An example of a standard, pointed-tip air terminal

A lightning rod (or lightning protector) (USA) or "lightning conductor" (UK), is a metal strip or rod, usually of copper or similar conductive material, a lightning safety measure designed to protect tall or isolated structures (such as the roof of a building or the mast of a vessel) from lightning damage. Its formal name is lightning finial or air terminal. Sometimes, the system is referred to as a lightning discharger; however, this term is more often used to refer to lightning protection systems in general or specific components within them. The United States Patent Office labels "Lightning protectors" in Class 174 (Electricity: conductors and insulators), Subclass 2 (Lightning protectors) and Subclass 3 (Rods). Image File history File links Pointed_Lightning_Rod. ... Image File history File links Pointed_Lightning_Rod. ... For the Wikipedia policy regarding controversial issues in articles, see Wikipedia:Guidelines for controversial articles. ... Jalaluddin Mansur Nuriddin born in Brooklyn, New York, 1944, is one of the founding members of The Last Poets, a group of poets and musicians that evolved in the 1960s out of the Harlem Writers Workshop in New York City. ... This article is about metallic materials. ... For other uses, see Copper (disambiguation). ... In science and engineering, conductors are materials that contain movable charges of electricity. ... Lightning is a highly visible form of energy transfer. ... Not to be confused with lighting. ... The United States Patent and Trademark Office (PTO or USPTO) is an agency in the United States Department of Commerce that provides patent and trademark protection to inventors and businesses for their inventions and corporate and product identification. ...

History

Lightning damage has been with humanity since people started building structures. Early structures made of wood and stone tended to be short and in valleys and as a result lightning hit rarely. As buildings became taller, lightning became a significant threat. Lightning can damage structures made of most materials (masonry, wood, concrete and even steel) as the huge currents involved can heat materials, and especially water to high temperatures causing fire, loss of strength and explosions from superheated steam and air. A steam explosion (also called a littoral explosion, or fuel-coolant interaction, FCI) is a violent boiling or flashing of water into steam, occurring when water is either superheated, or rapidly heated by fine hot debris produced within it. ...

Europe

Wooden church with lightning rods and grounding cables

The church tower of many European cities, usually the highest structure, was the building often hit by lightning. Early on, Christian churches tried to prevent the occurrence of the damaging effects of lightning by prayers. Priests prayed, Image File history File links Download high-resolution version (1232x1840, 591 KB) Bielsko-Biała, Poland. ... Image File history File links Download high-resolution version (1232x1840, 591 KB) Bielsko-Biała, Poland. ...

temper the destruction of hail and cyclones and the force of tempests and lightning; check hostile thunders and great winds; and cast down the spirits of storms and the powers of the air.

Peter Ahlwardts ("Reasonable and Theological Considerations about Thunder and Lightning", 1745) advised individuals seeking cover from lightning to go anywhere except in or around a church.^[1]

United States

In the United States, the pointed lightning rod conductor, and more accurately the "lightning attractor", was invented by Benjamin Franklin as part of his groundbreaking explorations of electricity. Franklin speculated that, with an iron rod sharpened to a point at the end, Benjamin Franklin (January 17 [O.S. January 6] 1706 – April 17, 1790) was one of the most well known Founding Fathers of the United States. ... Electricity (from New Latin ēlectricus, amberlike) is a general term for a variety of phenomena resulting from the presence and flow of electric charge. ... For other uses, see Iron (disambiguation). ...

the electrical fire would, I think, be drawn out of a cloud silently, before it could come near enough to strike [...].

Franklin had speculated about lightning rods for several years before his reported kite experiment. This experiment, in fact, took place because he was tired of waiting for Christ Church in Philadelphia to be completed so he could place a lightning rod on top of it. There was some resistance from churches who felt that it was defying divine will to install these rods. Franklin countered that there is no religious objection to roofs on buildings to resist precipitation, so lightning, which he proved to be simply a giant electrical spark, should be no different. As an act of philanthropy, Franklin decided against patenting the invention. The Anglicans of the Church of England founded Philadelphias Christ Church in 1695 and built a small wooden church on the site by the next year. ... For other uses, see Philadelphia (disambiguation) and Philly. ... For other uses, see Patent (disambiguation). ...

In the 19th century the lightning rod became a symbol of American ingenuity and a decorative motif. Lightning rods were often embellished with ornamental glass balls^[2] (now prized by collectors) that also served to provide visual sign of a lightning strike (when the rod is struck the glass ball shatters and falls off, indicating to the owner which rod got struck and that they should check it and the grounding wire for damage). The ornamental appeal of these glass balls has also been incorporated into weather vanes. Alternative meaning: Nineteenth Century (periodical) (18th century — 19th century — 20th century — more centuries) As a means of recording the passage of time, the 19th century was that century which lasted from 1801-1900 in the sense of the Gregorian calendar. ... This article is about the material. ... Weather vane Weather cock Aerovane A weather vane, also called a wind vane, is a movable device attached to an elevated object such as a roof for showing the direction of the wind. ...

Balls of solid glass were occasionally used in a method purported to prevent lightning strikes to ships. It is worth noting here not because it worked, which it didn't, but because it reveals a lot about pre-scientific thought. The basic principle was that glass objects, being non-conductors, are seldom struck by lightning. Therefore, goes the theory, there must be something about glass that repels lightning. Hence the best method for preventing a lightning strike to a wooden ship was to bury a small solid glass ball in the tip of the highest mast. The random behavior of lightning ensured that the method gained a good bit of credence even after the development of the marine lightning rod soon after Franklin's initial work.

Nikola Tesla's U.S. Patent 1,266,175  was an improvement in lightning protectors. The patent was granted due to a fault in Franklin's original theory of operation; the pointed lightning rod actually ionizes the air around itself, rendering the air conductive, which in turn raises the probability of a strike. Many years after receiving his patent, in 1919 Dr. Tesla wrote an article for The Electrical Experimenter entitled "Famous Scientific Illusions", in which he explains the logic of Franklin's pointed lightning rod and discloses his improved method and apparatus. Nikola Tesla (1856-1943)[1] was a world-renowned Serbian inventor, physicist, mechanical engineer and electrical engineer. ... Logic (from Classical Greek λόγος logos; meaning word, thought, idea, argument, account, reason, or principle) is the study of the principles and criteria of valid inference and demonstration. ...

Some of DuPont Explosives manufacturing sites, which were surrounded by pine trees, used various lightning protection devices. During the 1950s, DuPont was making nitroglycerin in some buildings and moving it in 'Angel Buggies' to the packing building. Employees at those sites were very sensitive to potential lightning strikes.^{[citation needed]}

In the 1990s, the 'lightning points' were replaced as originally constructed when the statue of Freedom atop the United States Capitol building in Washington was restored.^{[citation needed]} The statue was designed with multiple devices which are tipped with platinum. The original aluminum cap of the Washington Monument was also equipped with multiple lightning points,^{[citation needed]} and the rays that radiate from the crown of the Statue of Liberty in New York Harbor constitute a lightning-dissipation device. ^{[citation needed]}

Structure protectors

Landscape suited for purpose of explanation: (1) Represents Lord Kelvin's "reduced" area of the region^[3]; (2) Surface concentric with the Earth such that the quantities stored over it and under it are equal; (3) Building on a site of excessive electrostatic charge density; (4) Building on a site of low electrostatic charge density. (Image via U.S. Patent 1,266,175 .)

Image File history File links Size of this preview: 800 × 236 pixelsFull resolution (1952 × 575 pixel, file size: 42 KB, MIME type: image/png) This image concerns the landscape concerning the explanation of lightning protectors. ... Image File history File links Size of this preview: 800 × 236 pixelsFull resolution (1952 × 575 pixel, file size: 42 KB, MIME type: image/png) This image concerns the landscape concerning the explanation of lightning protectors. ... William Thomson, Archbishop of York, has the same name as this man. ... This article is about Earth as a planet. ... Electrostatics is the branch of physics that deals with the force exerted by a static (i. ... Charge density is the amount of electric charge per unit volume. ...

Lightning diversion

Conventional lightning rods are connected via a low-resistance wire or cable to the earth or water below, where the charge may be safely dissipated. The diversion theory states that the lightning rod protects a structure purely because it is grounded, and thus a lightning strike that happens to attach to the protector will be diverted around the structure and "earthed" through a grounding cable or conductor.^[4] There is some uncertainty as to why a lightning strike might preferentially attach to a lightning protector; the leading assumption is that the air near the protector becomes ionized and thus conductive due to the intense electric field. Various manufacturers make these claims. Electrical resistance is a measure of the degree to which an electrical component opposes the passage of current. ...

Lightning Arresters

In telegraphy and telephony a lightning arrester is placed where wires enter a structure, preventing damage to electronic instruments within and ensuring the safety of individuals near them. Lightning arresters, also called surge protectors,are devices which are connected between each electrical conductor in a power and communications systems and the earth. These provide a short circuit to the ground that is interrupted by a non-conductor over which lightning jumps. Its purpose is to limit the rise in voltage when a communications or power line is struck by lightning. Telegraph and Telegram redirect here. ... In telecommunication, Telephony encompasses the general use of equipment to provide voice communication over distances. ... Surge and noise protector Most hV6 A surge protector is an appliance designed to protect electrical devices from power surges and voltage spikes. ... For alternate meanings see Short circuit (disambiguation) A short circuit (sometimes known as simply a short) is a fault whereby electricity moves through a circuit in an unintended path, usually due to a connection forming where none was expected. ... It has been suggested that Ground conductor be merged into this article or section. ... In science and engineering, conductors are materials that contain movable charges of electricity. ...

The non-conducting material may consist of a semi-conducting material like silicon carbide or zinc oxide, or a spark gap. Primitive varieties of such spark gaps are simply open to the air, but more modern varieties are filled with dry gas and provided with a small amount of radioactive material to encourage the gas to ionize when the voltage across the gap reaches a specified level. Other designs of lightning arresters use a glow-discharge tube (essentially like a neon glow lamp) connected between the protected conductor and ground, or any one of a myriad of voltage-activated solid-state switches called varistors or MOV's. Lightning arresters built for substation use are impressive devices, consisting of a porcelain tube several feet in length and several inches in diameter, filled with disks of zinc oxide. A safety port is supplied on the side of the device to vent the occasional internal explosion without shattering the porcelain cylinder. A 385-volt metal oxide varistor A varistor is an electronic component with a significant non-ohmic current-voltage characteristic. ... MOV may refer to MOV (x86 instruction) Metal oxide varistor (an electronic component) .mov (QuickTimes file format) The Mid-Ohio Valley Motor Operated Valve Measurable Organizational Value This page concerning a three-letter acronym or abbreviation is a disambiguation page—a list of articles associated with the same title. ...

Electric power system lightning protection

High-tension power lines carry a lighter conductor (sometimes called a 'pilot') wire over the main power conductors. This conductor is grounded at various points along the link, or else insulated from the tower structures by small insulators which are easily jumped by lightning voltages. This latter scheme allows the pilot wire to be used for communications purposes, or to carry current for aircraft clearance lights. Electrical substations may have a web of grounded wires covering the whole plant. “Pylon” redirects here. ...

Lightning protection of mast radiators

Mast radiators insulated against ground have always a gap at their basement. When lightning hits it, it jumps there over. A small inductivity in the feeding line between the mast and the tuning unit ( usually 1 windings) reduces voltage increase and protects so the transmitter from dangerous voltages. The transmitter has to be equipped with a device monitoring the electric properties of the antenna. This is very important, as a discharge may still remain after lightning strike and damage the gap or the insulators. The monitoring device switches off the transmitter when the antenna shows uncorrect behaviour, e.g. as a result of undesired discharge. When transmitter is switched off, these discharge go away. The monitoring device makes several attempts of reswitch. If after all reswitches the antenna shows improper behaviour, e.g. as result of structural damage, the transmitter remains switched off. A typical mast radiator Base feed: mast is fed from Aerial Tuning Unit on right via conductor to top of brown ceramic insulator. ...

Lightning conductors and grounding precautions

Ideally, the underground part of the assembly should reside in an area of high ground conductivity. If the underground cable will resist corrosion well, it may be covered in salt to improve its electrical connection with the ground. While the electrical resistance of the lightning conductor between the air terminal and the earth is of concern, the inductive reactance of the conductor may be of even more importance. For this reason, the route of the downconductor is kept short, and any curves are made with a large radius. If these measures are not observed, lightning current may arc over any such obstruction, resistive or reactive, which it encounters in the conductor. The arc current will at the very least damage the lightning conductor, and can easily find another conductive path and cause fires or other disasters. For the hazard, see corrosive. ... For other uses, see Salt (disambiguation). ...

Extent of protection of a lightning rod

Considerable material is used in the construction of lightning protection systems, so it is prudent to work out where a rod structure will have the greatest effect. Historical understanding of lightning, from statements made by Ben Franklin^[5], assumed that each device protected a cone of 45 degrees ^[6]. This has been found to be unsatisfactory for protecting taller structures, as it is possible for lightning to strike the side of a building. A better technique to determine the effect of a new arrester is called the rolling sphere technique and was developed by Dr Tibor Horváth. To understand this requires knowledge of how lightning 'moves'. As the step leader of a lightning bolt jumps toward the ground, it steps toward the grounded objects nearest its path. The maximum distance that each step may travel is called the critical distance and is proportional to the electrical current. Objects are likely to be struck if they are nearer to the leader than this critical distance. It is standard practice to approximate the sphere's radius as 60 m near the ground. This article is about the geometric object, for other uses see Cone. ... A step leader is a path of ionization air which extends downward from a thundercloud during the initial stages of atmospheric breakdown during a lightning strike. ... It has been suggested that Ground conductor be merged into this article or section. ...

Electricity travels along the path of least resistance, so an object outside the critical distance is unlikely to be struck by the leader if there is a grounded object within the critical distance. Noting this, locations that are safe from lightning can be determined by imagining a leader's potential paths as a sphere that travels from the cloud to the ground. For lightning protection it suffices to consider all possible spheres as they touch potential strike points. To determine which strike points consider a sphere rolling over the terrain. At each point we are simulating a potential leader position and where the sphere touches the ground the lightning is most likely to strike. Points which the sphere cannot roll across and touch are safest from lightning. Lightning protector should be placed where they will prevent the sphere from touching a structure. A weak point in most lightning diversion systems is in transporting the captured discharge from the lightning rod to the ground, though.^[7] For other uses, see Sphere (disambiguation). ...

Should a lightning rod have a point?

This was a controversy as early as the 1700's. In the midst of political confrontation between Britain and its American colonies, British scientists maintained that a lightning rod should have a ball on its end. American scientists maintained that there should be a point. The controversy has not been completely resolved, mostly due to the fact that proper controlled experiments are nearly impossible in such work; in spite of the work of Moore, et al[described below] most lightning rods seen on buildings have sharp points.

Nikola Tesla's
"Lightning-Protector"
U.S. Patent 1,266,175 ; An early type of dissipater-arrester, which the patent states to prevent and safely dissipate lightning strikes

It is commonly believed, erroneously, that a protector ending in a sharp point at the peak is the best means to conduct the current of a lightning strike to the ground. According to field research, a rod with a rounded or spherical end is better. "Lightning Rod Improvement Studies" ^[8] by Moore et al say: Lightning-Protector US1266175 patent File links The following pages link to this file: Lightning rod Categories: Images with unknown source ... Lightning-Protector US1266175 patent File links The following pages link to this file: Lightning rod Categories: Images with unknown source ... Nikola Tesla (1856-1943)[1] was a world-renowned Serbian inventor, physicist, mechanical engineer and electrical engineer. ... In electricity, current refers to electric current, which is the flow of electric charge. ...

Calculations of the relative strengths of the electric fields above similarly exposed sharp and blunt rods show that although the fields, prior to any emissions, are much stronger at the tip of a sharp rod, they decrease more rapidly with distance. As a result, at a few centimeters above the tip of a 20-mm-diameter blunt rod, the strength of the field is greater than that over an otherwise similar, sharper rod at the same height. Since the field strength at the tip of a sharpened rod tends to be limited by the easy formation of ions in the surrounding air, the field strengths over blunt rods can be much stronger than those at distances greater than 1 cm over sharper ones.

The results of this study suggest that moderately blunt metal rods (with tip height–to–tip radius of curvature ratios of about 680:1) are better lightning strike receptors than are sharper rods or very blunt ones.

In addition, the height of the lightning protector relative to the structure to be protected and the Earth itself will also have an effect.^[9][10] In physics, the space surrounding an electric charge or in the presence of a time-varying magnetic field has a property called an electric field. ...

Lightning dissipation

Lightning dissipaters (known as Early Streamer Emission, Dissipation Array Systems, and Charge Transfer Systems) claim to make a structure less attractive to lightning and other charges which can flow through the Earth's atmosphere around it. These generally encompass systems and equipment for the preventative protection of objects located on the surface of the earth from the effects of atmospherics. The devices deal with the phenomena such as electrostatic fields, electromagnetic fields, field transients, static charges, and any other related atmospheric electricity phenomena. This article does not cite any references or sources. ... Air redirects here. ... Cloud to ground Lightning in the global atmospheric electrical circuit. ... A phenomenon (plural: phenomena) is an observable event, especially something special (literally something that can be seen from the Greek word phainomenon = observable). ... In physics, an electric field or E-field is an effect produced by an electric charge that exerts a force on charged objects in its vicinity. ... The electromagnetic field is a physical field that is produced by electrically charged objects and which affects the behaviour of charged objects in the vicinity of the field. ... Transient means passing with time. ... Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interactions. ... Cloud to ground Lightning in the global atmospheric electrical circuit. ...

The most common individual dissipator rods (or dissipator elements) appear as slightly-blunted metal spikes sticking out in all directions from a metal conductor.^[11] These elements are mounted on short metal arms at the very top of a radio antenna or tower, the area by far most likely to be struck. The dissipation theory states an alteration in the potential difference (voltage) between the structure and the storm cloud, miles above, theoretically reduces, but not eliminates, the risk of lightning strikes.^[12] Various manufacturers make these claims. Induced upward lightning strokes occurring on tall structures (effective heights of 300 m or more) can be reduced by altering the shape of the structure.^[13] A yagi antenna Most simply, an antenna is an electronic component designed to send or receive radio waves. ... Masts of the Rugby VLF transmitter in England Radio masts and towers are, typically, tall structures designed to support antennas (also known as aerials in the UK) for telecommunications and broadcasting, including television. ... International safety symbol Caution, risk of electric shock (ISO 3864), colloquially known as high voltage symbol. ... For other uses, see Cloud (disambiguation). ...

Evaluations and analysis

A controversy regarding the assortment of operation theories dates back to the 1700s, when Franklin himself stated that his lightning protectors protected buildings by dissipating electric charge. He later retracted the statement with a disclaimer stating that the exact mode of operation of the device was something of a mystery at that point. Thus began a 250-year dispute between the dissipation theory and the diversion theory of lightning protection. The dissipation theory states that a lightning strike to a structure can be prevented by altering the electrical potential between the structure and the thundercloud by transferring electric charge (such as from the nearby earth to the sky or vice versa).^[14][12] Transferring electric charge from the nearby earth to the sky is done by erecting some sort of tower equipped with one or more sharply-pointed protectors upon the structure. It is noted that sharply-pointed objects will indeed transfer charge to the surrounding atmosphere^[15][16] and that a considerable electric current through the tower can be measured when thunderclouds are overhead. It is worth considering that these dissipators and arrestors have been around for a long time (see the history section above) and that there is also no direct proof that the dissipation theory is incorrect. A reading of the scientific literature on the subject will reveal much of the problem. It has been regarded as impossible to conduct a controlled experiment with voltages approaching natural lightning.^[17] Also, test structures that are equipped with lightning instrumentation may languish for years without a strike, and then be subjected to a strike that destroys the instrumentation. For the Wikipedia policy regarding controversial issues in articles, see Wikipedia:Guidelines for controversial articles. ... In mathematics, a direct proof is a way of showing the truth or falsehood of a given statement by a straightforward combination of established facts, usually existing lemmas and theorems, without making any further assumptions. ...

Lightning strikes to a metallic structure can vary from leaving no evidence excepting perhaps a small pit in the metal to the complete destruction of the structure. (Rakov, Page 364^[18]). When there is no evidence, attempts at making analysis of such strikes is difficult. This means that a strike on an un-instrumented structure must be visually confirmed, and the random behavior of lightning renders such observations difficult. Thus if we strip away the two centuries of legal actions, political activity and general outrage exhibited by both sides, we find that the current state of the dissipation/diversion controversy is a draw; that neither theory has or can be proven, and that essentially all data pertaining to the behavior of lightning on structures must be considered anecdotal. The research situation is improving somewhat, however.^{[19][18][20][21]} There are also inventors working on this problem,^[22][23] such as through a lightning rocket. While controlled experiments may be off in the future, very good data is being obtained through techniques which use radio receivers that watch for the characteristic electrical 'signature' of lightning strikes using fixed directional antennas.^{[24][25][26][27]} Through accurate timing and triangulation techniques, lightning strikes can be located with great precision, and so strikes on specific objects can often be confirmed with confidence. A lightning rocket consists of a rocket launcher that is in communication with a detection device that measures the presence of electrostatic and ionic change in close proximity to the rocket launcher that also fires the rocket launcher. ...

These ancient buildings on the Great Wall of China are protected by the modern grounded lightning mast between them.

The introduction of lightning protection systems into standards allowed various manufactures to develop protector systems to a multitude of specifications and there are various lightning rod standards.^{[28][29][30][31][32][33][34][35][36]} The NFPA's independent third party panel found that "the [Early Streamer Emission] lightning protection technology appears to be technically sound" and that there was an "adequate theoretical basis for the [Early Streamer Emission] air terminal concept and design from a physical viewpoint". (Bryan, 1999^[37]) The same panel also concluded that "the recommended [NFPA 780 standard] lightning protection system has never been scientifically or technically validated and the Franklin rod air terminals have not been validated in field tests under thunderstorm conditions." In response, the American Geophysical Union concluded that "[t]he Bryan Panel reviewed essentially none of the studies and literature on the effectiveness and scientific basis of traditional lightning protection systems and was erroneous in its conclusion that there was no basis for the Standard." AGU did not attempt to assess the effectiveness of any proposed modifications to traditional systems in its report. ^[38] Storehouse and barracks of Great Wall near Beijing. ... Storehouse and barracks of Great Wall near Beijing. ... The Great Wall of China (simplified Chinese: ; traditional Chinese: ; pinyin: ; literally Long wall) or (simplified Chinese: ; traditional Chinese: ; pinyin: ; literally The long wall of 10,000 Li (里)[1]) is a series of stone and earthen fortifications in China, built, rebuilt, and maintained between the 5th century BC and the 16th... The National Fire Protection Association (established 1896) is an independent, voluntary-membership, nonprofit (tax-exempt) organization. ...

No major standards body, such as the NFPA, UL, and the NLSI, has currently endorsed a device that can prevent or reduce lightning strikes. The NFPA Standards Council, following a request for a project to address Dissipation Array Systems and Charge Transfer Systems, denied the request to begin forming standards on such technology (though the Council did not foreclose on future standards development after reliable sources demonstrating the validity of the basic technology and science were submitted). ^[39] Members of the Scientific Committee of the International Conference on Lightning Protection has issued a joint statement stating their opposition to dissipater technology. ^[40] The UL Mark Underwriters Laboratories Inc. ...

Various investigators believe the natural downward lightning strokes to be unpreventable.^[13] Since most lightning protectors' ground potentials are elevated, the path distance from the source to the elevated ground point will be shorter, creating a stronger field (measured in volts per unit distance) and that structure will be more prone to ionization and breakdown.^[41] Scientists from the National Lightning Safety Institute claim that these dissipation devices are nothing more than expensive lightning protector and that they, unlike traditional methods, are not based on "scientifically proven and indisputable technical arguments". ^[42] William Rison of the National Lightning Safety Institute states that in his opinion the underlying theory of dissipation is "scientific nonsense".^[43] According to these sources, there is no proof that the dissipation arrangement is at all effective. According to opponents of the dissipation technology, the various designs of dissipaters indirectly "eliminate" lightning via the alteration of a building's shape and only have a small effect (either intended or not) because there is no significant reduction to the susceptibility of a structure to the generation of upward lightning strokes. ^[13] Some field investigations of dissipaters show that their performance is comparable to conventional terminals and possess no great enhancement of protection. According to these field studies, these devices have not shown that they totally eliminated lightning strikes. ^[44]

Aeroplane protectors

Lightning protection for aircraft is provided by mounting devices on the aircraft structure. The protectors are provided with extensions through the structure of the aircraft's outer surface and within a static discharger. Protection systems for use in aircraft must protect the electronic equipment which is critical to aircraft flight and equipment which is not critical to aircraft flight. Aircraft lightning protection provides an electrical path having a plurality of conductive segments, continuous or discontinuous, that upon exposure to a high voltage field form an ionization channel due to the system's breakdown voltage. Various lightning protection systems must reject the surge currents associated with the lightning strikes. Lightning protection means for aircraft include components which are dielectrics and metallic layers applied to the ordinarily lightning-accessible surfaces of composite structures. Various ground connection means to the layers comprises a section of wire mesh fusing the various layers to an attachment connecting the structure which to an adjacent ground structure. Composite-to-metal or composite-to-composite structural joints are protected by making the interface areas conductive for transfer of lightning current. Flying machine redirects here. ... This article does not cite any references or sources. ... An open surface with X-, Y-, and Z-contours shown. ... A portion of a static discharger showing a metal portion exposed. ... Electronic equipment is anything that is electronic, from your washing machine to a headphone or a modem. ... A hummingbird Female Mallard Duck in midflight A dragonfly in flight Flight is the process by which an object achieves sustained movement either through the air by aerodynamically generating lift or aerostatically using buoyancy, or movement beyond earths atmosphere, in the case of spaceflight. ... En [ [ ciencia ] ] y [ [ ingeniería ] ], los conductores son los materiales de los cuales contenga las cargas movibles [ [ electricidad ] ]. Cuando una diferencia potencial eléctrica se impresiona a través de puntos separados en un conductor, las cargas móviles dentro del conductor se fuerzan para moverse, y una corriente el... International safety symbol Caution, risk of electric shock (ISO 3864), colloquially known as high voltage symbol. ... The magnitude of an electric field surrounding two equally charged (repelling) particles. ... Ionization is the physical process of converting an atom or molecule into an ion by changing the difference between the number of protons and electrons. ... Breakdown Voltage (Insulator) = The minimum voltage that makes an insulator react as a conductor. ... A current of short duration that occurs when power is first applied to capacitive loads or temperature dependent resistive loads such as tungsten or molybdenum heaters-usually lasting no more than several cycles. ... This article is about metallic materials. ... Look up composite in Wiktionary, the free dictionary. ... A mesh is similar to fabric or a web in that it has many connected or weaved pieces. ... For other uses, see Joint (disambiguation). ...

Some aircraft lightning protection systems use a shielded cable system. These systems carry one or more conductors enclosed by a conductive shield having one end connected to grounding element to provide protection from electrostatic interference. Such systems reduce the electromagnetically induced voltage in a shielded conductor and provides protection from the induced electromagnetic interference of lightning. This network provides a high impedance and changing to a very-low impedance in response to a momentary voltage surge electromagnetically induced in the shield, thereby establishing a conductive circuit path between the shield and ground. Any surge voltage from lightning drives a shield current through the circuit to provide an electromagnetic field of the opposite direction canceling and reducing the magnitude of the overall electromagnetic field that links the shielded cable. Four-conductor shielded cable with metal foil shield and drain wire A shielded cable is a simple insulated cable with a braided shield of strands of copper(or other metal), a non braided(solid) shield, or a winding of metal tape completely enclosing this insulation. ... Electrostatics is the branch of physics that deals with the force exerted by a static (i. ... For other uses, see Interference (disambiguation). ... Electromagnetism is the physics of the electromagnetic field: a field, encompassing all of space, composed of the electric field and the magnetic field. ... Look up induction in Wiktionary, the free dictionary. ... In electrical engineering, Impedance is a measure of opposition to a sinusoidal electric current. ... The word ground has several meanings: The surface of the Earth Soil, a mixture of sand and organic material present on the surface of the Earth Ground (electricity), in electrical engineering, something that is connected to the Earth or at the voltage defined as zero (in the US, called ground...

Watercraft protectors

Lightning protection installations on watercrafts comprises a lightning protector mounted on the top of the mast or on the deck. Electrical conductors are attached to the device and run downward to a "grounding" conductor in contact with the water. The grounding conductor may be retractable, part of the hull, or attached to a centerboard. A watercraft is a vehicle designed to float on and move across (or through) water for pleasure, physical exercise (in the case of many small boats), transporting people and/or goods, or military missions. ... mizzen mast, mainmast and foremast Grand Turk The mast of a sailing ship is a tall vertical pole which supports the sails. ... A deck is a permanent covering over a compartment or a hull[1] of a ship. ... In science and engineering, conductors, such as copper or aluminum, are materials with atoms having loosely held valence electrons. ... It has been suggested that Ground conductor be merged into this article or section. ... The ground conductor is an electric conductorable rope on the top of pylons. ... A hull is the body or frame of a ship or boat. ... A centreboard is a form of removable keel on a small sailing boat or dinghy which can be removed to lower the draught (or depth) of the vessel. ...

See also

• List of lightning rod patents
• Václav Prokop Diviš (1698-1765), independently created lightning rod in Vienna during 1750-1754.
• James Otis, Jr., contemporary of Ben Franklin, killed at doorway by lightning in Andover, MA on May 23, 1783.

Below is a list of lightning rod patents (or lightning protector patents). ... Václav Prokop DiviÅ¡ (born 26 March 1698 in Helvíkovice – died 25 December 1765 in PřímÄ›tice) was a Czech theologian and natural scientist who invented the lightning rod between 1750 and 1754 independently of Benjamin Franklin, and constructed the first electrified musical instrument in history, the so... Events January 4 - Palace of Whitehall in London is destroyed by fire. ... Year 1765 (MDCCLXV) was a common year starting on Tuesday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Saturday of the 11-day slower Julian calendar). ... For other uses, see Vienna (disambiguation). ... Events March 2 - Small earthquake in London, England April 4 - Small earthquake in Warrington, England August 23 - Small earthquake in Spalding, England September 30 - Small earthquake in Northampton, England November 16 – Westminster Bridge officially opened Jonas Hanway is the first Englishman to use an umbrella James Gray reveals her sex... 1754 was a common year starting on Tuesday (see link for calendar). ... This article is about the political advocate of the emperpor of the galatic empire. ... Portrait of Benjamin Franklin Dr. Benjamin Franklin (January 17, 1706–April 17, 1790) was an American journalist, publisher, author, philanthropist, abolitionist, public servant, scientist, librarian, diplomat, and inventor. ... Andover is a town located in Essex County, Massachusetts. ... is the 143rd day of the year (144th in leap years) in the Gregorian calendar. ... 1783 was a common year starting on Wednesday (see link for calendar). ...

Notes

References

External links

• "Researchers find that blunt lightning rods work best". USA Today. (06/10/2002)
• Federal Aviation Administration, "FAA-STD-019d, Lightning and surge protection, grounding, bonding and shielding requirements for facilities and electronic equipment". National Transportation Library, 2002-08-09.
• Kithil, Richard, "Lightning Rods: Recent Investigations". National Lightning Safety Institute, September 26, 2005.
• Kithil, Richard, "Should Lightning Rods be Installed?". National Lightning Safety Institute, September 26, 2005.
• Kithil, Richard, "Fundamentals of Lightning Protection". National Lightning Safety Institute, September 26, 2005.
• Nailen, Richard L., "Lightning controversy goes on", The Electrical Apparatus, Feb 2001.
• Lightning Safety Alliance education page