RCW 46.04.1695

"Electric personal assistive mobility device" (EPAMD) means (1) a self-balancing device with two wheels not in tandem, designed to transport only one person by an electric propulsion system with an average power of seven hundred fifty watts (one horsepower) having a maximum speed on a paved level surface, when powered solely by such a propulsion system while ridden by an operator weighing one hundred seventy pounds, of less than twenty miles per hour or (2) a self-balancing device with one wheel designed to transport only one person by an electric propulsion system with an average power of two thousand watts (two and two-thirds horsepower) having a maximum speed on a paved level surface, when powered solely by such a propulsion system, of less than twenty miles per hour.