I have been diving in to POE for a few months now and I have learned quite a bit. You may want to visit http://find-a-poe.com/ , which is texas wifi company. Their website has some good info what you are trying to do. I am now using the information I have learned here to inject 12v, 24v and 48v over cat 5e. I am using using the Opensprinkler micro controllers along with ubbiquity radios and hikvision cameras, all being powered with poe. Anyhow good luck, and maybe this will help you out.