Rolling sphere method
- Thread starter arunavac
- Start date
- Status
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
I was going to close this, by virtue of its having no relationship to the electrical industry. Then I looked up NFPA 780. It has to do with lightning protection systems. So it is related. But it would have been helpful to say a little more, and to save us the trouble of trying to understand the question.
That said, I no nothing about lightning protection. Perhaps some other member can assist.
That said, I no nothing about lightning protection. Perhaps some other member can assist.
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
Is that one of those "umbrella's" that they use now thats supposed to dissapate lightning, instead of drawing it?
- Location
- Illinois
- Occupation
- retired electrician
It looks like the zone of protection goes straight down the stack untill it reachs the 46m diameter sphere that is touching the stack and then all of the area under the sphere is protected. See NFPA 480, 4.7.3.2. You can view that document online for free at NFPA.org. You do have to register to view it.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
You can get free information on lighting protection and grounding: http://www.usda.gov/rus/electric/pubs/1724e300/1724e300.pdf
Last edited:
- Location
- Illinois
- Occupation
- retired electrician
The size of the sphere for the rolling sphere method is specified at a diameter of 46m in NFPA 780.
ohmhead
Senior Member
- Location
- ORLANDO FLA
Rolling ball theroy
Rolling ball theroy
Well we had a job with large cooling towers and they used a program to simulate a rolling ball at a certain speed off the top of each tower this ball would roll off and when it hit the ground earth that was your area of protection .Meaning ligthing protection of that covered area just thought id add this to the posts .sorry if i offended any one just a thought .take care
Rolling ball theroy
Well we had a job with large cooling towers and they used a program to simulate a rolling ball at a certain speed off the top of each tower this ball would roll off and when it hit the ground earth that was your area of protection .Meaning ligthing protection of that covered area just thought id add this to the posts .sorry if i offended any one just a thought .take care
- Location
- Illinois
- Occupation
- retired electrician
That would not be in compliance with the method stated in NFPA 780, Standard for the Installation of Lightning Protection Systems.
ohmhead
Senior Member
- Location
- ORLANDO FLA
Rolling ball theory
Rolling ball theory
Well so your saying that the engineering firm at this project is not performing by NFPA regs or rules . may we explain how it works . This program simulates a structure of any type size that you input to program it simulates a round ball at a rate of speed pitched off top /center of structure at speed then its propelled out off edge of structure and now air born starts to drop to earth now that area of protective cover is in that scope of the rolling ball off top of stucture the canopy of protection . I tell the electrical engineers Black &vech that its a issue and we are not going by the NFPA . take care i just knew i should not have posted this but we call it the Rolling Ball Theory
Rolling ball theory
Well so your saying that the engineering firm at this project is not performing by NFPA regs or rules . may we explain how it works . This program simulates a structure of any type size that you input to program it simulates a round ball at a rate of speed pitched off top /center of structure at speed then its propelled out off edge of structure and now air born starts to drop to earth now that area of protective cover is in that scope of the rolling ball off top of stucture the canopy of protection . I tell the electrical engineers Black &vech that its a issue and we are not going by the NFPA . take care i just knew i should not have posted this but we call it the Rolling Ball Theory
- Location
- Illinois
- Occupation
- retired electrician
The standard does call for the use of the rolling sphere method, however it is not pushed off at a speed and propelled out from the edge. It is just placed on the building and its points of protection, and rolled around the structure, and anything under the sphere is considered to be protected. You can go to NFPA.org and look at section 4.7.3. It shows how the rolling sphere is to be used to determine the zones of protection. I can see a program like you speak of being used for this method, but just not as you have described it.
ohmhead
Senior Member
- Location
- ORLANDO FLA
Rolling ball program
Rolling ball program
Well yes we have seen the standard and know how it works but its outdated and old there is a new way to give the cover of protection now the rolling ball is a program simulated does the same thing just in a different way . I will ask at work to see how or why we are not following the NFPA ? How do we use a different method to get the same results and on a high profile project is this maybe a more stringent method of the known method in the NFPA or has time crept up on the regs ? Best to ya
Rolling ball program
Well yes we have seen the standard and know how it works but its outdated and old there is a new way to give the cover of protection now the rolling ball is a program simulated does the same thing just in a different way . I will ask at work to see how or why we are not following the NFPA ? How do we use a different method to get the same results and on a high profile project is this maybe a more stringent method of the known method in the NFPA or has time crept up on the regs ? Best to ya
joanie
Member
Rolling sphere method
According to NFPA 780-2008, the zone of protection is, "4.7.3.2* For structure heights exceeding 46m above earth or above a lower strike termination device, the zone of protection shall be the space in the vertical plane between the points of contact, and also under the sphere where the sphere is resting against a vertical surface of the structure and the lower strike termination device(s) or earth."
According to NFPA 780-2008, the zone of protection is, "4.7.3.2* For structure heights exceeding 46m above earth or above a lower strike termination device, the zone of protection shall be the space in the vertical plane between the points of contact, and also under the sphere where the sphere is resting against a vertical surface of the structure and the lower strike termination device(s) or earth."
i think this is the first ever lightning question in this forum. Just when i was going to demand it be changed to Lighting....
ohmhead
Senior Member
- Location
- ORLANDO FLA
Lighting strikes at gainsville
Lighting strikes at gainsville
Well it was never a subject one would have much to say or could really teach as they still study its effects or what it is and why .
There is a place in gainsville florida its the capital of lighting strikes its been said to have more strikes then any place on earth yearly ? I think florida has the highest record of strikes in the USA.
There is a grant project a kinda lighting research facility there they actually shoot rockets up into the clouds and the current passes thur a wire to earth and they record all data about lighting and its effects .
I always wondered how one would harness its power ?
I always thought tesla knew how to harness its great power or maybe be able to store its energy and use it .
Someone said once and i think it was Tesla ? That if you hung a wire up into the sky from ground earth and it ran back down to earth one big loop the magnetic field of the earth itself would induce a voltage in that wire and produce a small voltage ?
Think of it could we some how make or generate power from the sky everyone wants a new way to make or generate power our earth is a magnet with poles it turns na i must be crazy to think that ? Thinking about it i really think Tesla knew how ? comments take care
Lighting strikes at gainsville
Well it was never a subject one would have much to say or could really teach as they still study its effects or what it is and why .
There is a place in gainsville florida its the capital of lighting strikes its been said to have more strikes then any place on earth yearly ? I think florida has the highest record of strikes in the USA.
There is a grant project a kinda lighting research facility there they actually shoot rockets up into the clouds and the current passes thur a wire to earth and they record all data about lighting and its effects .
I always wondered how one would harness its power ?
I always thought tesla knew how to harness its great power or maybe be able to store its energy and use it .
Someone said once and i think it was Tesla ? That if you hung a wire up into the sky from ground earth and it ran back down to earth one big loop the magnetic field of the earth itself would induce a voltage in that wire and produce a small voltage ?
Think of it could we some how make or generate power from the sky everyone wants a new way to make or generate power our earth is a magnet with poles it turns na i must be crazy to think that ? Thinking about it i really think Tesla knew how ? comments take care
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