Rolling sphere method compared for safe lightning protection. At bpe, we can provide you with a lightning protection study for your facility. The rolling sphere method is included in national fire protection association document nfpa 780 standard for the installation of lightning protection systems. For instance, the muchused rolling sphere method see 3, 4 assumes that the protection radius or protection volume are constants, i. Lightning protection and the building envelope page 3 of 6.
Rolling sphere method of lightning protection and shielding for. A sphere with 150ft radius is envisioned rolling across the site and up to the building. The text clearly provided that strike termination devices include air terminals, metal masts, permanent metal parts of. Replaces e1, design to lightning standard, nfpa78008. Wording is changed in various paragraphs from rolling. It uses a statistical based simulation model to assess vulnerability of an installation and performance of the shielding system. The rolling sphere method enables designers to determine where air. Nfpa flashover use the calculators on this tab to determine the flashover distances for the nfpa requirements. Rolling sphere method for lightning protection ecle. Nfpa780 accepts continuous building steel columns as downcomers. Jun 28, 20 it means that the conic and sphere method are useful when we are talking about houses, industrial installations and any kind of infrastructure that is not a high voltage substation. Nfpa 780, standard for the installation of lightning protection systems, delivers a flexible approach to providing applicable safety protocols for lightning hazards based on the use of the building or structure.
A piece of equipment is said to be protected from a. Reflecting the latest protection methods, devices, and safety challenges, the 2017 edition of nfpa 780, standard for the installation of lightning protection systems is the new industry benchmark for protecting lives and property from fire and related dangers associated with lightning events. For example, nfpa 780 uses an r 1 value of 150 feet 46m. The first step to ensuring a facility or asset is lightning protected is to quantify the lightning risk to that facility and its personnel. Zone of protection the formula terms are changed to use the value r. A sphere with 150ft radius is envisioned rolling across the site. Dimension a in both figures is 20 or 25 feet and is the maximum spacing recommended by the nfpa between lightning rods. It can be used in contact with earth but should not be used where runoff contacts steel or aluminum. Nfpa 780 is the north american standard for lightning protection systems lps. Based on nfpa criteria, the report will make one of the following statements.
Modern lightning protection for airports and power plants use the rolling sphere method and place air terminals so that the areas of protection overlap and include any sensitive equipment that would be damaged by a strike. Npfa 780 lpi 175 lightning protection system for ground. It is formulated by correlating the radius of the sphere with the average amount of charge present in the downward lightning leader. Nfpa 780 provides lightning protection system installation requirements to safeguard people and property from fire risk and related hazards associated with lightning exposure. Nfpa 780 code nfpa 780, lightning protection system design. Rolling sphere method the rolling sphere method rsm is one way to determine strike termination placement and the zop of lightning protection systems. And common bonded to the building electrical system in accordance with article 230, 250, 280, 800. Installation of lightning protection systems to nfpa 780ul 96a application standards nfpa 780 and ul 96a cover assessment of risk from lightning and installation of an appropriate lps.
Ul knowledge solutions nfpa 780 and ul 96a lightning. Nfpa 780 draws much from the oldschool system while. Nfpa 780 code nfpa 780, lightning protection system. Report on comments a2007 roc copyright, nfpa nfpa 780. For more information, see user guide for lightning risk calculator. The recommended method of identifying terminal locations by the performance method is by use of the 150ft rolling ball. I have field experience that disputes the equivalence. Designers use the rolling sphere method to help determine where air. The 2020 edition offers stateoftheart provisions for installations, including onsite physical inspections of completed. The distribution of lightning activity may also change, raising the occurrence of lightning in regions that heretofore had little risk. The workshop provides valuable insight on how nfpa 780 and ul 96a relate to each other. Chapter 8 of nfpa 780, titled protection of structures housing explosive materials is written to the lps requirements for ae facilities and contains the more. Based on these parameters, the rolling sphere method can been employed to develop a safety canopy constructed with a geometry of a 45 m 146. The method mostly used to place air terminal is called rolling sphere method and widely explained in nfpa 780.
Rolling sphere method use an imaginary sphere of radius s over the surface of a substation. Rolling sphere method of lightning protection and shielding. In the rolling sphere method, you imagine rolling a sphere of radius d d is the striking distance. A piece of equipment is said to be protected from a direct stroke if it remains below the curved surface of the sphere. Rolling sphere method lightning protection design in florida. Nfpa 780 states, there are some cases where the need for protection should be given serious consideration regardless of the risk assessment. The nfpa recommends a striking distance of 30 m or 46 m. Sep 16, 2012 this animation was created to help illustrate how the rolling sphere method is used to determine protection zones. Ieee guide for direct lightning stroke shielding of substations 1. Lightning protection overview lightning protection institute. This range is based on level iii protection, which is essentially equivalent to the single protection level used in nfpa 780 50 ft rolling ball etc. Mar 03, 2015 training on the rolling sphere method of lightning protection and shielding for substations using ieee std. Nfpa 780 provides the best we know today in theory and technology on protection systems tested by experienced industry professionals in a legally recognized format. Nfpa 780 standard for the installation of lightning.
No known practical method of providing 100% shielding. Similar in principle to bs eniec 62305, though with a single sphere radius of 150 feet. The rolling ball or more correctly the rolling sphere method uses an imaginary. Based on conventional design principles rolling sphere, cone of protection and mesh method as found in as1768, bs6651,iec, cp33 and nfpa 780 precision manufacturing ensures easy assembly and installation ul master label system for npfa components during design, installation and commissioning, our engineers can. Standard for the installation of lightning protection systems. A limitation of using this method as detailed in nfpa 780 is that the rolling sphere method does not account for shorter strike distances than 150 feet 46 m.
The rolling sphere lightning protection method assumes the electricallycharged field that produces a lightning strike has a 150 ft. Included in national fire protection association document nfpa 780 standard for the installation of lightning protection systems, the method is based upon rigorous scientific research, testing with real lightning, and more than two hundred years of proven performance. Pdhonline course e367 2 pdh designing to lightning standard, nfpa 780 2011. Copper and aluminum are the most commonly used metals in a lightning protection system lps. We will examine the rolling ball method after the next sidebar. From 1, the recommended maximum distance for 10 in. Installation of lightning protection systems to nfpa 780ul 96a. Nfpa 780 lighting protection method mike holts forum. What was once referred to as lightning rods are now called air terminals. A limitation of using this method as detailed in nfpa 780 is that the rolling sphere method does not account for shorter strike distances than 150 feet 46 m, which would allow a strike to slip into the protected area, or competitive factors, which make some locations more likely to. The result is a fully compliant nfpa 780 lps that followed the additional guidelines in lpi 175. Fire protection association document nfpa 780 standard for the installation of. Knowing nfpa 780 method of risk assessment study, knowing software method for performing the risk assessment study. Choose the radius of the rolling sphere used in determining the zone of protection.
Standard for the installation of lightning protection systems 2017 datascience. Whereas, the protection angle method is only suitable for the most basic of structuresgeometries, and where the object dimensions do not exceed its comparative rolling sphere radius dimension. Nfpa780 accepts continuous steel handrails as downcomers. Rolling sphere method lightning protection in michigan. Ieee std 9981996, ieee guide for direct lightning stroke. Those points that the rolling sphere touches can be struck, according to this approach. Rolling ball, 30deg, 45deg, 63deg cone of protection. Ul 96a, nfpa 780 and all listed components correctly installed and connected to earth. Tennessee lightning protection rolling sphere method of. Lightning protection and the building envelope page 3 of. Nfpa780 has tables of equivalent aluminum and copper. If lightning hits the structure, it will preferentially strike the rod and be conducted to ground through a wire, instead of passing through the structure, where it could start a fire or cause electrocution.
Enter measurements into the white boxes choose the unit of measurement press tab or enter after entering the final measurement, to generate the result. Lightning protection lightning protection expert information. This method is necessary to calculate the covering of the structure throught rolling sphere method. Buy nfpa 780, standard for the installation of lightning. It contains simplified risk assessment calculations to determine if an lps is recommended for a building. Nfpa 780 2008 edition lightning protection institute. Lightning protection systems design part i electrical. The sphere rolls up and over and is supported by air terminal. These assessment methods take into account lightning frequency, site capture area, type and use of the facility and other factors.
Evaluation of rolling sphere method using leader potential concept. Most lightning protection standards have a risk calculation method for assessing the need for direct strike protection bs 6651, nfpa 780, iec 62305, as 1768, nfc 17102. Nfpa 780 indicates two types of angles, for structures bellow 7,6m would be considered a 63 degrees angle 2 to 1 relation, for structures above 15 m would be considered a 45 degrees angle. Modern lightning protection on recreational watercraft. Standard for the installation of lightning protection. The standard tells us that a zone of protection is provided under the chord of a 150ft rolling sphere. Nfpa 780 provides requirements for lightning protection systems that are based on the cone of protection method or protection angle method and the rolling sphere method. Global warming could increase lightning strikes by 50 percent, according to recently published climatological research. Lightning protection system design and calculations. Rolling sphere method of lightning protection 3d animation. Metals must be high grade to minimize electrical resistance to powerful lightning surges. A lightning rod us, aus or lightning conductor is a metal rod mounted on a structure and intended to protect the structure from a lightning strike. Similar in principle to iecbs en 62305, though with a single sphere.
Jul 28, 2015 global warming could increase lightning strikes by 50 percent, according to recently published climatological research. Nfpa general meeting 65910 new document issued 73010. Requirements for lightning protection systems, or nfpa 780, standard for the. Copper weathers to blend into darkcoloured surfaces and can be treated to accelerate patina. Sls utilizes custom software tools to efficiently perform the risk assessments outlined in nfpa 780 and iec62305. The standard is based upon rigorous scientific research, testing with real lightning, and more than two hundred years of proven performance. I think i would go with a decoy franklin rods and the rolling sphere zone of. Design by fthemes blogger theme by lasantha premium blogger themes windows virtual. Lets focus in the rolling sphere method, where there are different radiuses according to standard iec 62305. Npfa 780 lpi 175 lightning protection system for ground mounts.
Product testing for lightning protection material components in the factory prior to shipment for listing and labeling is handled by underwriters laboratories, inc. In rference of the title of this thread i need sono information about the calculation protection in accordance of nfpa 780. It takes a lightning protection system construction canada. Dimension b in the lower figure is 20 feet and is the maximum spacing between rods located along the edge of the roof. Design to lightning standard, nfpa780 08 thomas mason, p. The course focuses on nfpa 780 chapters 1 through 6 and ul 96a applications and includes detailed guidance on general requirements, miscellaneous structures, special occupancies, and heavy duty stacks. The science of a lightning strike and how to safeguard. The rolling sphere method is included in national fire protection association document nfpa 780 standard for the installation of lightning protection systems for having performed successfully for more than two hundred years.
Guide nfpa 780 1 mast 1 mast 2 masts 2 masts unequal height integral 3 masts 3 masts different heights 4 masts 4 masts different heights multimast single catenary parallel catenaries x catenaries closed end x catenaries open end. Training on the rolling sphere method of lightning protection and shielding for substations using ieee std. In the rolling sphere method, you imagine rolling a sphere of radius d d is the striking distance over the structure being evaluated for lightning vulnerability. Where a product successfully passes ul evaluation it may carry a ul mark appropriate to the testing carried out. The locus of all points traversed by the center of the rolling sphere forms the imaginary capture surface referred to above. Annex m, personal safety, contains much new information. The text clearly provided that strike termination devices include air terminals, metal masts, permanent metal parts of structures, and overhead ground wires.
Some equipment facilities are more at risk from a lightning strike due to many factors such as the the region where the facility is located, the construction of the building and whether or not there are any existing lightning protection devices such as surge protectors and grounding electrodes installed. Software for rolling sphere method of lightning protection. Lightning protection requirements for dod ammunition and. Two down conductors at opposite corners of the roof are shown in. Parts of the building touched by the sphere are at risk. But my field experience, in turn, is disputed by experts in the field whom i respect. The rolling sphere method does not account for shorter strike distances than r 1, which would allow a strike to slip into the protected. The sphere rolls up and over and is supported by lightning masts, shield wires, substation fences, and other grounded metallic objects that can provide lightning shielding. The designer visualizes a sphere with that radius rolling over the surface of the building. Sparkta makes it possible to reduce the final cost of the lightning protection system compared to the designs made by using the rolling sphere method. Knowing iec 623052 method of risk assessment study, knowing nfpa 780 method of risk assessment study, knowing software method for performing the risk assessment study, knowing online calculators method for performing the risk assessment study, know how to size air termination system components. Lightning protection systems design part ii electrical. Rsm involves rolling an imaginary sphere of a prescribed radius over the air termination network.
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