~ National Lightning Safety Institute ~

General Interest #2

What happens when lightning strikes a vehicle? The answer, gleaned from anecdotal observations, is all the way from "nothing" to "Wow! What a mess. . . my car is a disaster."

Electrically speaking, at lightning's higher frequencies, currents are carried mostly on the outside of conducting objects. A thick copper wire or a hollow-wall metal pipe will carry most of the lightning on outer surfaces. This phenomenon is called Skin Effect. The same holds true for lightning when it strikes metal vehicles: the outer surface carries most of the electricity. The persons inside this steel box can be likened to protected by a partial Faraday Cage.

But, consistent with lightning's capricious nature, situations alter results. Is the car dry or wet? If the car is made of fiberglass (a poor conductor) or a convertible, Skin Effect principles may not work. [Corvette and Saturn owners please note.]

Some general recommendations include:

1. Personal Safety Issues: Reported incidents and related injuries make it clear that a person inside a fully enclosed metal vehicle must not be touching metallic objects referenced to the outside of the car. Door and window handles, radio dials, CB microphones, gearshifts, steering wheels and other inside-to-outside metal objects should be left alone during close-in lightning events. We suggest pulling off to the side of the road in a safe manner, turning on the emergency blinkers, turning off the engine, putting one's hands in one's lap, and waiting out the storm.
   
2. Heavy Equipment: Backhoes, bulldozers, loaders, graders, scrapers, mowers, etc. which employ an enclosed rollover systems canopy (ROPS) are safe in nearby electrical storms. The operator should shut down the equipment, close the doors, and sit with hands in lap, waiting out the storm. In no circumstances, during close-in lightning, should the operator attempt to step off the equipment to ground in an attempt to find another shelter. Very dangerous Step Voltage and Touch Voltage situations are created when a "dual pathway to ground" is created. Lightning voltages will attempt to equalize themselves, and they may go through a person in order to do so.
   Smaller equipment without ROPS is not safe. Small riding mowers, golf cars, utility wagons are examples. Rubber tires provide zero safety from lightning. After all, lightning has traveled for miles through the sky: four or five inches of rubber is no insulation whatsoever. People should safely abandon this machinery and get into a safe shelter.
   
3. School buses. Metal buses are good Faraday Cages. Make sure all windows are closed and the "hands on laps" rule is observed. Pull over and wait out the storm.
   
4. Damage. Reported damage to vehicles includes pitting, arcing, burning on both exterior and interior places. See the below photographs, courtesy of Mr. Brown, of his Jeep Cherokee which was struck by lightning. Cases have been reported of total destruction of vehicle wiring, and associated electrical and electronic systems. Cases from police departments report bad burns to the hands and mouth where officers were using radio microphones when their vehicles were struck. Cases describe total blow-out of all four tires in passenger cars. A video in our NLSI library shows a station wagon being struck by lightning in a heavy rain storm, with no damage whatsoever occurring.

Strike near hatchback

close-up or strike

strike at roof

roof strike closer to front	close-up

strike on wheel

close-up strike near axel