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Types Of Design
Introduction There are basically two types of lightning protection system (LPS) that one can have on a bulding and they are A Faraday Cage System (conventional system) An Early Streamer Emmiter (ESE) System It is important to note that ADS does not advocate one system over the other. Both systems have their advantages and disadvantages and ADS will recommend the optimum design for a particular senario. Faraday Cage System This would be considered by many to be the conventional system. It consists of laying out a 25X3mm metal tape grid on the roof. The size of the grid is determined by a risk assessment which is set out in the standard covering this type of system, namely IS EN 62305 2006. The metal grid or air termination network (ATN) is connected to the down conductors which consists of a metal tape fixed to the walls travelling vertically to the ground. These down conductors are then in turn connected to the earth rods. The earth rods are typically 2.4 M long and are driven vertically into the ground as close to the building as possible. The spacing of the earth terminations is again determined by the risk assessment. The standard permits the use of structural elements to be incorporated into the LPS design. This type of lightning protection system is covered by "IS EN 62305 2006 Protection Against Lightning". Early Streamer Emmitter (ESE) The above mentioned standard (IS EN 62305) is entitled Protection Against Lightning. However, this is a little misleading as it implies that this is THE standard for lightning protection. This is not entirely true. IS EN 62305 makes no provision for other types of lightning protection systems which have become excepted world wide within the industry. One such system is the early streamer emmitter lightning protection system. This system consists of a device which is mounted in a pole above the highest point (approx 2 Metres) with a down conductor running down the building and termination at an earth point. The device works by providing a preferential path for the lightning to take. The device does not attract nor create lightning, nor does any lightning protection system for that matter. As a result of this preferential path the device provides an area or zone of protection which, depending on many factors, can be quite large. There are many devices/products on the market but ADS believe that the product we install provides the best protection, a product that has been installed world wide. The products are certified to NFC 17-102. This is an International French product standard. Again, it is important to note that ADS does not advocate one system over the other. Both systems have their advantages and disadvantages and ADS will recommend the optimum design for a particular senario. |
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