I have a Kelvinator dryer with a four prong power cord. I need to install a three prong (220v) power cord. I have the second cord already in my possession. However upon inspection of the dryer, the four prong power cord obviously has four wires; red, green, white, and black. The three prong power cord has three gray wires. Which ones to I connect where? I believe the green one is the ground due to the fact that the connector is has a second wire coming off of it and going into the dryer. Is thissomething fairly simple that I can do myself or do I need a qualified electrician??