Nearby lightning strikes will cause a fast moving electromagnetic wave to radiate out in all directions. There can be huge amounts of energy coupled into any wires that lie in its path. This will happen regardless if the wires are overhead on telephone poles or buried underground. A lightning strike one mile away will produce a 70V transient on overhead wires; if the strike is only 500 feet away, the transient will reach 10,000V. Any item connected to these wires will need protection from the overvoltage event to prevent certain damage.