The Lightning Debate

April 11, 2011

The case in support of a lightning policy

Kevin Johnston, M.S.
Graduate Faculty, University of Idaho
Senior Consultant, Professional Aquatic Consultants International

Why is there even a debate? The most conservative perspective is to close both outdoor and indoor pools due to the potential risk. The most liberal perspective: the pool is a safe place based on its design and there hasn’t been a documented ‘in the water’ injury or death in an indoor pool as a result of lightning. Our society has become what Beck calls a ‘Risk Society’. Risk is out there lurking in the shadows but is obscure and abstract: global warming, terrorist attacks and nuclear disasters waiting to happen. Lightning and the indoor pool can be seen in these same terms.

Existing State and National Standards
A number of national codes and standards specifically apply to and explicitly state indoors pools in their regulations. These include the American College of Emergency Physicians, National Lightning Safety Institute, National Athletic Training Association (NATA) and the Young Men’s Christians Association (YMCA). There are also a number of national organizations with lightning standards having relevance to pools which may not differentiate indoor and outdoor but plainly state swimming pools. These include the National Weather Service, American Meteorological Society and the NCAA Guideline #1D.

The NATA lightning position statement specifically governs all outdoor activities and indoor pools:
“Even though a swimming pool maybe indoors and apparently safe, it can be a dangerous location during thunderstorms. The current can be propagated through plumbing and electric connections via the underwater lights and drains of most pools…following these pathways to the swimmers through the water.”

Six states have codes related to lightning. Washington Administrative Codes requires the operator to take the appropriate action during environmental conditions like lightning. Delaware’s code states that, ‘during electrical storms use of a pool (indoor or outdoor) shall be prohibited.’ Nebraska requires that pools be closed during electrical storms.

Actually Documented Lightning & Indoor Pool Incidents
The YMCA, owner of more swimming pools than any other single agency in the United States, recorded lightning entering into one of their natatoriums. Fortunately they had been following the YMCA’s national guideline to clear their pools thus averting the potential for a lightning injury or death. There have been other near misses: structural damage of an indoor pool’s roof; minor injuries to an indoor pool employee due to contact with a breaker panel; destruction of a main circulation pump motor; injuries sustained while on a telephone and in the showers. Additionally, there are records of visible lightning in natatoriums located in Florida, Georgia and Tennessee. Given these examples, one must take precautionary action.

The Potential Risks
The following are some questions to consider. Could swimmers in an indoor pool be injured or killed by a lightning strike? Would it be one swimmer or all of the swimmers in contact with the water? Is it just luck that we haven’t had an accident, or is it because of building design? Could it be that the lack of an accident is due to the preventive measures that many operators have taken, such as clearing indoor pools during lightning?

Conduits (electrical, gas, water, sewer, phone, recirculation system) can carry the electrical charge of lightning and distribute it elsewhere. Building design can mitigate this factor by bonding and grounding the pool. However, electrical bonding and grounding is designed for manmade voltage gone astray and most strikes, while the larger lightning strikes can be 25,000 to 50,000 amps, 2 million volts and over 50,000 degrees F. The risks are high with lightning of this magnitude and scale as it may not take the path of least resistance (as usual), rendering bonding and grounding ineffective.

It is also well documented that those in contact with domestic water sources (sinks, bathtubs and showers) are at risk. There are known deaths and injuries in these environments associated with household water in homes that were bonded and grounded to code. Therefore you have to ask if this could happen in an indoor pool as well.

Buildings constructed using steel beams, steel roofing, with no windows are safer than others. For example, the University of Minnesota Natatorium remains open even during severe lightning activity, and has been directly struck half a dozen times. However, they are in the fortunate situation of being able to afford a lightning protection system.

A lightning protection system consists of air and ground terminals connected by a conductive system, which must be continuous to work. A building’s structural steel is sometimes part of this conductive system. Since lightning takes the path of least resistance, discharges are attracted to air terminals, which extend 18” above the top of the building. The current passes through the conductors to the ground terminals, where it is dissipated to the earth. Lightning protection should include a continuous conductive system with air terminals and ground terminals installed. Most pools do not take all these protective design measures into consideration.

When evaluating the risks at your indoor pool, ask the following questions: Is your bonding and grounding system intact? What is the maximum voltage that your grounding system can sustain? Do you have a functioning lightning protection system in place?

I contend that the erring on the side of caution by completely clearing the water/showers and preventing the use of phones is the only near-failsafe way of reducing the risk of electrocution during lightning’s threat at indoor pools.

Important lightning safety policy elements:
– Generate an action plan and communicate to everyone involved.
– Devise a plan to alert people when they need to seek shelter.
– Create a system to identify lightning and monitor weather
– Identify safe-shelter locations before warnings.
– Notify all persons when the threat has passed.
– Have persons trained in First Aid and CPR.

Lightning Response Action Plan
1. See lightning hear thunder = Clear pool
2. Avoid risks: avoid poles, metal fencing, lifeguard stands, ladder entrances, diving board stanchions
3. Close pool area
Guards secure entrance to pool deck
4. Create holding area for patrons
Dry, with no windows and avoids metal door frames
5. Prevent use of showers, landline telephones (except in an emergency)
Cordless & cellular phones are acceptable.
6. Create monitoring procedure
Signal all clear, leave holding area, reopen pools

Warning and Monitoring Systems need to be in place and could include:
1. Weather radio: National Oceanic and Atmospheric Administration (NOAA).
2. Weather pager
3. Weather services: Use the World Wide Web
4. Sensing devices (structure mounted, remote handheld)

Lightning Liability Concerns
Here are some additional questions to consider:
*What is your current lightning policy?
*Is your facility manager or head lifeguard trained in weather observation?
*How is training conducted?
*How would current policy hold up in court?

While lightning may legally be seen as an act of God, advances in technology make lightning a much more foreseeable event. Hence we should act to avert the potential risk at indoor pools related to lightning. We have a professional responsibility to manage that risk and not wait for it to create unnecessary injuries or deaths.

American Red Cross: Lifeguard Training, 2001, 16-17.
Andrews, C. J., M. A. Cooper, M. Darveniza, and D. Mackerras, 1992: Lightning Injuries: Electrical, Medical, and Legal Aspects. CRC, 184 pp. Walsh.
Johnston, K.M., 1999. Encyclopedia of Aquatic Codes and Standards (pg. 79).
K. M. Bennett, B., Cooper, M. A., Holle, R. L., Kithil, R., Lopez, R. E., 2000: National Athletic Trainers’ Association position statement: Lightning safety for athletics and recreation. J. Athletic Training, 35, 471-477
R. Kithil, June 2000. Lightning Safety Handbook, in press, Chapter title: “Swimming Pools: Water and the Lightning Hazards,” K.M. Johnston & L.D. Bruya, National Lightning Safety Institute, Academic Press
R. Holle, 1999, National Oceanic and Atmospheric Administration (NOAA) Storm Data (pg. 20-38).
Uman, M.A., 1986. All about lightning. New York, NY. Dover Publications
Waters, W.E., 1983. Electric Introduction from Distant Current Sources, Prentice Hall, Engelwood Cliff, NJ.
Wiley, S. 1998. Shocking news about lightning and pools. US Swimming Safety, 4:1-2.
YMCA, 2000, YMCA Safety & Risk Notes, Issue 3, August, YMCA Services Corporations. Available at

Other Sources
— Http://
– Weather forecasts specific to lightning:
— Http://
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– An indoor pool is a hazard and could be subjected the hazards of a lightning strike.
— Http://
– NCAA Guideline 1G on Lightning Safety
— Http://

Special thanks to C. Denison, & A. Bringle, University of Northern Iowa since this is an amended presentation we shared at the 2001 NIRSA Aquatic Symposium entitled “Severe Weather Protocols” and originally presented October 13, 2001 at Texas A&M

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