An electric fence insulator is formed as a flexible band of material with an opening along a lateral periphery. The band is flexed to position around the perimeter of a fence post along a length of the fence post as determined by the length of the insulator. The insulator provides electrical insulation between an electrically energized fence wire and a point of contact of the wire with a grounded fence post. The insulator includes a fastener at the opening to close to a secure position using a simple clipping motion after the insulating band is positioned on the fence post at a selected height. The insulator forms a minimal lever arm between the fence post and the energized wire. The insulator may be retrofitted to existing installations with fence wire already installed without a need to access the fence post from the top to the section requiring electrical insulation.
