IEC/TR 62713 Edition 1 0 2013 04 TECHNICAL REPORT RAPPORT TECHNIQUE Safety procedures for reduction of risk outside a structure Procédures de sécurité pour la réduction des risques à l’extérieur d’une[.]
Introductory remark
Lightning delivers extremely high instantaneous power, impacting objects for mere milliseconds This phenomenon can generate high voltages and currents reaching up to 200 kA As a result, thin wires may melt, and objects can heat to the point where flammable materials ignite or explode.
Lightning can cause explosive reactions when it strikes structures with trapped moisture, such as damp walls, joists, roofs, or trees Objects hit by lightning are at risk of exploding or igniting.
Lightning currents can penetrate into buildings and structures, along telecommunication lines and power lines, destroying electrical and electronic equipments
Figure 1 – Examples of roofs and facades damaged by lightning
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Lightning damage to human beings
General
In open spaces, people are susceptible to direct strikes (more likely when they are standing up), to side flashes, induced discharges, touch voltages and step voltages.
Direct strikes
A direct lightning strike poses the greatest danger among lightning threats, as the lightning current can pass through a person, leading to severe consequences such as unconsciousness, burns (both internal and external), apnoea, cardiac arrest, or paralysis.
Side flash
Staying under an isolated tree or near a mast poses significant dangers, as being within several meters of the trunk can lead to a side flash affecting the head or shoulder.
To ensure safety during storms, it is crucial to avoid seeking shelter in unprotected structures, particularly small, isolated buildings like huts and barns Additionally, structures featuring metallic roofs and non-metallic supports can pose a risk of electrical discharge.
Figure 4 – Unsuitability of metallic structures when not earthed
Touch or contact voltages
Metallic structures pose risks from both arcing caused by induced voltages and touch or contact voltages To minimize the risk of electrical shock from touch voltages, it is recommended to avoid potential lightning current conductors during storms Touch voltages occur when individuals standing on conductive ground make contact with a conductive structure that may have a different electrical potential due to a lightning strike.
Figure 5 – Electrization by touch voltage
Step voltages
When lightning strikes the ground, it disperses its current through the soil layers, causing a significant rise in potential at the strike point This results in step voltage, which can be hazardous In cases where lightning hits buildings, structures, or trees, the current travels into the ground via earthing devices or tree roots, creating dangerously high ground potentials Consequently, individuals near these structures may experience harmful step voltages.
People can experience step voltage when standing with their feet apart or when walking (see
Lightning strikes pose a significant hazard, particularly when they occur nearby The risk increases with higher ground resistivity, a shorter distance to the strike point, and a greater distance between a person's feet.
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Figure 6 – Current flow through body due to by step voltage
5 Effects of lightning strikes to human beings
Possible injuries
When a human being is directly struck by lightning, the voltage climbs up to about 300 kV
Lightning currents ranging from 100 kV to 500 kV primarily travel along the surface of the body rather than through it This phenomenon is why many individuals have survived direct lightning strikes.
The physiological effects can vary significantly, ranging from temporary dizziness to immediate cardiac arrest Individuals may experience neurological issues, visual impairments such as cataracts, hearing loss or ruptured eardrums, and paralysis Additionally, some may suffer from temporary fainting, which can include brief respiratory arrest, as well as comas that may last for varying durations.
The electrical current traversing the body from the feet to the head can cause severe or potentially fatal injuries, as the human body acts like a gel with an internal resistance of approximately 300 Ω.
Ionized skin and wet clothing create a pathway for electrical discharge, allowing lightning to travel along the body rather than through it This phenomenon can cause clothing to tear due to the intense pressure wave generated during the discharge.
Shoes can be propelled over long distances due to thermal shock, which is brief enough to cause only superficial burns However, metallic items like necklaces can attain high temperatures, resulting in more severe burns beneath the surface.
Burns can be classified as superficial, often resulting from electrical discharges that create linear or spread-out injuries However, burns caused by hot metallic objects tend to be more severe.
Lightning victims can also have erythemateous tree-like discharges or Lichtenberg figures
The pathognomonic figures, initiated by a leader circulating between clothes and skin, indicate the presence of a current flow These figures do not blanch under pressure and typically fade within one to two days Additionally, the lightning current can cause hair to burn.
Figure 7 – Lichtenberg figures on human skin [1] 1
A lightning strike can lead to sudden loss of consciousness, potential incontinence, and cessation of heart action and breathing, making the victim appear clinically dead This can result in cardiorespiratory arrest, necessitating immediate medical attention Additionally, various arrhythmias, including tachycardia, bradycardia, and ventricular fibrillation, may occur Brain injuries are also common, manifesting as amnesia, papillary abnormalities, painful paresthesiae, aphasia, and headaches.
Latent injuries may also occur only after some days or even months These include chronic pains, high blood pressure, memory failures and even personality changes
Injuries can manifest in various forms, including burns such as flash burns and contact burns from metal, as well as cardiac issues like cardiac arrest and hypertension Brain injuries may lead to central nervous system failures and personality changes, while respiratory complications can result in respiratory arrest and bronchospasm The musculoskeletal system may suffer from contusions, fractures, and chronic pain, and eye injuries can include corneal flash burns and retinal detachment Additionally, ear injuries may cause barotrauma and ruptured tympanic membranes, potentially leading to deafness.
How injured people can be helped
Call the emergency services immediately and obtain medical help First aid can be life- saving The emergency treatment shall be appropriate to the level of injury
Lightning injuries are categorized into three levels of severity: mild, moderate, and severe Individuals with mild injuries typically experience only a stunning effect from the lightning strike.
1 References in square brackets refer to the bibliography
When dealing with an individual who is awake but confused and experiencing amnesia, it's important to assess the situation carefully Recovery may take time, and the person might report symptoms such as paraesthesia and muscular pain that can persist for several months Providing supportive and physical care is crucial, and it is advisable to encourage the individual to seek transportation to a hospital for proper evaluation and treatment.
Moderately injured patients may experience disorientation and keraunoparalysis in their extremities for several hours, along with common symptoms such as hypotension, tympanic membrane injury, and first- to second-degree burns While survival is likely, these individuals may face permanent effects, including sleep disorders, personality changes, and challenges with certain mental functions In cases where the victim is not breathing, immediate cardiopulmonary resuscitation is crucial.
After contacting emergency services, assess the victim's breathing If an automated external defibrillator (AED) is accessible, it can be utilized Position the victim on their back, then open the airway by pressing the forehead back with one hand and lifting the jaw with two fingers of the other hand If the victim is not breathing or breathing abnormally, initiate resuscitation by pressing down on the breastbone with both hands, one over the other, while keeping your arms straight.
Perform 30 chest compressions in 20 seconds, depressing the breastbone by 5 cm each time Recheck the airway, pinch the victim's nostrils with two fingers, seal your lips over theirs, and deliver two rescue breaths to make the chest rise Continue the "30 compressions – 2 breaths" cycle until normal breathing is restored or professional help arrives For children aged 1 year to puberty, administer five initial rescue breaths before starting CPR as you would for an adult For infants under one year, follow specific guidelines for resuscitation.
1 year), procedures are somewhat different from those for a child
Severely injured victims frequently suffer from cardiac arrest, which can manifest as either ventricular standstill or fibrillation Successful cardiac resuscitation is possible, but direct brain damage is a significant risk, with blunt trauma, skull fractures, and intracranial injuries being prevalent Without the prompt intervention of a medical response team, the chances of recovery are typically low.
6 How to act in the presence of a thunderstorm
How to detect a lightning risk
Advanced lightning prediction and monitoring are accessible through local weather forecasts and various online platforms that offer near real-time lightning location data Lightning warning systems are essential for both industrial operations and personal safety, utilizing networks of detectors in certain countries to provide alerts via internet, fax, phone, email, or dedicated communication lines These systems enable the cessation of hazardous activities, safe transfers to shelters, and avoidance of exposure during lightning events While portable sensors are available for outdoor enthusiasts, they tend to be less reliable than fixed sensors, which, despite being bulkier, offer greater reliability and early warning capabilities Fixed sensors are suitable for industrial sites, golf courses, and camping areas, with a typical warning time of under 30 minutes, making it crucial to have safe shelters readily available on-site.
To assess the risk of a thunderstorm for outdoor activities, observe the approaching thunderclouds and listen for thunder You can estimate the storm's distance by counting the seconds between the flash and the thunder; divide this number by 3 to get the distance in kilometers If the storm is within 5 km, it is advisable to suspend outdoor sports events and steer clear of hazardous areas, such as isolated trees.
Half an hour after the last flash you see or the thunder you hear, you can assume that the lightning risk is over
Correct behaviour considerably reduces the risk of being injured by lightning Lightning is unpredictable; don’t trust your good luck!
Where to find safe locations
For optimal safety during a lightning storm, seek refuge in a building with lightning protection systems If your home lacks such protection, ensure all doors and windows are closed to block air currents, stay clear of fireplaces and chimneys, and refrain from using water if your structure has metallic plumbing.
Avoid open spaces such as balconies
During a thunderstorm, avoid using corded phones and refrain from calling from any landline Stay away from electrical power lines, telecommunication lines, and metallic pipes, including those for water and gas, as well as metallic chimneys and household electrical appliances like dishwashers and electric heaters Additionally, do not take a shower or bath while a thunderstorm is occurring.
To ensure safety during a storm, remain in the center of a room or open-sided building with your feet together and in a squatting position, especially in small barns or huts without lightning protection It is advisable to install surge protective devices (SPDs) in the incoming panelboard to safeguard electrical devices, televisions, antennas, and telecommunication cables, even if they are underground Each power and telecommunication line should have an SPD at its entry; if this is not possible, unplug those devices to prevent damage.
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Figure 9 – How to avoid strikes inside a house
What to do outdoors
While tall structures such as trees and masts are more likely to be struck by lightning, it's important to remember that lightning can hit any location Therefore, when thunderstorms are imminent, it's essential to follow the precautions outlined below.
To ensure safety during thunderstorms, it is crucial to avoid mountain climbing, walking near rivers, and swimming Additionally, refrain from horse riding and using bicycles, motorcycles, convertible cars, or any open vehicles, as well as tractors or harvesters, since these activities can increase the risk of being struck by lightning.
Don’t use sailing boats (unless properly protected against lightning), tents, open picnic pavilions, trams with open windows
In the countryside, it is crucial to quickly move away from high points and avoid staying in groups In urban areas, seek shelter in a store or public building for protection Maintain a safe distance from street lights, towers, metallic fences, and isolated trees, as these can pose risks While metallic street lights and towers may offer some protection against direct strikes, they can also create hazardous step voltages It is advisable to keep at least 1 meter, preferably 3 meters, away from any metallic street light or tower.
Don’t use umbrellas or golf clubs or hold long metallic or other conducting objects in your hands
Figure 10 – Avoid the highest point in this area
Isolated trees are particularly hazardous A safety distance of 10 m should be kept from the trunk and from the tree branches (see Figure 11)
Figure 11 – Safety distance (10 m) under a tree
The optimal outdoor position is not standing upright but rather crouching down, keeping the head close to the ground and arms wrapped around the legs Standing with feet together makes individuals vulnerable to direct strikes.
It is also dangerous to stay at the edge of a forest; in this case, it is better to stay inside the woods in the middle of the trees
Keep away from fences and other metallic structures, ditches and other wet places, open fields, hilltops and shores
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If you are absolutely obliged to move in a thunderstorm, take short steps or run (in which case only one foot touches the ground), avoiding unfolding any protruding metallic object
You should stay at least 1 m and preferably 3 m from walls, supports, metal fences, particularly from parts of the lightning protection system
To prevent a potential surface voltage gradient, individuals should stand with their feet together When in a group, it is important to maintain a distance of at least 1 meter, ideally 3 meters, without any physical contact between individuals.
Hazardous situation in a car
A metallic car constitutes good protection (Faraday-like shield) if windows are wound up As a good electrical conductor, a car keeps the passengers protected against lightning (see Figure
12) Nevertheless, it is advisable to drive carefully (at a moderate speed) in a thunderstorm
Vehicles with fibreglass bodywork (e.g mobile homes) as well as convertibles without roof metallic framework or roll bar offer a far lower protection
Figure 12 – Generally, a car acts as a Faraday cage
Dangers associated with driving a car in a thunderstorm include:
– the vehicle can be damaged through the tyres due to the transfer of heat and puncturing caused by the lightning current; tyres have no protecting effect;
– metallic parts should not be touched while sitting in the car as they may obtain a high voltage;
– electronics can be perturbed by the electromagnetic field accompanying the lightning current (check the functionality of the car electronics after a thunderstorm!);
– bright flashes and simultaneous loud thunder may cause fatal driving errors and heavy rain obstructs the view;
– traffic lights and signals may not be working properly
You should delay your journey for the duration of an intense thunderstorm.
What to do when camping
In a camping tent or trailer, be sure that a metallic conductor surrounding the whole volume to be protected is correctly earthed
Caravans and mobile homes with an outer metallic skin offer the same safe protection as cars with metallic bodywork However, persons inside vehicles with fibreglass bodywork are endangered
– never put up tents or position vehicles or their trailers used as living accommodation in prominent sites, on hilltops, at the edge of the forest or under isolated trees;
– stay at least 3 m from neighbouring tents and camping cars;
– don’t install metallic wires between tents and camping cars
– where a protected structure or metallic skin vehicle is not available, stay inside the tent in the crouching down position, keeping distance from metallic tent poles;
– unplug all cables from site supply points;
– remove or take down external antennas;
– don’t forget that metallic feet, connected to the bodywork of mobile homes generally act as lightning conductors.
Thunderstorms in mountainous regions
Lightning poses a significant threat to hikers and mountaineers in mountainous areas due to rapidly changing weather conditions It is crucial to quickly and safely move away from peaks, ridges, cliffs, and trees when storms are approaching or if you notice your hair standing on end To minimize risk, remove metallic items like jewelry and watches, and crouch down to reduce your body's surface area and protect against electrical currents.
Don’t touch a rock face with hands or feet; a lightning current could flow through your body and throw you several metres away
When a thunderstorm is imminent, cease your ascent and seek refuge in a safe mountain hut equipped with a lightning protection system, or stay in valley accommodations until the storm passes.
Metal bivouac boxes provide protection on fixed rope routes, while caves under ledges or lower rock faces also offer relative safety When using these shelters, maintain a distance of 1 meter from the wall for added security.
Metallic ropes, wet climbing ropes, ladders and bars as well as damp rock faces should not be touched
Thunderstorms can initiate rock falls and dangerous avalanches.
What to do on water
As a thunderstorm approaches, it is crucial to leave the water and seek shelter in a protected area If you find yourself offshore in a watercraft, cease all activities and move below deck if possible To minimize risk, squat with your legs closed and avoid contact with the rigging or any metallic components Remember that lightning can spread its current over large areas, remaining hazardous even 100 meters from the strike point A sailing boat equipped with a lightning protection system can enhance safety during such storms.
Scuba divers should exercise caution due to the risks associated with lightning While the likelihood of a direct lightning strike underwater is minimal, lightning can vaporize water, creating a shockwave that may cause serious injuries, including ruptured eardrums, embolisms, and loss of consciousness The danger increases significantly when divers exit the water.
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Figure 13 – Example of a lightning protection system on a sailing boat
What to do at open air festivals
Open air events follow the same basic safety rules as other outdoor activities Spectators on open platforms are at risk during thunderstorms and should seek shelter in lightning-protected areas Platforms that have a lightning protection system or are covered with metal or reinforced concrete roofs are considered safe zones.
No metallic parts, columns, walls, crowd barriers should be touched Keep at least 1 m and preferably 3 m away from all these and other conductive parts
You should place your feet close together to avoid a possible surface voltage gradient
Before any event with many spectators attending, a good weather forecast should be obtained.
What to do when playing outdoor sports
For outdoor sports participants, it is crucial to prioritize safety by seeking shelter at the first indication of lightning or thunder Coaches and officials must halt games or practices immediately upon hearing thunder or seeing lightning Players and coaches should take refuge in buildings equipped with lightning protection systems or inside closed metal vehicles Activities can only resume 30 minutes after the last thunder is heard or lightning flash is observed.
If protected structures or closed vehicles are not available, the following areas should be considered as the second-best possibility:
– buildings without lightning protection systems;
To minimize surface voltage gradients, it is essential to maintain a distance of at least 1 meter, preferably 3 meters, from buildings or metallic masts Additionally, keeping feet close together can further reduce these gradients.
Golf courses pose significant risks during thunderstorms due to their open landscapes and the presence of isolated trees Injuries and fatalities from lightning strikes often happen when golfers attempt to continue playing as storms approach or seek refuge under solitary trees or at the periphery of tree clusters.
Trees should never be considered trees as protected zones and standing in groups should be avoided; keeping a distance of at least 5 m from one another is highly recommended
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[1] ANDREWS, C.J., COOPER, M.A., DARVENIZA, M., MACKERRAS, D., Lightning
Injuries: Electrical, Medical, and Legal Aspects, CRC Press, Boca Raton, USA, 1992
[2] BARTHOLOME C.W.: Cutaneous manifestations of lightning injury, Arch Dermatology,
[3] BOUQUEGNEAU, C., Doit-on craindre la foudre?, EDP Sciences, les Ulis (Paris),
[4] BOUQUEGNEAU, C and RAKOV, V., How dangerous is lightning?, Dover
[5] COORAY, V., editor, Lightning Protection, IET Power and Energy Series 58, London,
[6] COST P18 (The Physics of Lightning Flash and its Effects), Lightning Safety Brochure,
[7] GOURBIÈRE, E et GARY, C., Secours aux foudroyés – Recommandations,
[8] Society of Atmospheric Electricity of Japan, Lightning Threat! What can I do? Safety
[9] VDE/ABB, Wie kann man sich gegen Blitzeinwirkungen schützen?, Electrosuisse,
4.2 Dommages aux personnes causés par la foudre 29
4.2.4 Foudroiement par tensions de toucher ou de contact 31
4.2.5 Foudroiement par tensions de pas 31
5 Effets des coups de foudres sur le corps humain 32
5.2 Comment aider une personne foudroyée 34
6 Conduite à tenir en cas d’orage 35
6.1 Comment détecter un risque d’orage 35
6.2 Comment trouver des emplacements sûrs 35
6.4 Situation dangereuse à l’intérieur d’un véhicule 38
6.8 Conduite à tenir dans les festivals en plein air 41
6.9 Conduite à tenir lors d’activités sportives à l’extérieur 41
Figure 1 – Exemples de toits et de faỗades endommagộs par la foudre 29
Figure 2 – Coup de foudre direct 29
Figure 3 – Foudroiement par éclair latéral 30
Figure 4 – Inadéquation des structures métalliques non reliées à la terre 30
Figure 5 – Electrisation par tension de toucher 31
Figure 6 – Diffusion du courant au travers du corps due à la tension de pas 32
Figure 7 – Figures de Lichtenberg sur la peau d’une personne [1] 33
Figure 8 – Réanimation cardio-pulmonaire (RCP) 34
Figure 9 – Comment éviter la foudre à l’intérieur d’une maison 36
Figure 10 – Eviter le point le plus élevé de cette zone 37
Figure 11 – Distance de sécurité (10 m) sous un arbre 38
Figure 12 – En général, une voiture se comporte comme une cage de Faraday 39
Figure 13 – Exemple de système de protection contre la foudre sur un voilier 41
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PROCÉDURES DE SÉCURITÉ POUR LA RÉDUCTION DES RISQUES À L’EXTÉRIEUR D’UNE STRUCTURE
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La CEI/TR 62713, qui est un rapport technique, a été établie par le comité d’études 81 de la
CEI: Protection contre la foudre
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