Do I really need a three-prong outlet? June 30, 2023 02:09 Updated Yes, the Gradient unit requires a three-prong outlet. Related articles What happens if I don't use a three-prong outlet? The cord isn't long enough. What should I do? What are the dimensions of the Gradient heat pump? My unit is dripping a lot of water outside. What should I do? Why do I need a three-prong outlet?