I use a 3 prong grounded for my input cords but there is no place to connect a grounded connection so it is probably a waste. I doubt that you will find many, if any, lights that are anything other than 2 wire spt so I use the cheapest 6ft extension cords I can find and just cut off the plug, tin the ends, and connect them to the board. I have seen folks use spt for the input cords as well if you are not pulling much of a load and they have never had a problem. YMMV, just my 2 cents.