Mine is the common 3-prong dryer plug that Hang Glider posted, except that center screw appears to be VERY recessed (so much so that I can't quite tell if it is a screw or not at the bottom of the hole).
I am a residential electricity neophyte, but I study electrical impulses in nerves for a living so I have a fair theoretical understanding of electricity--enough to know that I currently know just enough to kill myself, but not build a useful rig. So, I'm just trying to figure out what I have at my disposal so that I have a starting point for learning.
I'm currently just building my two cooler, one burner AG rig and any electrical components are quite a ways off. I would probably start with an electric HLT to keep the initial wattage requirements down. In the meantime, I just want to get a basis for learning.