3-Slot vs. 4-Slot Dryer Outlets - The Spruce Electrical dryers can use power cords with three-prong or four-prong plugs; these plug into dryer outlets that have either three slots or four slots. What Is the Difference Between 3-Slot and 4-Slot Dryer Outlets? By Timothy Thiele. Updated 10/29/18. Pin Share A three-wire dryer outlet has two "hot" slots and neutral/ground slot. ThisChanging a Dryer Cord · Wiring a New Outlet Wiring a Dryer Power Cord - Ask-The-Electrician Wiring a Dryer Power Cord. Dave's Reply: Your welcome Tammy, I'm glad the dryer wiring diagram has helped you! 3 Wire Dryer Cord to a 4 Wire Dryer Cord. I need to convert an old 3 wire outlet for a new 4 wire dryer what is the easiest thing to do with this problem.