US code would require this to be a 4 wire setup. Since a Neutral and a Ground are required. It will work just fine the way LB describes but insurance would say 4 Wire. I learned this the hard way when running Italian Espresso Machines on my coffee carts and needed inspection. You can make the Yellow Green the Neutral and added a solid green ground or replace the entire wire from inside the machine with 4 wire cable. Both the Ground and the Neutral are grounded to the chassis of the machine so there is 0 function to the 4th wire but it is code.
