People generally think of lightning damage as what happens at the point where a cloud-to-ground strike hits a tree, structure or elevated wiring. Unless the struck items are protected from lightning, the results of the strike are often visible and lasting. However, the lightning current pulse continues into conductive parts of the structure, cables, and even underground wiring and pipes. Because the initial lightning impulse is so strong, equipment connected to cables a mile or more from the site of the strike can be damaged.
The most common damage arises from a lightning strike to the network of power, phone and cable television wiring. This network, especially if it is elevated, is an effective collector of the lightning surges. The wiring then conducts the surges directly into the residence and to the connected equipment. Lightning can also travel through the ground (soil), reaching underground cables or pipes. This is another route for lightning to come into a building and can also damage the cables.
The second-most common mode results from strikes to or near the external wiring – common to most suburban and rural houses. Air conditioners, satellite dishes, exterior lights, gate control systems, pool support equipment, patios and cabanas, phone extensions, electronic dog fences and security systems can all be struck by lightning. The lightning surges will then be carried inside the house by the wiring.
To take maximum precautions, unplug as many electrical and electronic appliances as possible if there is a storm brewing.
Remember to check both the electric sockets and the telephone and cable television connections. Surge protectors are a good aid in protecting your equipment, but in proportion to the very low risk involved, these can be very expensive. Nothing can withstand a lightning strike – it is best to totally unplug.