How Many Devices Can I Connect to My PoE Ethernet Switches?

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by http://www.fiber-mart.com

Power consumption of 150W and 400W are the most popular choices on the market. The following are two switches from fiber-mart.com, 8 port PoE switch and 24 port PoE switch, and we’ll use them to further explain the question how many devices can we connect to my PoE Ethernet switches.
How Many Devices Can the 8 Port PoE Switch Connect?
fiber-mart S1150-8T2F switch is a managed PoE+ switch. It has 8 10/100/1000Base-T RJ45 ports, and 2 Gigabit SFP slots. Its PoE standard complies with IEEE802.3af/at. And designed with a max power consumption of 150W, each port can support up to 30W power. This means the switch provides the availability of PoE on all 8 RJ45 ports, and each port can potentially power devices that are connected. From the above, we know the standard PoE can supply 15.4W power for each port, and 30W for PoE+. Therefore, this switch can simultaneously connect 8(15.4W×8=123.2W<150W) devices that use IEEE 802.3af standard, and only 5(30W×5=150W) devices that use IEEE 802.3at standard. For example, if a typical outdoor IP camera needs a PoE power of 20W, the connection of 7 typical IP cameras will require 140W of PoE power (7×20W), which is well within the power consumption of this network switch.
How Many Devices Can the 24 Port PoE Switch Connect?
fiber-mart S1400-24T4F managed PoE+ switch is designed with 24 Gigabit PoE+ ports, 1 console port and 4 Gigabit SFP ports. This switch complies with IEEE 802.3af/at with a max power consumption of 400W and 30W for each port. Through a calculation, we know the 24 port switch can connect 24(15.4W×24=369.6W<400W) devices with PoE standard at the same time, and support 13(30W×13=390W<400W) devices with PoE+ standard. And as for the same outdoor IP camera with a power requirement of 20W, the 24 port switch can support 20(20×20W=400W) cameras.
Conclusion
Knowing the power consumption of PoE Ethernet switches is very important. If you want to connect multiple devices to a PoE switch, you need to calculate the total power consumption that all the devices require, and make sure you PoE switch can provide the needed current.

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