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. The text clearly provided that strike termination devices include air terminals, metal masts, permanent metal parts of. Nfpa 780 is the north american standard for lightning protection systems lps. Nfpa 780 draws much from the oldschool system while. Nfpa general meeting 65910 new document issued 73010. Mar 03, 2015 training on the rolling sphere method of lightning protection and shielding for substations using ieee std.
Parts of the building touched by the sphere are at risk. The rolling sphere method is included in national fire protection association document nfpa 780 standard for the installation of lightning protection systems. The 2020 edition offers stateoftheart provisions for installations, including onsite physical inspections of completed. 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. The rolling sphere method does not account for shorter strike distances than r 1, which would allow a strike to slip into the protected. I think i would go with a decoy franklin rods and the rolling sphere zone of. Npfa 780 lpi 175 lightning protection system for ground. 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. 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. Rolling sphere method lightning protection design in florida. This method is necessary to calculate the covering of the structure throught rolling sphere method. A piece of equipment is said to be protected from a. The recommended method of identifying terminal locations by the performance method is by use of the 150ft rolling ball.
The locus of all points traversed by the center of the rolling sphere forms the imaginary capture surface referred to above. 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. Ieee guide for direct lightning stroke shielding of substations 1. 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. Training on the rolling sphere method of lightning protection and shielding for substations using ieee std. Similar in principle to bs eniec 62305, though with a single sphere radius of 150 feet. 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. In rference of the title of this thread i need sono information about the calculation protection in accordance of nfpa 780. Requirements for lightning protection systems, or nfpa 780, standard for the. Zone of protection the formula terms are changed to use the value r. Nfpa780 accepts continuous steel handrails as downcomers. 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.
It contains simplified risk assessment calculations to determine if an lps is recommended for a building. Based on nfpa criteria, the report will make one of the following statements. But my field experience, in turn, is disputed by experts in the field whom i respect. 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. Software for rolling sphere method of lightning protection. Rolling sphere method of lightning protection and shielding. A sphere with 150ft radius is envisioned rolling across the site and up to the building.
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. 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. What was once referred to as lightning rods are now called air terminals. At bpe, we can provide you with a lightning protection study for your facility. Lightning protection systems design part ii electrical. 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. Lightning protection systems design part i electrical. 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. The rolling ball or more correctly the rolling sphere method uses an imaginary. Lightning protection and the building envelope page 3 of 6. In the rolling sphere method, you imagine rolling a sphere of radius d d is the striking distance. Rolling sphere method use an imaginary sphere of radius s over the surface of a substation. 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.
Ieee std 9981996, ieee guide for direct lightning stroke. Lightning protection overview lightning protection institute. Tennessee lightning protection rolling sphere method of. Design to lightning standard, nfpa780 08 thomas mason, p. There are many formulas to determine the radio of the sphere but the ice uses the following equation. Fire protection association document nfpa 780 standard for the installation of. Rolling ball, 30deg, 45deg, 63deg cone of protection.
It takes a lightning protection system construction canada. 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. These assessment methods take into account lightning frequency, site capture area, type and use of the facility and other factors. Metals must be high grade to minimize electrical resistance to powerful lightning surges. Two down conductors at opposite corners of the roof are shown in. 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. Design by fthemes blogger theme by lasantha premium blogger themes windows virtual. The rolling sphere method accounts for all types and combinations of structures in a more elegant and technically secure way. Nfpa 780 code nfpa 780, lightning protection system.
Pdhonline course e367 2 pdh designing to lightning standard, nfpa 780 2011. Lightning protection and the building envelope page 3 of. Rolling sphere method compared for safe lightning protection. Installation of lightning protection systems to nfpa 780ul 96a. Dimension b in the lower figure is 20 feet and is the maximum spacing between rods located along the edge of the roof. 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. Nfpa780 has tables of equivalent aluminum and copper. The text clearly provided that strike termination devices include air terminals, metal masts, permanent metal parts of structures, and overhead ground wires. Nfpa780 accepts continuous building steel columns as downcomers. Wording is changed in various paragraphs from rolling. For example, nfpa 780 uses an r 1 value of 150 feet 46m.
It is formulated by correlating the radius of the sphere with the average amount of charge present in the downward lightning leader. Rolling sphere method the rolling sphere method rsm is one way to determine strike termination placement and the zop of lightning protection systems. Ul knowledge solutions nfpa 780 and ul 96a lightning. The nfpa recommends a striking distance of 30 m or 46 m. Buy nfpa 780, standard for the installation of lightning. Rolling sphere method calculator by nestor h camerino jr, 25 april 20 revision. The sphere rolls up and over and is supported by air terminal. Copper weathers to blend into darkcoloured surfaces and can be treated to accelerate patina. Knowing nfpa 780 method of risk assessment study, knowing software method for performing the risk assessment study.
The distribution of lightning activity may also change, raising the occurrence of lightning in regions that heretofore had little risk. Nfpa 780 states, there are some cases where the need for protection should be given serious consideration regardless of the risk assessment. Lets focus in the rolling sphere method, where there are different radiuses according to standard iec 62305. I have field experience that disputes the equivalence. Copper and aluminum are the most commonly used metals in a lightning protection system lps. Global warming could increase lightning strikes by 50 percent, according to recently published climatological research. And common bonded to the building electrical system in accordance with article 230, 250, 280, 800.
Similar in principle to iecbs en 62305, though with a single sphere. From 1, the recommended maximum distance for 10 in. The rolling sphere lightning protection method assumes the electricallycharged field that produces a lightning strike has a 150 ft. The result is a fully compliant nfpa 780 lps that followed the additional guidelines in lpi 175. 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. 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. Dimension a in both figures is 20 or 25 feet and is the maximum spacing recommended by the nfpa between lightning rods. Report on comments a2007 roc copyright, nfpa nfpa 780.
It uses a statistical based simulation model to assess vulnerability of an installation and performance of the shielding system. Those points that the rolling sphere touches can be struck, according to this approach. Lightning protection systems have their own terminology, which is defined in chapter 3. Nfpa 780 lighting protection method mike holts forum. 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. The rolling sphere method enables designers to determine where air. Ul 96a, nfpa 780 and all listed components correctly installed and connected to earth.
A sphere with 150ft radius is envisioned rolling across the site. Nfpa 780 2008 edition lightning protection institute. Standard for the installation of lightning protection systems 2017 datascience. Nfpa 780 standard for the installation of lightning. The first step to ensuring a facility or asset is lightning protected is to quantify the lightning risk to that facility and its personnel. Choose the radius of the rolling sphere used in determining the zone of protection. The method mostly used to place air terminal is called rolling sphere method and widely explained in nfpa 780. Replaces e1, design to lightning standard, nfpa78008. Npfa 780 lpi 175 lightning protection system for ground mounts. Standard for the installation of lightning protection systems.
Lightning protection requirements for dod ammunition and. The standard is based upon rigorous scientific research, testing with real lightning, and more than two hundred years of proven performance. Evaluation of rolling sphere method using leader potential concept. 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. For instance, the muchused rolling sphere method see 3, 4 assumes that the protection radius or protection volume are constants, i.
Rolling sphere method of lightning protection 3d animation. Rsm involves rolling an imaginary sphere of a prescribed radius over the air termination network. 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. The workshop provides valuable insight on how nfpa 780 and ul 96a relate to each other. Nfpa 780 provides lightning protection system installation requirements to safeguard people and property from fire risk and related hazards associated with lightning exposure. Designers use the rolling sphere method to help determine where air. 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. The science of a lightning strike and how to safeguard. 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. For more information, see user guide for lightning risk calculator.
The standard tells us that a zone of protection is provided under the chord of a 150ft rolling sphere. Annex m, personal safety, contains much new information. Jul 28, 2015 global warming could increase lightning strikes by 50 percent, according to recently published climatological research. 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. A piece of equipment is said to be protected from a direct stroke if it remains below the curved surface of the sphere. Sep 16, 2012 this animation was created to help illustrate how the rolling sphere method is used to determine protection zones. 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. Rolling sphere method lightning protection in michigan. Lightning protection system design and calculations. Nfpa 780 code nfpa 780, lightning protection system design. Rolling sphere method of lightning protection and shielding for.
Rolling sphere method for lightning protection ecle. No known practical method of providing 100% shielding. 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. It can be used in contact with earth but should not be used where runoff contacts steel or aluminum. Modern lightning protection on recreational watercraft. Nfpa flashover use the calculators on this tab to determine the flashover distances for the nfpa requirements. Sls utilizes custom software tools to efficiently perform the risk assessments outlined in nfpa 780 and iec62305.
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