduced in 2003. IEEE 802.af is the standard that defines PoE. We can power devices such as VoIP phones and IP cameras via PoE and communicate with them over a single standard Ethernet cable. As we all know, standard Ethernet cables consist of four twisted pairs.
The basic PoE standard uses two twisted pairs for data transmission and the remaining two for power transmission. The latest version of the PoE standard allows data and power to be transmitted together over all four twisted pairs of the Ethernet cable. However, PoE technology has evolved over time and the IEEE has introduced additional standards to improve the power transmission capabilities of PoE connections. The following figure illustrates the basic difference between 2-pair and 4-pair PoE.

What is a PoE switch?

PoE switches are those that are designed to comply with the basic PoE standard. These switches act as PSE (Power Sourcing Equipment) to supply the PoE-compatible Ethernet devices in a LAN with the necessary power. A typical PoE switch can deliver a maximum power of 15.4 watts per port and operate in the voltage range of 44 to 57 VDC. These switches can supply devices with a nominal operating voltage between 37 VDC and 57 VDC. It is important to understand that only a PoE compliant load can be powered by a PoE switch via an Ethernet cable. The following illustration shows the main functions of each PoE switch, regardless of its type.

What is PoE+ and what are PoE+ switches?

After the introduction of PoE, manufacturers began to develop PoE-compatible devices, but the low energy budget of PoE technology became a problem. To solve this problem, the IEEE launched a new version of PoE (PoE+). PoE+ is an improved version of basic PoE, and a separate standard IEEE 802.3at (2009) defines PoE+.

The PoE+ switch generally supplies up to 25.5 watts of power to the connected powered device (PD). The maximum power in watts that each PoE+ connection can deliver is 30 W. PoE+ works with CAT5 Ethernet, as opposed to basic PoE, which can work with CAT3. However, both PoE and PoE+ use only two twisted pairs to transmit power over an Ethernet cable. The operating voltage range of the PoE+ switch ports is 50 VDC to 57 VDC.

What is PoE++, and what are PoE++ switches?

PoE+ was indeed better than basic PoE technology in terms of power budget, but the IEEE continued to work on developing a new PoE standard that could deliver more power. PoE+ works well for small devices like IP cameras and IP phones, but it can't provide enough power for more power-hungry devices like LCDs and laptops.
PoE++ was defined by the IEEE standard 802.3bt, which was introduced in 2018. It was developed to supply power to a wider range of devices. PoE++ can be divided into two types (PoE Type III and PoE Type IV). A PoE++ type III switch can supply up to 51 watts of power. In contrast, type IV PoE switches can supply up to 71 watts of power and use all four twisted pairs of the Ethernet cable. The maximum power per connection specified by IEEE 802.3bt for type III and IV PoE++ switches is 60 and 100 watts respectively. PoE++ switches require at least CAT5 cables for operation.

How do I choose between PoE switches?

Based on our discussion, we now know the differences between the four PoE versions. In the table below, you can find and compare the basic specifications of PoE, PoE+ and PoE++ (Type III and Type IV). This table can help you choose the right type of PoE hardware for your application requirements. 

The main difference between the various types of PoE switches is their power transmission capacity and their operating mode. Each PoE switch can fulfill the two main functions for which this technology was developed. 802.3af (Type 1) PoE switches are generally used for small devices that require
802.3at (Type II) PoE+ switches can deliver more power per connection. They are generally recommended for devices with medium power consumption, such as complex, motorized security cameras and larger wireless access points with multiple antennas. However, PoE+ switches are not powerful enough to power more demanding devices such as flat screens and laptops.

Type III PoE++ switches can support heavier loads such as building management devices and high wattage video conferencing systems. Type IV PoE++ switches are available for even heavier loads such as televisions and laptops. Type IV switches can deliver up to 71 watts of power, so these switches can power almost any PoE-compatible wired network device.

If your application only involves small loads and simple devices, you can make do with the simple PoE switches. However, if you want to build a more robust, expandable and scalable network, you need to consider PoE+ or PoE++ switches. If your current PoE infrastructure is working well and can adequately power the devices you already have installed, it may be better to leave it untouched. Similarly, those planning a network upgrade should make a wiser choice, as upgrading from a simple PoE infrastructure to a PoE++ infrastructure is unnecessary in all cases.

Conclusion

The increasing demand for power and the development of PoE-compatible devices with higher power consumption prompted the IEEE to invest heavily in the research and development of PoE. Today, there are three PoE standards and four PoE types to work with. Each PoE switch can provide you with the essential functions of connectivity and power transmission over Ethernet. However, when planning a network, you should choose a specific type to ensure an adequate power supply for the built-in PDs (Powered Devices). In this article we have discussed all PoE types and the main differences.