Did you know that last year, in the United States, property loss due to lightning strikes exceeded one billion dollars? The average homeowner’s insurance paid $4,296 per lightning claim and an average of two hundred fifty thousand insurance claims were filed strictly due to lightning. In January 2003, the American Meteorologist Society issued a bulletin endorsing the lightning protection requirements embodied in the National Fire Protection Association Standard 780.
Stating, “It is now well established that properly installed and maintained lightning rod based protection systems significantly decrease lightning damage.
” The only true way to protect a structure from a direct lightning strike is with a lightning protection system. A lightning protection system, with proper installation can save lives, protect structures, and provide peace of mind. To understand lightning protection, you first need to understand lightning. Lightning, by definition, is the discharge of static electricity from cloud-to-ground.
Lightning is the energy created by friction from the rise and fall of hot and cold air masses in the clouds.
This energy, which is only visible as lightning, retains a negative charge. To equalize, this negative charge must contact a positive charge, which is held by ground. The positive charge and the negative charge seek the best route to meet and dissipate; meaning that lightning is only looking for a way to obtain ground. Lightning decides on a target no more than 500 feet prior to striking and does not discriminate on what it strikes.
Lightning protection systems provide an efficient path for lightning to reach the ground safely, without destroying structures. The system does not attract lightning, nor deter, but rather acts as a canopy of protection. Lightning protection systems are interconnected to form a “cage” around the perimeter of the structure. Every element of the lightning protection system has to connect to form common grounding. There are five elements that make up a lightning protection system. The five elements are lightning rods, cable, ground rods, bonding materials and surge protection.
The lightning rods are positioned at the very top of the lightning protection system. Their function is to take the direct strike of the lightning bolt. Lightning rods are constructed of copper or aluminum to withstand the electrical current as a result of a direct strike. Depending on the specifications of the structure, the length of the lightning rods varies, however; the width of the lightning rods is usually the same diameter of an ordinary pencil. The rods aren’t very big; however, they can withstand the power of a direct lightning strike.
The second element of a lightning protection system is the cable, which is also constructed of copper or aluminum materials. The cable’s function is to “transport” the electrical current from the lightning rods to the ground rods. The cable is routed around the perimeter of the structure with “downleads” occurring at different points of the structure, depending on the specifications. “Downleads” are when the cable is run down the structure to the ground rods. Ground rods are the very bottom of the lightning protection system.
They take the electrical current of the lightning into the ground to equalize or dissipate. This means that the electrical current is now neutralized. Ground rods are very similar to lightning rods, however, the ground rods can be ten feet long and are buried at least six feet below grade. In rocky soil, installation can be a particularly hard. Bonding of the lightning protection system refers to making sure that all utility entrances are protected along with the structure. Gas lines, water lines, and electrical lines all have to be connected.
Surge Protection is the last element of the lightning protection system. As lightning protection provides structural protection, surge protection protects sensitive electronics and other utility entrances, such as telephone, cable, and electrical outlets. Surge protection is an important part of the lightning protection system puzzle. Lightning protection systems are an essential element to protecting every structure, but are different for every structure resulting in making a lightning protection contractor a very specialized trade.
Residential lightning protection is placing lightning protection on private homes. A lightning protection system has two different types of residential systems; concealed or exposed. Concealed system installations are included during the construction of the home. The concealed system is designed to be hidden; as the name implies. During different stages of construction, the lightning protection installation technicians run the cable within the framework of the home. Also the cable is run up through the roof in special constructed “thru-roof” products.
The lightning protection system works without being seen. Some individuals wonder how lightning can run along the cable between the walls of a home without starting a fire. The lightning is traveling so fast along the cable with no friction and doesn’t enough time for a fire to start. Exposed lightning protection systems installations are completed after construction. Cable is run on the outside of the roof and walls, however; you can paint the cable to match the color of the exterior to make the cable blend for a more aesthetically pleasing affect.
The paint will not hinder the cable’s ability to carry the electrical current. Also cable can be run down along the rain gutters for even more concealment Commercial lightning protection systems are similar to residential, they both have the same principles, but they are installed on commercial structures. The only difference is the height, which has different standards from the normal residential homes. There are two types of lightning protection systems. The first is a class I structures have a height of 75 feet or below and only require a “standard” lightning protection system.
The second is a class II structure, usually known as high rises or sky scrapers, have a height of 75 feet or above. These buildings have to be specified with what is called an “Intermediate Loop. ” An Intermediate Loop consists of a “standard” lightning protection system but has an additional loop of cable run around the middle of the height of the building. The loop consisting of running cable around the building is connected to all the downleads. The loop guarantees the lightning bolt a continuous path without friction to get down to the ground rods.
Also, some Class II buildings require a “Ground Loop. ” This loop is a mirror of the “Intermediate Loop,” but is buried below the grade of the commercial building. This loop is also connected to all the ground rods, but is not visible because it is underground. Just as the intermediate loop, this ground loop provides more options for the lightning to dissipate. As stated before, lightning is only looking for a path to get to ground and equalize. Lightning protection systems allow this to happen in a non-destructive manner without devastating the building materials of commercial or residential structures.