Quoted from lhammer610:Cointaker says to run the single grey wire to the backbox and plug it into an empty 3 hole plug with grey and black wires.
It absolutely does not say to run it to the backbox*. Check again.
You need to run it to the back of the lower cabinet, where you'll find the plug you need.
Good luck.
*Though I read it the same way the first time I read it.