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Lightning
Safety Procedures
Safe Locations when there is choice
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High Risk Workgroups Statistics tell us that there are some specific activities which regularly contribute to ongoing lightning statistics, and there are some specific workgroups, which it is obvious that these need to be considered more closely and should be considered higher risk activities. These groups will include, (but are not limited to): Linesman and Electrical workers who work with switchboards, and copper conductors Telephone and cabling installers Railway line installation and maintenance workers Construction workers Roof workers Vineyard and Orchard workers Geologists Surveyors Environmentalists Pipe-line installers and maintenance workers Telephonists Explosives crews Drilling crews Emergency Services Workers There are also many sporting and recreational activities which have been major contributors to lightning fatality and ongoing injury statistics: Soccer Golf Yachting Rugby Cricket Horseracing Motorcycle racing Camping Scouts In recent years, Australian Lightning Strike Statistics have included: Mine Manager Dump Truck Driver Mine Worker Road Train Driver Vineyard Workers Electrical Linesman Electrical Worker Fisherman Footballers Soccer Players Cricketers Golfers Rock Climbers Schoolchildren |
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What to do if the safest action is not possible If the thunderstorm is above you (flash-to-thunder time < 5 seconds) and you are not able to take the action suggested above , then all you can do is minimise the risk of being struck, or affected by the indirect effects of lightning. You should then try to: Seek a depressed area; avoid high places Keep away from large isolated trees; (however, some protection is afforded in a forest if care is taken not to touch or stand too close to any particular tree) If in a group, stand at least 3 metres apart If hopelessly isolated in an exposed area and your hair stands on end, this is indicative that the e- fields at ground level , are rising very fast, and that lightning is about to strike, therefore assume a crouched position with your feet together, or sit with your feet tucked in close to your body. How lightning injures and kills Direct strike - statistics show that death resulted in over 70 % of cases. Side flash - e.g. standing near a tree - this can be as serious as a direct strike. Contact potential - physical contact with struck object has similar consequences to direct strike. Step voltage - lightning impulse traveling through/on ground and may pass through one limb/part and out another. Injuries include burns and paralysis but these are usually temporary. Surge propagation - person close to or in contact with an electrical appliance or power /communication line. Serious injury is not common but a number of deaths have resulted from telephone usage. First Aid treatment Contrary to popular belief and urban mythology, there is no danger in touching a person who has been struck by lightning. First aid is required urgently and should be started without delay. Breathing can be restored using EAR and blood circulation by CPR. These procedures must be continued until breathing/circulation is restored, or it can be medically confirmed that the patient is dead. Lightning victims are sometimes thrown violently against an object, or are hit by flying fragments (e.g., a shattered tree), so first aid may have to include treatment for traumatic injury.
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The
30/30 Rule The 3030 Rule states that when you see lightning, count the time until you hear the associated thunder, and if this time delay is 30 seconds or less, go immediately to a safe location as described above. If you cannot see the lightning, just hearing the thunder means you are most likely to already be within striking range, and it is time to seek whatever appropriate shelter is available. After the storm conditions have apparently dissipated or moved on, wait a further 30 minutes, after hearing the last thunder before leaving the safe area location. Should thunder be heard within this period, recount from the last thunder heard. The 3030 Rule is best suited for existing thunderstorms moving into the area. However, it cannot predict or protect against a first lightning strike. Thunderstorms can develop overhead where there will be no prior notice that a storm is incoming. Be alert to changes in sky conditions portending thunderstorm development directly overhead. Larger outdoor activities, with longer evacuation times, may require a longer lead-time than implied by the 3030 Rule. When lightning threatens, go immediately to a safer location. Do not hesitate. The lightning casualty statistics are full of stories where persons who were just about to make it to safety, when they were struck. Even a few extra minutes lead time can be life saving. Some might discount the odds of the lightning risk as being greater than winning a lottery. Just remember there are plenty of lottery winners every week! |
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Detection
and Warning Technologies Lightning warning and detection systems fall into two categories: Those systems that warn of the conditions that precede a lightning discharge "A Lightning Warning System" Those that report on historic events, albeit only seconds old. "A Lightning Detector" Lightning Detectors include the following types: Radio Frequency RF Detectors These are typically handheld devices which measure the unique Radio Frequency bursts produced by active lightning, and measure the amplitudes of the associated waveforms, thereby can very accurately determine the approximate distances to remote active lightning, and in some instances can determine the direction of the threat, can alert to any detected approach towards the users location, the approach speed, as well as he estimated time of arrival and estimated to clear. These devices are very cost effective, but they do have limitations, that is they can only detect active lightning and they cannot provide any level of pre lightning warning. Optical Monitors Although highly dependent upon other conditions such as rainfall, fog and other visibility issues, these devices can provide warning as they detect the light changes from cloud-to- cloud and cloud to ground lightning. Typically they have a limited range of only about 15 to 20 Nautical miles from the users location. Optical detectors are also used quite successfully by NASA on satellite platforms for monitoring thunderstorms without the terrestrial visibility issues. These are not recommended for use in lightning safety and are more suited to meteorological use in statistical recording. Inferometers These are multi-station devices, which are far more costly than the RF type detectors. These devices measure lightning strike data more precisely, and then usually require a skilled operator. These systems record information after lightning has occurred where the data is manipulated and then trended. Organisations like NASA would operate this type of equipment in conjunction with more expensive local field mills. GPATS GPATS are an Australian company who operate a National Lightning Detection Network, which networks with many storm sensing antennae located across Australia. These Sensors provide live data back to a main computer, which processes the strike data in conjunction with information from other sensors where Lightning strike data is able to be triangulated, with a strike location accuracy of some 500 mtrs able to be given. This data is archived and can be retrieved at a later date. This data is available live and is available by subscription. Lightning strike data can also be retrieved for a fee where organizations are looking for forensic analysis of lightning events. Lightning Warning Systems comprise the following types: Atmospheric Field Mill Monitors These devices measure the potential gradient (voltage) changes of the earth's negative electric field and report any changes as ambient thresholds build to avalanche and breakdown. These are quite expensive compared to the aforementioned lightning detectors, and are typically used in Aerospace, Munitions manufacture, Rocket Triggered Lightning Research activities as well as Golfing, Spaceport, munitions and defence applications. This is a predictive type of system that provides forewarning that conditions are becoming unstable and highly charged. Corona Point The Corona Point Discharge Sensor operates when it is exposed within an electrostatic field, and as an electrostatic field increases, the rate of discharge increases exponentially as a function of field strength. Current flow is the result which can be used by proprietary electronics of the LWS, to sense the presence of conditions which preceed and occur during lightning activity. The LWS sensor requires a sharp needle to create point discharge, which is also dependent on the electrostatic potential. Corona point has been used in conjunction with vibrating reed as well as RF detection to create a hybrid system which uses multiple monitoring methods. It is a proven and effective tool that monitors the local ambient conditions, and measures the static electro magnetic fields over an area. This level of measurable information enables a decision to be made prior to the onset of an electrical storm developing over a local area, as opposed to alerting after lightning has already occurred. |
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Lightning
Safety for Outdoor Workers Lightning safety awareness should be a priority at every outdoor facility and operation, where education is the single most important means to achieving this goal. The number one rule is that workers need to always consider their own situational safety, and those who may find themselves exposed to the risk should always recognize and anticipate their exposure to a changing or high-risk situation, and where appropriate move to a lower-risk location. The following steps are suggested: 1. Regularly monitor weather conditions and local weather forecasts prior to scheduled activities. 2. Suspension and resumption of work activities should be planned in advance, in conjunction with a Lightning Risk Policy 3. Understanding of SAFE shelters is essential. SAFE evacuation sites include: Fully enclosed metal vehicles with windows up Substantial buildings Low ground 4. UNSAFE SHELTER AREAS include all outdoor metal objects, like power poles, fences and gates, high mast light poles, electrical equipment, mowing and road machinery. AVOID solitary trees. AVOID water. AVOID open fields. AVOID high ground and caves. 5. If you feel your hair standing on end, and/or hear "crackling noises," you are in lightning's electric field. If caught outside during close lightning activity, immediately remove metal objects (including baseball cap, jewellery, belts, car keys etc), place your feet together, duck your head, and crouch down low with hands on knees. 6. Wait a minimum of 30 minutes from the last observed lightning or thunder before resuming activities. Be extra cautious during this phase as the storm may not be over. 7. People who have been struck by lightning do not carry an electrical charge and are safe to handle. Apply first aid immediately if you are qualified to do so. Get emergency help promptly. 8. Lightning's remote distance is easy to calculate: If you hear thunder, the associated lightning is within audible range 9. Suspend activities, allowing sufficient time to get to shelter. Of course, different distances to safety will determine different times to suspend activities. 10. Be aware of your surroundings and the nearest safe area. |
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