EMP pulses from lightning are almost always induced on to utility (any kind - power, telecommunications, etc...) wiring that runs through areas where lightning occurs. It is the combination of very high levels of magnetic flux and the great length of cable that is exposed that results in the massive energy transfer. The only way to mitigate resultant surges is to use a secondary surge suppressor at the main electrical panel board and surge suppression at the equipment that we want to protect. These usually consist of voltage clamps that permit relatively safe levels (up to about 200 volts rms) to exist on the circuit. Most often these are MOVs, but can also include high current zener diode arrays and gas discharge tubes. It’s important to know that these devices are all sacrificial in nature, and need to be checked for functionality on a regular basis. It’s also important to have your home electrical system inspected for damage whenever a major surge is experienced, as extremely large amounts of energy can be dissipated in wiring, receptacles, circuit breakers, etc in the event of a major surge, causing permanent damage and potentially rendering the electrical system a fire hazard. The best measure of protecting our valued equipment is disconnecting from all sources of surge ingress in advance of lightning storms.
