I am fixing up an old incubator. The power cord was cut off when I got it. It is a two wire cord. The tan wire goes to a junction block inside the fuse box, and the black wire goes to the fuse. I want to replace this cord with a new one, but all the cords at the hardware store with heavy duty wires were grounded, three wire. What should I do with the third wire? In this picture the power cord is coming in the left side of the box.