The dryer can be run on either 3-wire or 4-wire. Our previous dryer was a gas dryer so we needed to run a new line, and we ran a 4 wire. But the dryer can be hooked up to older 3 wire systems as well. Just make sure you purchase the correct cord for your home (the dryer doesn't come with a cord). You will need to switch a wire in the wiring panel when you hook up the cord. The instructions in the book are very clear on how to do this.