I’m using Ethernet extensively in my Arduino home automation system for communication with devices distributed around the house, so being able to also provide power to those devices over the same network cable is a big time saver. Until now I’ve been using a “DIY” approach to Power-over-Ethernet (PoE) with midspan injectors sending about 10-12V down the wire, but I’m now converting it all over to use Netgear switches with 802.3af (48V) PoE support built in.
This episode covers some of the options for PoE with Arduino, and demonstrates how you can do it both in a cheap DIY method and using commercial PoE switches.