Abstract: A fencepost insulator that can be quickly and easily mounted on a wire of an electric fence for providing an electrically-resistive barrier between the electrified wire and a conductive fencepost. The insulator is a unitary, roll-shaped segment of electrically-resistive material with a loose spiral-shaped cross section. The insulator is installed by manually rolling the insulator onto a wire, thereby allowing the insulator to be conveniently installed at any location along the length of the wire.