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Protecting Against Lightning Strikes andTheir Secondary Effects

By Jermone Kerr

Lightning: those dramatic bursts of white-hot voltage from the heavensthat can instantly incinerate trees, ignite fires, and knock out powerand communications lines. Each year, lightning causes massivedamage to business facilities across America. The destructive power oflightning is so great that even structures equipped with traditionallightning rods can suffer extensive damage.Strikes on petroleum industry facilities demonstrate the tremendousdestructive power of lightning activity and its aftereffects. Millions ofdollars of petrochemical products and facilities are destroyedworldwide each year by lightning and related phenomenon, and livesare often lost as a result of being in close proximity when these

facilities ignite or explode. For example, in the Nigerian fire of 1990, a670,000 barrel tank of light crude was set on fire by lightning,destroying the tank and its contents.Even if the facility is not directly struck by lightning, secondary effectssuch as bound charge and electromagnetic pulses can fry sensitivecircuitry in the vicinity. Failures may be catastrophic or a momentaryor long-term lockup, requiring replacement, repair, reprogramming, orrebooting.The danger of a lightning strike is exacerbated by so-called'prevention' devices such as lightning rods and early streameremitters, which are designed to collect and channel the force of a

strike to ground. This 200-year old technology was never intended forprotection of modern high-tech automated facilities, but rather barnsand other wood structures of that era.These devices actually bring millions of volts and thousands of ampsinto close proximity to sensitive electronics systems and flammableproducts. Companies promoting such devices choose to ignore theunderlying problems or the physics involved in protectingcontemporary systems. No matter what claims are made about suchdevices, using them only increases the risk of lightning-relateddamage.What exactly causes the terrifying yet fascinating phenomenon of

lightning? And more importantly, what can be done to prevent it fromdamaging your business and data?Let's start with the source. An electrical storm contains clouds calledthunderheads - electrically-charged bodies suspended in theatmosphere. The air serves as an insulator, separating the electricalcharge of the cloud from the ground or other clouds. These chargescontinue to build during the storm, inducing a similar charge ofopposite polarity onto the earth. The earth charge is concentrated at

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the surface just under the cloud and is roughly the same size andshape as the cloud, establishing a strong electrical field between thecloud and ground.As the storm intensifies, charge separation continues within the clouduntil the air between the cloud and earth can no longer act as an

insulator and a strike occurs. Charge neutralization (the 'strike') iscaused by the flow of electrons from the cloud to the earth such thatthere is no charge difference between the two bodies. The process issimilar to shorting out the terminals of a battery.When structures sit between the earth and the clouds, they arelikewise charged. Since they short out a portion of the separating airspace, they can trigger a strike.The lightning strike hazard for a given facility depends on a number offactors, including the facility's location, size, and shape. Thecharacteristics of a structure -- its height, shape, size and orientation --influences the hazard. Taller structures tend to collect strikes from

storm clouds in adjacent areas and trigger additional strikes as well. Inmountainous areas, even lower structures will trigger lightning.The larger the structure size, the greater the hazard of lightningexposure. For example, longer power transmission lines attract morestrikes. A 50-mile stretch of transmission line in central Florida couldexpect as many as 1,500 strikes per year.Given the random and destructive nature of lightning strikes, how canbusinesses protect their valuable facilities and electronic equipment -and the lives of their employees? The answer lies not in channelinglightning, but in preventing the charge from accumulating in the firstplace.

One technology, the Dissipation Array System (DAS), is being touted asthe ultimate solution for lightning protection. DAS is based on a naturalphenomenon known to scientists for centuries as the pointdischarge principle or charge transfer. A sharp point in a strongelectrostatic field will leak off electrons by ionizing the adjacent airmolecules, providing the point's potential is raised 10,000 volts abovethat of its surroundings. This principle is demonstrated by whatscientists call natural dissipation. The ionization produced by trees,grass, towers, fences, and other structures can naturally dissipate upto 90% of the total energy generated by a storm, thereby preventingthe formation of lightning.

The DAS employs the point discharge principle by providing thousandsof points with specific point separation which simultaneously produceions over a large area, thus preventing the formation of a streamer,which is the precursor of a lightning strike.This ionization process creates a flow of current from the point(s) intothe surrounding air. Under storm conditions, this ionization currentincreases exponentially with the storms electrostatic field, which can

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reach levels as high as 30,000 volts per meter of elevation above earthduring a mature storm.The charge induced on the site by the storm is removed from theprotected area and transferred to the air molecules. These chargedmolecules then move away from the site.

Thus DAS prevents strikes by continually lowering the voltagedifferential between the ground and the charged cloud to well belowthe lightning potential, even in the midst of a worse-case storm. Thisdifferential has been measured at up to 6,000 percent.Because it prevents rather than redirects lightning, DAS is possibly thebest long-term solution to lightning strike problems. One company,Lightning Eliminators and Consultants, Inc. (LEC), based in Boulder,Colorado, has long been at the forefront of DAS development. In thethree decades since LEC introduced DAS into the U.S. marketplace, ithas been the only lightning protection system proven to preventlightning strikes to any protected facility. The system has accumulated

over 20,000 system-years of history with a 99.7 per cent reliability.Thousands of Dissipation Array Systems have been installed to dateworldwide, in applications ranging from communications towers to tankfarms, electrical power lines to public buildings. DAS has been used toprotect facilities as large as three square kilometers and structures ashigh as 1,700 ft.Summarizing the benefits, DAS is:- Simple: The design is straightforward, reliable, and effective.- Passive: Consumes no power; it is activated by the energy of thestorm itself.- Universal: DAS can be used to protect any kind of building, tower,

power line, or large complex plant. Basic system concepts are custom-engineered for each individual facility, specially designed to accountfor size, height, area storm patterns, altitude, and other factors.- Preventative: Completely eliminates lightning strikes and all relatedsecondary effects from the protected area. Avoids problems inherent inlightning rod systems, which attract energy and attempt to conduct itto ground.The National Fire Protection Association, 780 committee is currentlyexamining the DAS technology because current lightning rod standardswere recently shown to have no basis in physics, to determine howDAS can be incorporated into their fire protection standards.

Jermone Kerr is with Lightning Eliminators and Consultants.

Q. What exactly does Lightning Eliminators do?

A. LEC engineers and installs lightning prevention systems to eliminate the direct lightningstrike and associated secondary effects. Our basic product is called the Dissipation ArraySystem. The technology used to do this is called "charge transfer technology". We provide anengineered systems' integrated approach for Fortune 500 clients worldwide. If you wish to

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understand more about this technology see the technical papers in our digital Library. Whileour main concern is our clients' lightning protection, we are also on the cutting edge ofscientific studies in the field of atmospheric science, as it relates to lightning.

Q. How long has LEC been doing this kind of work?

A. LEC has been researching lightning and engineering and installing systems since 1971.

Q. How long will a DAS system last?

A. An LEC Dissipation Array System (DAS) is made of stainless steel with galvanizedsupports, and has a service life of over 20 years under normal conditions. As a matter of fact,some systems are still functioning that were the first installation prototypes made in 1971. It'sour client's responsibility to advise us of the existence of corrosive environments in closeproximity to the DAS system; we will then fabricate the components of special materials forextended service life. Additionally, LEC offers optional re-certification or full maintenanceprograms for installed systems on a yearly schedule, allowing the systems' useful life toextend far beyond 20 years, reducing costs still further over the life of the system. It is alsothe client's responsibility to advise LEC of perceived problems once a system is installed someasures may be taken by LEC to rectify any issues during the warranty period.

Q. Have any DAS systems ever been hit by lightning?

A. Yes. What might cause a system to be struck? Detached cables, cut ground wires, nomaintenance performed for many years, damage by wind, rain, tornados, or incompleteoriginal engineering data from the site, new equipment surrounding the site, changes made tothe site, etc. With over 3000 systems installed, strikes account for less than 0.5 percent todate, a remarkable record. To allow for such possibilities we always issue a no-strike warrantyfor each system installed, and have been doing this for over 30 years. If we are informed bythe client of problems at a site, steps are immediately taken to find the root cause andupgrade the system as needed, at our expense within the warranty period.

Q. Can DAS meet NFPA-780?

A. Yes! The DAS can be designed to integrate with NFPA-780 systems. The DAS howeverperforms far above rods or other concepts. Don't be mislead with others performance claims.The DAS is a proven system with thousands of users worldwide in every industry. LEC alsoprovidesSBT and SBI components as part of UL Master label, NFPA 780 systems, should ourclients desire it.

NOTE: The current NFPA-780 standard actually has a disclaimer attached to it, absolving theNFPA from any legal ramifications because of applying the so-called standard. What thismeans is "you're on your own".

Q. Is a DAS system safe?

A. Yes it is. Think about this, strikes that hit your lightning rod or mini-brush system bringalong with them 30,000 to over 350,000 amps, as well as high di/dt producing severesecondary effects. Rods are totally missed from 20% to 40% of the time, that is lightningrod's performance. The DAS does not allow strike-enticing upward or counter leaders to form,thus, no strikes to the protected area. Should a leader come directly at a Dissipation ArraySystem, the leaders' tip energy is dissipated and delayed as it approaches the array, longenough to stop a direct strike from developing. Far safer than inviting 30,000 to 350,000Amps into or near your building and delicate electronics. If a DAS should fail, it always "failssafe" by the collection process.

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Q. Are LEC staff members engineers?

A. Yes, many of LEC's sales and management team members are degreed electrical andmechanical engineering professionals, including E.E., PhD, P. E.'s. All DAS projects passthrough tight engineering scrutiny prior to production, installation and commissioning.

Q. Just exactly how does a DAS save me money?

A. The DAS has the unique ability to discharge the site continually, eliminating direct strikesand the associated secondary effects. Many facilities managers normally considermaintenance costs for repairs, due to storm activity, as "normal" not knowing that most, up to85%, can be eliminated. The cost of equipment replacement is spread across all departments,along with labor and down time. Our clients continually tell us that they have experienced upto 85% reduction in electrical and electronic maintenance, and that's just in replacementparts.

Q. Why do some "me too" manufacturers claim they have equal or betterperformance in brush type layouts?

A. Some manufacturers do claim they have Dissipation Array systems, calling it a "generic"term, even though it is a fully protected and clearly copyrighted name.

Some also say they have more points in mini-brushes attached to lightning rods. Whilebrushes do some dissipation, they quickly fall into the saturation or upward/counter leadermode, as tests have shown. Once this happens, your chances of being struck rise significantly.The mini-brushes are no match for the 30,000 to 350,000 amps that may strike and vaporizethem. What you'll have left after such an event is a very expensive lightning rod system -minus the mini-brushes. It should be noted that brush components are actually UL listed aslightning rods, not dissipators. When buying such systems one should consider thereplacement costs.

The critical issue is not the number of points, its the spacing between points, and thearrangement of arrays based on engineering data from the site that provides no-strike

performance. Even if basic testing were done by the manufacturers of these so-called brushsystems, it would reveal the distance between points makes a huge difference inperformance. LEC long ago rejected this "brush," approach as unacceptable for protecting ourclients' facilities. When looking at others components, ask the lightning rod salesman, "What isthe discharge capability factor for your products? Are you providing a written workmanshipand performance warranty?

The DAS's specially engineered points, separated by specific distances, optimized andupgraded over the years for correct discharge, allows no buildup of strong attractive streamersor counter leaders. This careful approach is based on studies done in Japan, Russia and at ourU.S. based technology development center for over 30 years. In addition, each DAS design iscarefully engineered for each site, and comes with our guarantee of performance. If lightningstrike protection performance is critical to your facilities' operations, then choose a DASsystem.