2 Wire 120v

Installing a new out let in the kitchen.The outside outlet has 3 wires going to it you can see under the kitchen counter.I found the one with the most slack but it looked if you cut it into the end would look like a figure 8 to thin in the middle to have a ground wire in it.Went ahead and used one of the other ones to tie into.Does anyone have idea what it is?Looks like it goes through the floor as near as I can see.