Learn More about Lightning Protection & Surge Protection
Common Questions from Architects:
Yes, in fact, more lightning protection systems are installed now than ever before. Today’s lightning protection systems are not very conspicuous and you don’t even see them unless you are looking for them. Buildings today are equipped with so many sensitive electronic systems that planners are tending to include lightning protection to help protect those systems and to keep those buildings up and running.
No. That is a very common misconception that dates back to Ben Franklin’s day. Lightning rods simply intercept a lightning strike and provide adequate paths to safely conduct the lightning to the ground. If lightning is zeroed in on a particular location, it will strike that location, whether there is lightning protection in place or not. It is helpful to remember that lightning travels several miles to reach the earth. Tiny objects on the ground have no influence on controlling the path lightning takes through the air.
In most cases unless you are looking for the lightning rods you can’t notice them. Lightning rods are just 12 inches tall and 3/8” in diameter. That’s not much bigger than a pencil. (Show sample?) That rod placed on a roof that is 30 –50 feet high and 18 inches in from the roof edge is hardly visible from ground.
There are also a number of things that can be done to make lightning protection less noticeable. There are different materials that can be chosen to blend with the architectural features, style and materials. For instance, tinplated copper can be chosen to blend with gray stonework or copper blends well with dark materials.
When designed during construction all of the lightning protection system, except the rooftop terminals, can be concealed and run inside the structure.
There are also ways to avoid the use of air terminals, such as substituting thick-walled metal railings for the lightning rods. There are also decorative finials that can be used as air terminals, making the lightning protection an architectural accent.
You need to intercept the lightning stroke and guide it to the steel frame. The structural steel of a building does conduct lightning, but you need a lightning protection system to provide the necessary interconnections to make sure that the lightning is able to pass harmlessly through the building. Without the lightning protection system, when a building is struck the lightning attempts to find a path to ground. If there are not enough interconnections providing a continuous path for the lightning to follow, there will be arcing or sideflashing. The lightning will also travel on other mechanical systems in a building such as the electrical or HVAC systems. The lightning current jumping from object to object within a building is dangerous and has been known to cause fires, explosions, etc.
There are satellites that monitor lightning activity all over the world. This activity is charted and provides statistics that tell just how often lightning strikes any given area. At any given moment there are 2000 thunderstorms happening somewhere in the world. The earth experiences 100 lightning flashes per second. The US alone has more than 40 million lightning strikes each year. Any given square mile in the US can expect approximately 40 strikes per year.
Some statistics regarding lightning damage include:
Between 1992 – 1996, it is estimated by that 1.7 billion dollars were paid out by insurance companies in lightning related commercial claims.
The Insurance Information Institute reports that approximately 5% of all commercial claims are lightning related.
In 1996 a Federal judge upheld a judgment levied by OSHA against a Pennsylvania firm for failure to provide adequate lightning protection, after two workers were killed by a lightning caused explosion.
The US Fire Administration reported in 2002 that it estimates 17,400 structural fires are caused by lightning each year. Dollar losses per lightning fire are nearly twice that of fires started by other means.
Any structure is a good candidate for lightning protection. All buildings are subject to lightning damage. Lightning protection should be offered to all clients. If owners don’t want to buy lightning protection, we suggest that you document their refusal to protect yourself down the road. The NFPA 780 Risk Assessment guide is a useful tool.
The need for lightning protection is being recognized more and more. Certainly, it is commonplace for lightning protection systems to be installed on schools, hospitals, health care facilities, airports, shopping centers, office buildings, manufacturing facilities, etc. In some parts of the country there has been a move to mandate the installation of lightning protection on certain types of buildings. For example, in Florida, lightning protection systems are required for installation on schools and health care facilities. Correctional facilities are also required to have lightning protection systems.
Typically, a small fraction of 1 percent of the value of the structure. Costs are lower when the system is designed and installed during construction. Retrofitting a system, is very common, but tends to be more expensive. In comparison with other building systems, such as security or plumbing, the lightning protection is much less costly.
Lightning protection does not fall under the expertise of most electricians. Lightning rods have their own NFPA standard that is separate from the National Electric Code that electricians are trained on. Lightning protection work should be performed by a specialty contractor who works as a sub to the electrical contractor. Lightning Protection works full-time on lightning protection; they are specialists, who are listed with UL, certified by the LPI and familiar with the NFPA and UL requirements for lightning protection.
Nothing can prevent lightning from striking. If lightning is zeroed in on a particular object it will strike that object regardless of anything that is on the ground. The purpose of lightning protection is to intercept the lightning strike and carry it to ground. This is accomplished by placing the rods at regular intervals on all of the highest and most exposed parts of a structure. These rods become the most likely point for the lightning streamer to attach, since they represent the shortest path to ground.
There are a number of good reasons to stay away from those types of systems. They do not comply with any US safety standards. They have actually been reviewed and rejected by the NFPA, NASA, various federal agencies, the University of Florida, New Mexico Tech and the International Conference on Lightning Protection scientific committee which is comprised of two dozen university affiliated lightning experts. The systems do not enjoy any independent support from the scientific community. There have been dozens of papers written by respected scientists, which explain why these systems cannot possibly perform as claimed.
These systems lack the support of the independent scientific community. There is no evidence that brushes or umbrellas can drain the charge out of a thunderstorm as claimed. Many times these brushes are incorporated into a system than is designed according to standards and simply substitute brush terminals for regular slender rods. Lightning researchers have not found any advantage to this practice, so these systems are actually a waste of money. Since the brush terminals can cost $50-$200 a piece. Researchers who have studied these systems include, the Air Force, NASA, FAA, University of Florida, New Mexico Tech and the University of Arizona.
Some cables are inevitable, but if the system is designed early enough in the planning stage much of the system can be run under the roof, leaving just the air terminals exposed. The structural steel of a building can often be used in lieu of conductors. This also limits the number of roof conductors that you will see.
Yes. The NFPA has maintained a standard for lightning protection for 100 years. The standard is continually updated and edited to incorporate new findings. For example, in the next few years, we will find that sharp-tipped lightning rods have been replaced by blunt or round-tipped rods in NFPA requirements. This is the result of field research at New Mexico Tech that has proven that blunt tipped rods are always successful in capturing a lightning discharge in comparison to a sharp tipped rod. The NFPA’s standard is based on the same practices and principles as standards for lightning protection all over the world.
The FAA, NASA, Dept of Energy, and DoD typically do not build any structures without these systems. In fact, there was a federal report issued two years ago that reviewed the technical validity of lightning protection and concludes that lightning protection systems are critical to protecting our national infrastructure. The American Meteorological Society issued a similar paper in early 2003.
Architects should be offering lightning protection to their clients and making their clients aware that without lightning protection, their buildings are at risk. The NFPA 780 Risk Assessment guide is helpful for that. Architects can also review lightning protection plans to ensure that the aesthetics of the building are not compromised. For example, architects can recommend the use of railings in lieu of air terminals for a particular parapet wall or the use of tin-plated air terminals to blend with the color of the roof material.
Other things to be aware of when planning for lightning protection might be provisions for chases if conductors are to be run inside concrete walls and the use of compatible adhesives as recommended by roofing manufacturers.
Not always. There are different guidelines in different parts of the country. Some Federal agencies require lightning protection, other agencies have requirements that if lightning protection is to be installed it must comply with NFPA 780. For example, the VA requires a UL Master Label for all lightning protection installations. The Federal Bureau of Prisons requires lightning protection systems. In Florida, the State Building Code requires lightning protection for all hospitals and schools. The Florida requirements will expand in 2004 to also cover all health care facilities including, outpatient buildings and extended care homes.