Arcing horns

Arcing horns (sometimes arc-horns) are projecting conductors used to protect insulators on high voltage electric power transmission systems from damage during flashover. Overvoltages on transmission lines, due to atmospheric electricity, lightning strikes, or electrical faults, can cause arcs across insulators (flashovers) that can damage them. The horns encourage the flashover to occur between themselves rather than across of the surface of the insulator they protect. Horns are normally paired on either side of the insulator, one connected to the high voltage part and the other to ground. They are frequently to be seen on insulator strings on overhead lines, or protecting transformer bushings.