Horn Gap Type Lightning Arrester: It consists of two horn shaped metal rods A and B separated by a small air gap. The horns are so connected that distance between them gradually increases towards the top. One end of the horn is connected to the line through resistance and choke coil while other end is effectively earthed. The resistance and inductance limits the current flow at normal frequency and does not allow the transients. Under normal operating conditions the gap G is non-conducting. On occurrence of over voltage, spark takes place across the gap and high voltage is diverted towards earth for safety of equipment. Arc being hot, moves up naturally along the horns. So it is elongated and naturally quenched.