One lightning rod, one safety
2008-08-05

A lightning bolt struck 91 auto racing fans at a racetrack in Norway AUG.2, and 45 people were taken to hospital with minor burns, police said. Lucky, no one was seriously injured. SAO PAULO, Brazil (AP) AUG.2 - Brazilian airport officials say lightning struck a passenger plane as it readied for takeoff from Brazil's southern city of Curitiba. Infrared airport authority spokeswoman Denise Bandeira said none of the 46 passengers aboard the TAM Airlines plane were hurt. The aircraft was undamaged August 3, Belgium, a lightning bolt struck a car recycle bin, trigger fire, the loss is also unclear.  And do you know the lightning discharges can range up to 200 million volts. Domestic supplies are only 240 volts. In fact, lightning caused many accidents to people's lives and property brought about great harm in the history. Many people called the Lightning a "toothless tiger" and "Lightning killer", afraid, and did not dare go out in a lightning storm day. In fact, the Lightning is too terrible to have no way to deal with, such as the lightning rod, is a very well equipped to deal with thunder and lightning.  A lightning rod is a single component in a lightning protection system. In addition to rods placed at regular intervals on the highest portions of a structure, a lightning protection system typically includes a rooftop network of conductors, multiple conductive paths from the roof to the ground, bonding connections to metallic objects within the structure and a grounding network. The actual rooftop lightning rod is a metal strip or rod, usually of copper or aluminum. Lightning protection systems are installed on structures, trees, monuments, bridges and even water vessels to protect from lightning damage. Individual lightning rods are sometimes called finials, air terminals or strike termination devices. Lightning damage has been with humanity since people started building structures. Early structures made of wood and stone tended to be short and in valleys and as a result lightning hit rarely. As buildings became taller, lightning became a significant threat. Lightning can damage structures made of most materials (masonry, wood, concrete and even steel) as the huge currents involved can heat materials, and especially water to high temperatures causing fire, loss of strength and explosions from superheated steam and air.  In the United States, the pointed lightning rod conductor, also called a "lightning attractor," was invented by Benjamin Franklin in1752 as part of his groundbreaking explorations of electricity. Franklin speculated that, with an iron rod sharpened to a point at the end. In the 19th century the lightning rod became a symbol of American ingenuity and a decorative motif. Lightning rods were often embellished with ornamental glass balls. The ornamental appeal of these glass balls has also been incorporated into weather vanes. Lightning rod’s working principle is: A lightning storm, a live high above the clouds, Thunder needle and sensors have been at the top of tall buildings on the large number of charge, because lightning rod is a sharp needle, and when the electrostatic induction, the conductor always gather the most sophisticated of charge. In this way, lightning rod gathers the majority of charge. Lightning rod form a capacitor with these clouds, and it is more pointed, the capacitor that is the polarization of the board are very small, very small capacitance, which means it can accommodate the charge very little. But it also brought together a large number of charge, so when the clouds on the charge more, the air of the lightning rod between the cloud can easily be penetrated, become a conductor. In this way, charged clouds and lightning rod formation pathway, and the lightning rod was grounded, lightning rod will be able to lead the charge clouds into the earth, to not pose a risk of high-rise building to ensure its security. Why lightning rod mounted on the top of the building? Charged clouds, is the first top-down operation, the lightning rod in height, will be discharge the charge in the clouds first , after exposure to house-time, it basically no or only a small portion charge, but not dangerous.  Because the structure and role of lightning rod, we must pay special attention to the lightning rod to maintain good electrical conductivity. Once a connection was bad or broken, the period over where broken will be an isolation conductive system.