Power Over Ethernet (PoE) Switches : Understanding the Magic Box

A Power over Ethernet (PoE) switch is a device that powers a remote Ethernet device by transferring electrical power over the same Ethernet cable that sends data transmission to & from the device.  This will help reduce cost of cabling as well as save time while installing, since you won’t need multiple cabling for each camera.  I’m going to break down how to figure out which PoE switch is the correct one for each specific security system.

How many power over Ethernet ports are on each switch?

Most of the time, it should list in the switch specifications how many ports are available for PoE.  Make sure you pay attention to this, otherwise you won’t be able to power your cameras through the standard ports.

How do I figure out how much power is transmitted through each port?

You need to pay attention to a couple things when looking at a PoE switch.  First, how much power does the entire switch offer? Second, how much power does it offer per port?  Most people think it’s as simple as taking the power of the entire switch and dividing by how many PoE ports are on it.  This is not the case, and is typically the #1 mistake made by installers. In most cases, you will get about 15w of power per port.

If it says it has 8 PoE ports, can I hook up 8 cameras through it?

8-Port PoE Midspan

Sometimes, but not always. You’ll need to read the specs of each camera that you’ll be powering through the switch to find out exactly how much power that camera requires. Then you’ll need to check the max power supplied through the entire switch.  After you’ve done this, you can figure out how many cameras you can connect to the switch. Oftentimes IP cameras are power-hungry, and if you don’t pay attention to these details, you will end up not having enough power for your cameras to operate properly.

Understanding PoE switches is essential for successfully installing IP cameras. By knowing these basic guidelines it should make your shopping for a PoE switch that suites your needs a little bit easier.  Just remember that using PoE switches will ultimately save money, time, and space when installing a camera system.