Hey guys! I know this thread is a few months old now, but I finally found a PoE adapter that works with the C8! It's a Waveshare brand one, and I made sure to use a shielded cable that was then grounded at the patch panel and again grounded at the switch. I tested this with a multi-meter to be sure that it was grounded. The Waveshare PoE splitter has a separate connector coming from a separate section of the board that the Ethernet wires come off of from where the power components are. It also uses a little better quality capacitors than the UCTronics one. Not only that, but the whole thing has an extruded aluminum casing. I could ramble for hours, but anyway, here's the link to the PoE splitter that worked for me...
Side note, I also opened it up and put some aluminum tape around the Ethernet wires. I'm not sure if that really did anything, but it works!
And @rlithgow1 , I also use a pair of Cisco 3750X switches. 
