Voltages induced on overhead multiconductor lines by lightning strokes

The voltages on an untransposed multiconductor line over a perfect earth, induced by the return stroke of lightning, are analysed. The magnitude of the induced voltage on a multiconductor line is higher than that on a single-conductor line of the same height above earth. Earth wires reduce this magnitude somewhat, but not enough to consider them as an effective means of protection. Shielding against induced overvoltages caused by lightning may be accomplished by other means, such as protector tubes and automatic reclosers.