PoE Switches are used for providing PoE functionality when a router doesn't otherwise support the feature. If you aren't familiar with PoE, it refers to power-over-ethernet. Basically, it means that a compatible device can receive electrical power from a hardwired ethernet connection. This is in addition to the network connectivity. In other words, you won't need to provide a separate cord for providing power to the device. Both network connectivity and electrical power will come from the same connection. This can save you a lot of trouble when running wires. After all, setting up an entire network of wired ethernet cables can truly become a demanding task. But with PoE switches, you can make your life easier.
Before you go shopping for PoE switches, also known as PoE injectors, there are a few things you should keep in mind. For one some routers already offer PoE functionality. This means that you can connect a compatible device and expect it to receive electrical power from the ethernet connection, all without needing to use a PoE switch or a PoE injector. In these cases, you do not need to spend extra money on a PoE switch or PoE injector accessory. Check the specifications for your router to see if it supports power-over-ethernet using its standard hardware, as you might not even need a special add-on.
Additionally, you should make sure the device you are using supports power-over-ethernet technology. Some hardwired ethernet devices can only receiver power from a plug-in adapter and/or a battery. Even if you connect a wired ethernet connection with a router using a PoE switch, it will still be impossible to pwoer certain devices in this manner, simply because they lack PoE functionality. Again, check the specifications for the device you are using, and make sure that it is capable of supporting PoE before you try and go and achieve a potentially impossible setup.
Some of the most popular devices for use with PoE switches are IP cameras. Alarm.com even manufactures their own PoE injector, due to the fact that many of their security cameras support PoE technologhy. If you are setting up Alarm.com Cameras, and your router does not support PoE on its own, then you might consider getting a PoE switch for that application. Remember to check and make sure that your Alarm.com Camera supports PoE, as not all of their cameras can be used in that way. Also keep in mind that the PoE injector will still require its own power source somewhere. Usually, the PoE injector plugs into a wall outlet using a standard adapter. If you want to set up a backup power supply in the form of a backup battery, both the router and the PoE injector will need their own batteries.