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  • Writer's pictureCOPTR GmbH

Thunderstorm warning systems in public outdoor swimming pools

Coptr Managing Director Philipp Kominek in an interview with Marco Hortz

How is operational safety increased with the help of the thunderstorm warning system?

"The warning system warns the pool staff and pool guests of life-threatening dangers such as lightning or storms. It works continuously without a break, using the latest technology and in accordance with the recognised rules of technology. Especially on hot and humid days with up to 30 thunderstorms, when the pools are also very busy, the pool staff can concentrate better on their core competence of water supervision and do not have to keep an eye on the weather situation at the same time. Safety and routine through always constant, regulated processes through fully automatic function and individual system configuration, instead of subjective decisions and coordination within the pool staff. Analogous to the chlorine gas alarm, the thunderstorm warning system also excludes the human factor from the measurement and alarm before the danger. The thunderstorm warning system also gives the all-clear signal. All lightning and storm measurement data, the system functions and the automatic instructions for action are documented to the second, as proof of the events."

What are the requirements according to "DIN EN IEC 62793 Lightning protection thunderstorm warning systems"?

"DIN EN IEC 62793 defines a thunderstorm warning system as follows: A system consisting of thunderstorm detectors capable of measuring lightning by its electromagnetic pulse and thus monitoring lightning activity in the danger zone. Furthermore, the system has tools to process the collected data to provide a human perceptible alarm (warning) regarding the lightning related events or conditions for a defined surrounding area. For this purpose, 2 monitoring radii with a warning area and an alarm area are required. The size and shape of the monitoring area should be adapted to the needs of the user. In this context, a clear procedure and protocol for alarm transmission should be defined to ensure that the alarm information is properly received by the end user.

DIN EN IEC 62793 identifies typical hazardous situations in which a thunderstorm warning system improves the protection of people. In particular, large open spaces and people involved in activities such as sports, water sports and leisure are mentioned here. Furthermore, DIN EN IEC 62793 concludes: If the safety of people can be affected by lightning events, a thunderstorm warning system should therefore be used. There are companies that use an alarm system (e.g. sirens) with fully automatic function for this purpose."

How does the thunderstorm warning system work in practice?

"The thunderstorm warning system works as follows: The thunderstorm warning system receives data of actually measured lightning in the vicinity of the bath in real time, accurate to within a few metres. The source of the measured data is the Europe-wide lightning detection system of the SIEMENS company. Based on scientific experience and recommendations, two monitoring areas of variable shape and size are individually defined for the bath in advance. An outer area as a pre-warning area and an inner area as an alarm area. If lightning is measured at an extended distance in the pre-warning area, there is an automatic pre-warning via a colour display (yellow) on the smartphone and, if desired, a separate monitor in the swimming pool attendant's office. If lightning is measured at a distance relevant to the safety of the bathers (alarm area), an automatic siren signal is given to interrupt bathing operations. The bath is to be evacuated, all persons are to go immediately to buildings/ cars protected against lightning. The pool staff and pool guests can read the current thunderstorm status (red) and textual instructions for action on their smartphones via the Internet and follow a 20-minute countdown to see how long it will take for the pool to be reopened. The countdown jumps back up to 20 if further lightning is measured in the alarm area. After the thunderstorm has passed and the 20-minute safety buffer has expired, the baths are also automatically reopened (green) via a siren signal. The existing ELA of the open-air bath can be integrated and predefined, verbal instructions for action automatically disseminated. If a weather station is also installed in the outdoor pool, warnings and warnings of storms can be automatically issued in addition to lightning strikes."

Which pools are suitable for installation?

"In all pool/sauna establishments that have an outdoor area."

What are the dangers of a thunderstorm in an outdoor swimming pool?
  • Injury and death due to direct or indirect lightning strike.

  • Flying parts (branches, wood splinters, sunshades, sunbeds, building cladding, etc.) due to the lightning strike and additional strong wind

  • Panic-like behaviour among bathers

  • Fire hazard due to possible ignition of flammable substances

  • Bathing staff may put themselves in danger in order to evacuate bathers who remain in the open areas. This happened, for example, in the case of Keidel-Therme in May 2018, see..:

In which areas, apart from public pools, is the system still used?

Sports facilities, professional football/young talent centres, Bundesliga stadiums, leisure parks, golf courses, regatta courses, horse racing tracks, event venues, industrial sites.

Can you please give us some additional information on the legal background?

"The basis for claims for damages due to lightning damage are, in particular, the so-called traffic safety obligations according to § 823 paragraph 1 BGB, or, in the case of publicly owned swimming pools, § 839 BGB in conjunction with Article 34 GG. According to case law, the operator of a sports facility, e.g. a swimming pool, has a fundamental duty to prevent hazards associated with the intended use of the sports facility (BGH in VersR 1980, page 67). The operator can also use other persons to fulfil the duties, in the case of swimming pools usually the swimming pool attendant. Particularly high obligations apply to children due to their inexperience and imprudence. The usual dangers in swimming pools also include the danger of a lightning strike. For example, the Deutsche Gesellschaft für das Badewesen e. V. (German Swimming Pool Association), together with the VDE Ausschuss für Blitzschutz und Blitzforschung (VDE Committee for Lightning Protection and Lightning Research), has drawn up DGfdB Guideline R 94.06 on the dangers of lightning storms. In addition, there are other standards that generally require the protection of guests and staff against weather hazards, e.g. § 23 regulation 1 of the accident insurance regulations (DGUV), §§ 3, 4 of the Occupational Health and Safety Act (Arbeitsschutzgesetz) or in the respective state building regulations.

The extent of the required road safety obligations depends on the respective state of the art, because what is required is what is technically possible and reasonable. Jurisprudence is also based on existing DIN standards or DGUV regulations, but considers compliance with them to be merely a minimum standard, which does not necessarily mean that all road safety obligations are fulfilled (BGH, NJW 2004, page 1449)."

Thank you for the sympathetic interview and continued success in making our outdoor pools safer.


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