Lightning Protection Systems


Use the following format to cite this article:

Lightning protection systems. (2014) Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://articles.extension.org/pages/71216/lightning-protection-systems. 

 

Lightning protection systems are recommended for all barns to reduce the risk of damage sustained from a lightning strike. Thunderstorms involving lightning occur across the United States but are most prevalent in central and eastern states. Lightning is a stream of pure energy, approximately 1/2- to 3/4-inch wide and surrounded by 4 inches of extremely hot air, that is looking for the path of least resistance between the clouds and the ground. The amperage from a lightning flash can be approximately 2,000 times greater than the current in a typical home.

Lightning and Potential Damage

The powerful force of lightning can ignite fires in buildings, damage electrical equipment, and electrocute humans and livestock. Typically, lightning enters a building by striking a metal object on the roof, directly striking the building, hitting a tree or structure (for example, a silo) that causes the strike to jump to a nearby building, or striking a power line or wire fence that provides a path into the structure. You can protect your farm or ranch structures by installing a lightning protection system, which will direct a strike away from your buildings and dissipate the strike in a safe manner.

Lightning Protection System Components

Barn Protection

(Source: Penn State Ag Safety & Health)

A lightning protection system consists of the following five parts: air terminals (lightning rods), conductors, ground connections (electrodes), bonding, and lightning arrestors.

Air terminals. Air terminals, or lightning rods, are metal rods or tubes installed at every projecting high point of a building—such as the peak, a dormer, a flagpole, or a water tank—to intercept a lightning bolt. Solid copper rods should be a minimum of 3/8-inch in diameter, and solid aluminum rods should be a minimum of 1/2-inch in diameter. Rods should extend between 10 and 36 inches above the projecting object. Typically, rods are 10 to 24 inches long; extra support or a brace is needed for a rod that is more than 24 inches long. The most effective spacing is 20 feet apart for rods that are less than 24 inches long or 25 feet apart for rods that are between 24 and 36 inches long. Additionally, a rod should be located within 24 inches of the end of any building ridge or projecting object. Strategic placement of rods on a structure ensures that lightning will strike the rods rather than another part of the building.

Conductors. Conductors, which are copper or aluminum cables, provide the connection between the air terminals and the earth to direct the lightning strike deep into the earth where it can safely dissipate. Choose copper or aluminum rather than a combination of the two because galvanic or chemically corrosive action can occur between the two elements. Main conductors connect all of the lightning rods with the down conductors and then connect to the ground connections.

Ground connections. Ground connections, or electrodes, provide contact with the ground to safely dissipate the lightning charge. A minimum of two ground connections should be used for most buildings; additional ones may be needed for larger structures. The type of ground connection may depend on the conductivity of the soil in your area. Ground electrodes should be 1/2-inch diameter, 10-foot long copper-clad steel or solid copper rods driven at least 8 feet into the ground.

Bonding. Bonding involves branch conductors that protect against sideflashes by connecting metal objects (such as ventilation fans, water pipes, and so on) with the grounding system. Common grounding can eliminate lightning sideflashes. Grounding is achieved when all electrical systems, telephone systems, and underground metal piping are connected to the lightning protection system.

Lightning arrestors. Lightning arrestors provide protection against a strike entering your building through the electrical wiring system and thereby causing potential power surges that may result in severe damage to electrical devices. To provide the best possible protection, lightning arrestors should be installed on the building’s exterior where the electrical service enters the building or at the interior service entrance. 

Protection of Livestock and Trees

Examine your farm or ranch with a certified installer to determine whether lightning protection should be extended to protect valuable trees; trees located within 10 feet of a structure, such as a silo; or trees used for shade by livestock. If livestock stand under a tree, they can be killed by a direct lightning strike to the tree or from contact with resultant charged soil. To avoid this scenario, consider removing trees favored by livestock, fencing livestock away from trees, or providing protection with a conductor system. 

Lightning protection for a tree involves placing air terminals at the tips of the main trunk and attaching a full-size grounding cable to a ground rod. The ground rod should be located away from the tree’s root system. Air terminals with smaller cables can be attached to main branches. If the tree is 3 feet in diameter or larger, use two ground rods attached to the main conductor system.

Protection of Fencing

Lightning can travel up to 2 miles along an ungrounded wire fence, posing a threat to humans and livestock. Fences may be attached to wooden posts, steel posts set in concrete or to buildings, and even trees (not recommended). In all circumstances, the fence should be grounded to safely route the lightning’s voltage into the earth. To ground a fence, drive 1/2-inch steel rods or 3/4-inch pipe 5 to 10 feet into the ground next to wooden fence posts at intervals of 150 feet. Allow a few inches of the ground rod or pipe to extend past the top of the adjacent fence post. Attach the rod or pipe to the fence post with pipe straps to ensure a tight connection.

System Installation and Maintenance

A certified installer should install your lightning protection system to reduce the risk of a system failure and to ensure that your system meets necessary codes and standards. The Lightning Protection Institute certifies systems meeting all its requirements. To maintain a system’s certification, regular maintenance and annual inspection must be completed. Damage due to high winds, building additions, and roof repairs or upgrades can alter a system’s performance. To locate a certified installer in your area, click one of the resource links below:

Lightning Protection Institute

Underwriters Laboratories

Resources

Click here for more information about structural lightning safety from the National Lightning Safety Institute.

Click the link below for more detailed information about the related topic.

Lightning Safety

 

Use the following format to cite this article:

Lightning protection systems. (2014) Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://articles.extension.org/pages/71216/lightning-protection-systems. 

 

Sources

 

Chamberlain, D. and Hallman, E. (1995) Lightning protection for farms. Cornell Cooperative Extension. Retrieved from http://ecommons.library.cornell.edu/bitstream/1813/5168/2/LIGHTNING%20PROTECTION%20FOR%20FARMS.pdf.

Linn, R. (1993) Lightning protection for the farm. Montguide. Montana State University. No longer available online.

Murphy, D. (1988) Lightning protection for the farm. The Pennsylvania State University. Retrieved from http://nasdonline.org/1168/d001010/lightning-protection-for-the-farm.html.

Specifications for lightning protection – ASAE engineering practice. (1998) The Disaster Handbook 1998 National Edition. University of Florida Institute of Food and Agricultural Services. No longer available online.

 

Reviewed and Summarized by:
Linda M. Fetzer, Pennsylvania State University – lmf8@psu.edu
William C. Harshman, Pennsylvania State University (Has since retired)
Tom Karsky, University of Idaho (Has since retired)
Dennis J. Murphy, Pennsylvania State University (Has since retired)
Aaron M. Yoder, University of Nebraska Medical Center – aaron.yoder@unmc.edu

Lightning Safety

Photo of storm clouds approaching

Photos provided by the Central States Center for Agricultural Safety and Health (CS-CASH)

 

Lightning and thunderstorms typically occur during the spring and summer months. As human beings, we are great conductors of lightning because approximately 65 percent of the human body consists of salt and water. Lightning can cause injury or death to humans and animals, either by direct strike or transmission indirectly to and through the body. Also, it can cause structure fires.

Cloud-to-ground lightning can cause injuries by direct or indirect means because the current can branch off to a person from a nearby tree, fence, or other tall object. Lightning flashes can send a current through the ground to a person after hitting a nearby object, such as a tree. Additionally, injuries or death can occur due to fires or falling objects caused by a lightning strike.

Awareness and Preparation

National Oceanic and Atmospheric Administration (NOAA) Weather Radio and local radio/television stations are the best sources for the latest forecasts and emergency updates in your area. Remember that a thunderstorm watch means that storms are possible whereas a thunderstorm warning means that severe weather has been reported by spotters or radar in your area. Even though it is not possible to have lightning without thunder, there are times when you cannot distinctively hear the thunder. When this happens, typically during the summer months, the lightning you see is called heat lightning. The term dry lightning refers to lightning that occurs without rain. This type of lightning can cause forest fires.

In preparation for thunder and lightning storms, you and your family should take the following actions:

  • Choose a place in the house where family members will meet in the event of a storm.
  • Make a list of specific items that need to be brought inside during a storm.
  • Keep trees and shrubbery trimmed and remove debris from around buildings to reduce the potential that items (for example, weak tree limbs) will become projectiles.
  • Ensure that you have a place where your animals can go to be protected.
  • Consider installing permanent shutters that can be closed easily and quickly for better protection.
  • Install lightning rods on your home, barn, and other structures that house animals. Also, install a lightning arrestor or diverter on any electric fence.

When and Where to Seek Shelter

The National Weather Service recommends using the 30/30 rule to know when to move to safety and when to return to your activities. If lightning is within six miles, locate a safe place and stay there until no lightning has been seen nor thunder heard for 30 minutes. The “flash to bang” count can determine the distance of the lightning. When you see lightning, start counting seconds (one one-thousand, two one-thousand, and so on) and stop when you hear the thunder. Every five seconds equals a mile, so move to safety if the count is less than 30 seconds.

Choose your safe place wisely. A fully enclosed metal vehicle or building is a safe shelter if the outer metal shield is not compromised. This means you should keep windows closed; avoid objects that penetrate from the outside to the inside; and in a vehicle, do not touch external objects such as door handles or radio knobs.  In a lightning storm, avoid water, high and open ground, metal spaces, canopies, picnic or rain shelters, trees, and electrical/electronic equipment. If you are in a structure that has curtains or blinds over windows, close them to prevent glass shards from flying into the structure from a broken window.

If you cannot find a safe shelter, place yourself as low as possible to the ground without lying on the ground. Seek low ground, such as a ditch, or crouch down with your feet together and your hands over your ears to protect your hearing.

During a lightning storm, take the following precautions:

  • Do not hold anything that can conduct electricity, such as a shovel, a hoe, or a golf club.
  • Do not operate farm equipment.
  • Avoid water! Do not take a bath or a shower or run water for any purpose (for example, to wash dishes). If you are swimming or boating, get out of the water.
  • Protect your electronics and electrical items from lightning strikes and power surges by unplugging televisions, computers, and other valuable appliances.
  • Avoid electric fences, clotheslines, metal pipes, rails, telephone poles, and other conductors.

Fires and Entrapments due to Lightning

An electrical fire can occur when an appliance or a tool catches on fire. If possible, unplug the appliance from the outlet; however, if doing so places you in danger, turn off the current at the fuse box. Use an ABC or BC fire extinguisher on an electrical fire, and remember never to pour water on an electrical fire. Leave the area, and contact your local fire department if the fire is more serious than a simple appliance fire. If you notice fallen electrical wires, report them immediately to the police or local utility company. If you find someone trapped in a vehicle by fallen wires, tell the person to stay in the vehicle without touching any metal parts of the car while you go for help.

Injury Types and First Aid

Most lightning strike victims survive, but common injuries include burns, broken bones, heart attacks, and neurological damage. Short-term effects of lightning strike include memory loss, chronic headaches, ringing in the ears, fatigue, personality changes, muscle spasms, joint stiffness, numbness, sleep difficulties, and dizziness. Additional injuries can be caused by fires or objects that fall after being struck by lightning.

First aid needs to be started immediately after a lightning strike. If the person is conscious, check his or her breathing and pulse. If there is no pulse, begin cardiopulmonary resuscitation (CPR). Check the victim for additional injuries, such as fractures, but do not move the person if you suspect a spinal injury. If the victim sustained an electrical burn, cover the burned area with a dry, sterile dressing. Remember to look for multiple burn areas because separate burned areas may exist where the current entered and exited the victim’s body. Also look for burned areas on the person’s extremities (fingers and toes) and on areas next to buckles or jewelry. Contact your local emergency responders. Even if a person does not appear to be injured, he or she still should be seen by a medical professional.

Resources

Click here for more information about personal lightning safety from the National Lightning Safety Institute.

Click here for more information about NOAA Weather Radio.

Click here for information about lightning safety for outdoor workers from the National Lightning Safety Institute.

Click the link below for more detailed information about the related topic.

Lightning Protection Systems

 

Sources

Cyr, D. and Johnson, S. (2003) Lightning safety. University of Maine Cooperative Extension. Retrieved from http://umaine.edu/publications/2315e/.

Kithil, R. (n.d.) Decision tree for personal lightning safety. National Lightning Safety Institute. Retrieved from http://www.lightningsafety.com/nlsi_pls/decision_tree_people.html.

Thunderstorm safety. (n.d.) American Red Cross. Retrieved from http://www.redcross.org/prepare/disaster/thunderstorm.

Thunderstorm safety checklist. (2009) American Red Cross. Retrieved from https://www.redcross.org/get-help/how-to-prepare-for-emergencies/types-o….

 
Reviewed and Summarized by:
Linda M. Fetzer, Pennsylvania State University – lmf8@psu.edu
William C. Harshman, Pennsylvania State University (Has since retired)
Tom Karsky, University of Idaho (Has since retired)
Dennis J. Murphy, Pennsylvania State University (Has since retired)
Aaron M. Yoder, University of Nebraska Medical Center – aaron.yoder@unmc.edu
 

Cold-Related Conditions and Agriculture

 

Winter Ranch Scene
Winter Scene

(Source: Wyoming AgrAbility)

Use the following format to cite this article:

Cold-related conditions and agriculture. (2012). Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://www.extension.org/pages/66813/cold-related-conditions-and-agriculture.

Farmers and ranchers complete tasks in all types of weather conditions. Extreme weather conditions put agricultural producers at risk for heat-related and cold-related illnesses and injuries. (Click here to view an article about heat-related illnesses) Individuals working in extremely cold or wet weather can experience such occupational health conditions as hypothermia, frostbite, trench foot, and chilblains.

The four environmental factors that cause cold-related illnesses are

  • low temperature,
  • strong and/or cool winds,
  • dampness, and
  • cold water.

The most dangerous factor in winter weather is wind chill, a measure of the rate at which skin exposed to the combined effects of wind and cold loses heat. When wind increases, the body loses heat at a faster rate, which causes body temperature to decrease.

Individuals generate body heat from food and through muscular activity and lose heat through convection, conduction, radiation, and sweating. In general, the processes of generating and losing body heat are balanced, resulting in a constant body temperature. When a person’s body temperature drops below the normal temperature of 98.6°F, he or she may experience blood vessel constriction and decreased peripheral blood flow, putting the person at risk for adverse cold-related conditions.

Cold-Related Conditions

Hypothermia

Hypothermia occurs when a person’s body is unable to produce heat and has used all its stored energy or is losing body heat faster than it can be produced. As a result, a person’s body temperature decreases. When a person’s body temperature drops below 95°F degrees, the heart, nervous system, and other organs can be adversely affected. The most common causes of hypothermia are exposure to cold weather and immersion in cold water.

Early Symptoms

  • Shivering
  • Decreased energy
  • Fatigue
  • Loss of coordination

Symptoms after Prolonged Exposure to Cold

  • Dilated pupils
  • Decreased pulse
  • Shallow breathing
  • Loss of consciousness

First Aid Response

  • Call 911 or emergency medical personnel.
  • Find a warm room or shelter and remove any wet clothing.
  • Drink a warm (nonalcoholic or caffeine-free) beverage if one is available.
  • Stay dry and warm by wrapping up in a blanket.
  • If you are assisting a person with hypothermia, and he or she does not have a pulse, begin cardio-pulmonary resuscitation (CPR). (Click here to be directed to the article “Basic CPR.”)

Frostbite

Frostbite occurs when skin tissue freezes and loses water, leading to the potential for cell damage. Skin can freeze at temperatures of 30°F and below, and wind chill can also cause frostbite. Fingers, toes, cheeks, nose, and ears are the areas of the body most typically affected by frostbite. Frostbitten skin may look white or grayish yellow and may feel cold, hard, and possibly waxy to the touch.

Symptoms

  • Numbness
  • Aching
  • Tingling
  • Stinging

First Aid Response

  • Find a warm room or shelter.
  • Avoid walking if your feet or toes are frostbitten.
  • Soak affected areas in warm (not hot) water.
  • Avoid rubbing the affected area because rubbing could cause tissue damage.
  • Wrap affected area in a soft cloth.
  • Do not use a heating pad, fireplace, or radiator for warming.
  • Do not warm the area if there is a risk of refreezing.

Trench Foot

Trench foot occurs when a person’s feet have prolonged exposure to cold (60°F or less) and wet conditions. This condition is similar to frostbite but is typically less severe.

Symptoms

  • Reddening of the skin
  • Numbness
  • Leg cramps
  • Swelling
  • Tingling pain
  • Blisters or ulcers
  • Bleeding under the skin
  • Gangrene

First Aid Response

  • Remove shoes or boots and wet socks.
  • Dry the feet.
  • Avoid walking to reduce the risk of damage to foot tissue.

Chilblains

Chilblains are painful inflammations in small blood vessels in the skin that result from exposure to cold temperatures. The areas most commonly subject to chilblains include the toes, fingers, ears, and nose.

Symptoms

  • Redness
  • Blistering
  • Itching
  • Inflammation
  • Ulceration (in severe cases)

First Aid Response

  • Avoid scratching the affected skin.
  • Slowly warm the skin.
  • Use corticosteroid creams to relieve itching and swelling.
  • Keep blisters and ulcers clean and covered.

Preventing Cold-Related Conditions

There are several actions you can take to maintain a normal body temperature in cold and/or wet weather.

Clothing

  • Wear a minimum of three layers of clothing: an outer layer that breaks the wind, a middle layer that retains insulation, and an inner layer that allows for ventilation.
  • Have a change of clothes readily available in case your garments become wet.
  • Always protect your head and face because you can lose up to 40% of your body heat through your head.
  • Protect your feet from cold and dampness by wearing layered socks inside comfortable, insulated footwear.
  • Protect your hands with insulated gloves (dexterity can be affected at temperatures below 59ºF).

Environment

  • Use on-site sources of heat, such as air jets and radiant heaters, to provide warmth.
  • Make sure that a heated shelter or vehicle is available for anyone who has experienced prolonged exposure to wind chill temperatures below 20°F.
  • Reduce drafty or windy areas within buildings to shield work areas.
  • If the temperature drops below 30°F, use thermal insulating material on the handles of your equipment.
  • Avoid sitting or kneeling on cold, unprotected surfaces.

Personal Safety

  • If you suffer from a medical condition such as diabetes, atherosclerosis, spinal cord injury, arthritis, and so on, you may need to take special precautions when working in cold environments because you could be especially susceptible to cold-related illness and injury.
  • If you take prescription medication (heart medication, sedatives, and so on), check with your physician to determine whether you need to take any special precautions when working in the cold.
  • Never use alcohol or drugs when working in a cold environment because such substances increase heat loss and can impair judgment.
  • Know the signs and symptoms of cold-induced conditions and how to respond appropriately with first aid.
  • Seek warm shelter if you experience symptoms (heavy shivering, severe fatigue, drowsiness, and so on) of cold-induced illnesses.
  • Avoid tasks that may cause excessive sweating.
  • Maintain energy and hydration by drinking warm caffeine-free, nonalcoholic beverages.
  • Stay in good physical condition.

Farm and Ranch Managers’ Responsibilities

If you are a farm or ranch manager, take the following precautions to keep your workers safe in cold and/or wet weather:

  • Allow workers to complete tasks at a comfortable pace and take extra breaks if needed.
  • In cold environments, be sure that workers always work in teams of two or more.
  • If a job needs to be completed outside, schedule the job for the warmest part of the day.
  • When possible, move outdoor jobs to an enclosed area.
  • Discourage workers from sitting or standing for prolonged periods during cold weather.
  • Allow workers to acclimate themselves to the cold before they begin a task.

Use the following format to cite this article:

Cold-related conditions and agriculture. (2012). Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://www.extension.org/pages/66813/cold-related-conditions-and-agriculture.

Sources

Chilblains. (2010) Mayo Clinic. Retrieved from http://www.mayoclinic.org/diseases-conditions/chilblains/home/ovc-20165478.

Cold stress guide. (n.d.) United States Department of Labor. Retrieved from https://www.osha.gov/SLTC/emergencypreparedness/guides/cold.html.

Frostbite: First aid. (2011) Mayo Clinic. Retrieved from http://www.mayoclinic.com/health/first-aid-frostbite/FA00023.

Hypothermia. (2011) Mayo Clinic. Retrieved from http://www.mayoclinic.com/health/hypothermia/DS00333.

Jepsen, S., McGuire, K., & Poland, D. (2011) Injury Prevention: Types of Cold Stress. The Ohio State University Extension. Retrieved from http://ohioline.osu.edu/factsheet/AEX-981.13.

Preventing cold-related illnesses in agricultural workers. (2011) Wyoming AgrAbility. Retrieved from https://wyomingagrability.wordpress.com/2012/01/20/preventing-cold-related-illnesses-in-agriculture-workers/.

Reviewed and Summarized By:
Linda M. Fetzer, Pennsylvania State University – lmf8@psu.edu
Karen Funkenbusch, University of Missouri  FunkenbuschK@missouri.edu
Dennis J. Murphy, Pennsylvania State University – djm13@psu.edu
Ron Odell, Cactus Feeders  ron.odell@cactusfeeders.com
Aaron M. Yoder, University of Nebraska Medical Center – aaron.yoder@unmc.edu