A lightning rod conducts a positive charge up to meet the negative charge of a lightning strike, allowing the strike to hit the rod and travel through attached wires to an underground connection. This diverts the strike away from a building, preventing or lessening potential damage, according to About.com.
To be most effective, the rods should be placed on the tallest parts of the building. The rods are about 12 inches tall, 3/8 inches in diameter and made of aluminum or copper. Contrary to popular myth, lightning rods do not attract lightning, but merely dispel the strikes, according to Modern Lightning Protection, an installation company.