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Burj-Khalifa, lightning Prevantion System

 
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B.V.Harsoda
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PostPosted: Mon Nov 26, 2012 2:59 pm    Post subject: Burj-Khalifa, lightning Prevantion System Reply with quote

Burj-Khalifa, lightning Prevantion System  
Links:-
http://burj-khalifa.eu/tourist-attractions/unique-sensor-system-deflects-lightning-from-burj-khalifa

http://gulfnews.com/business/general/unique-sensor-system-deflects-lightning-from-burj-khalifa-1.580777

Regards,
Er. B. V. Harsoda
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B.V.Harsoda
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Joined: 19 Jan 2009
Posts: 2321
Location: RAJKOT,GUJARAT, INDIA

PostPosted: Wed Dec 05, 2012 5:33 pm    Post subject: Reply with quote

Lightning Protection Institute

The Lightning Protection Institute is a not-for-profit organization dedicated to ensuring that today's lightning protection systems are of the best possible quality—in design, materials and installation—so that precious lives and property can be protected from the damaging and costly effects of one of nature's most exciting phenomena: lightning.

Link:-
http://www.lightning.org/?page=home



Interesting FAQ about lightning protection from above link:-

I have a handrail that runs around the perimeter of a six story building. The handrail is 1’ 4" above the parapet. The top of the rail is 6" wide by 3/4" thick flat rail. Can I use this for lightning protection? Can I add short rod points to the top of the rail?


NFPA 780 allows the use of metal 3/16" thick as a strike termination device and as a substitute for cable conductor in a lightning protection system. 3/16" thick metal will not burn through when lightning attaches, and it has sufficient free available electrons to route lightning to a grounding system. Your handrail, which projects above the minimum of 10" for an air terminal, would protect the entire perimeter that it surrounds without addition of terminals or a top circuit. This may not be sufficient to protect the entire mid-roof area, since open areas exceeding 50 ft. by 50 ft. may require additional protection. HVAC units or other roof mounted bodies may extend to a height that requires their protection or interconnection with the system. Your handrail may be continuous with building structural steel that extends the system to near grade where a lightning protection ground system may be added, or if this is a poured concrete structure you may need to extend downlead cables from the handrail down to a grounding system. Of course, bonding of other building grounded systems to the lightning protection system and surge suppression for incoming energized lines is a requirement for complete protection. Please refer to one of our member companies for a complete design and pricing information.



Is an architect required to consider lightning safety when designing a structure?

Whether or not something is required in building standards depends on the requirements of the local authority having jurisdiction. In many cases this is an entity like city or county government and it is totally dependent on what Codes or Standards that body has adopted. There is no "national" law requiring lightning protection. There are some state laws regarding particular types of occupancies - for example, Florida requires lightning protection on health care facilities. The National Fire Protection Assoc. NFPA publishes a Standard for the Installation of Lightning Protection Systems #780 which can be adopted by any jurisdiction just like any other Code or Standard of practice. The National Electrical Code (NEC or NFPA #70) & Life Safety Code (NFPA # 100) are a couple of the better known documents published by NFPA along with literally hundreds of other documents in the fire safety field. None of these is required unless some authority has adopted them specifically into local law. NFPA 780, the lightning protection document is a stand-alone document that is not required by other building Codes, but is left to local option. That doesn't mean that having a working knowledge of these codes and standards isn't a good idea if you are a professional. Architects have a code of ethics just like any other professional which should require them to make clients aware of any product, service or system that may be to their benefit. In many cases an architectural firm may have a list of various items to review with prospective clients early on in the planning stage of a project. Based on this type consultation any system not covered automatically by law may be valued in or out of a project to the satisfaction of the customer. In areas of the country subject to high lightning activity, or in construction occupancies where evacuation is difficult, lightning protection would be an important consideration on any project.



What does the National Electric Code (NEC) say about lightning protection for buildings? Is it only required for certain types of facilities?

The National Electrical Code is NFPA Document #70, as the Lightning Protection Standard is NFPA #780. These are separate documents available for adoption by the "local authority having jurisdiction" for construction projects in their locale. In many locations NFPA 70 (NEC) is adopted, but #780 is not - it is an option. The NEC does not require lightning protection, although it does reference 780 in several sections. Coordination generally exists between the Committees charged with keeping the documents updated. NEC references the fact that an electric service shall have a ground and lightning protection systems shall have separate grounds. NEC references the fact that when there is a 780 lightning protection system the grounds shall be interconnected with the electrical ground. NEC addresses surge suppression as an option, but wording is to be added to clarify that when a 780 lightning protection system is installed, the surge is required by that Standard. Items such as ground terminal devices are coordinated between documents, so that the same products are used in similar soil types. We would presume that since lightning risk assessment is determined through Annex L of the #780 document, and there are locations without much lightning activity, it would be difficult to require lightning protection everywhere or even on specific structures everywhere in a document like NEC. This would make the NEC document not as useful in certain areas.

Is lightning protection required for metal bleachers located at a high school football stadium? There are size tall lighting standards, three per each side of the stadium that are 80' high. There is a press box on one set of the bleachers and the top of it is +/- 33' above finish grade.

he question of whether lightning protection is "required" or not depends on local option. The lightning protection Standard is a building code, and would be subject to adoption by the "local authority having jurisdiction." Since lightning protection is a separate Standard, not a part of the Life Safety Code or the National Electrical Code, it would have to be specifically identified, and in most jurisdictions it is not. It is the reference source if someone chooses the option of providing lightning protection for a structure. In the case of metallic bleachers, it is normally appropriate if you choose protection to provide lightning attachment points above and around the bleachers, and then ground the bleachers. Zones of protection are defined in the Standards based on a 150 ft. radius sphere model. For example, when you place a 150 ft. radius arc tangent with the top of a protected light standard, and tangent with the ground - the area under the arc is considered protected from lightning strikes. Any area breaking this arc is still subject to a direct strike. Therefore, it makes a difference what the relative heights of objects, their proximity, and their total extension away from a protected body may be. You may find that by protecting the light standards and the press box, you have created a protected zone inclusive of the bleachers. Or, you may need to add additional protected light standards (or equivalent protected masts) to provide full protection. There are stadiums with seating areas so extensive that it becomes impossible to provide protection from this "mast-style" configuration. In those instances, an overhead ground conductor, similar to the protection provided over power transmission lines, run between the masts over the bleacher area may provide a more inclusive protected area. Obviously this is something that needs to be reviewed and designed to meet the site conditions. We do not have that engineering capability in this office. You may wish to contact one of our member companies for a design and price structure on the necessary system components for protection. Please click here to search for installers by state.
  
Regards,
B. V.Harsoda
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B.V.Harsoda
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Joined: 19 Jan 2009
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Location: RAJKOT,GUJARAT, INDIA

PostPosted: Wed Dec 05, 2012 6:16 pm    Post subject: Reply with quote

More Useful Link about stuck by lightning:-

http://www.struckbylightning.org/

Regards,
B. V. Harsoda
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