lightning flash over Signal Iduna Park in Dortmund

Germany vs Denmark was suspended for about 25 minutes on Saturday night while a fierce lightning storm struck overhead at Euro 2024. Lightning storms like these pose a significant threat to life.

For some football fans in the sold-out 81,000-seater stadium, they enjoyed the conditions of torrential rain and claps of thunder, against the backdrop of severe lightning flashes. This lightning storm, however, reminded us about the importance of having adequate earthing systems and lightning protection systems installed at your facility, to mitigate the dangers of such lightning storms.

Here, LPI Engineering Manager Hadi Beik Daraei breaks down the importance of having a compliant and adequate lightning protection system to protect tall structures of over 100 metres in height.

Figure 1: Lightning Flashes at Euro 2024 over Signal Iduna Park

Lightning Flashes at Euro 2024 (image Hecko90 via X)

The above figure (figure 1) shows lightning flashes and no strikes. This means a lightning flash is observed when the charge is discharged in a region of opposite polarity charge within the same cloud or a neighbouring cloud.

The exact path an ionization channel takes is uncertain and numerous changes in direction are common giving lightning the familiar jagged appearance.

lightning flashes over Dortmund Stadium

Figure 2: lightning flashes over Dortmund Stadium (image via @SebStanbury on X)

Figure 2 depicts what appears to be a cloud-to-ground lightning strike. In this case, a return stroke follows the lightning flashes and establishes the lightning strike. The charge is then discharged to the earth.

Why is this Important?

Lightning flashes and strikes are happening around the area where a significant number of people are gathered to watch a game for a short duration of only 90 minutes!

Lightning flashes over Dortmund

Figure 3: Lightning flashes over Dortmund

Tip 1

Each lightning flash is different due to the natural variations in the thundercloud that produced it and the individual paths to the ground. For example, it is not possible to predict that the next lightning flash to a particular structure will have a peak current of a given value.

What can be said is that the structure has a given probability of being struck by a lightning flash with current parameters exceeding a certain value.

Tip 2

The recorded values of peak lightning current produced by a single stroke are in the range of 2 kA to 300 kA. The median value of peak lightning current is approximately 30 kA with median values of charge transfer and specific energy of 5 C and 55 kJ/Ω, respectively.

In addition, the electrical characteristics of a lightning current vary with the type of lightning flash, season of the year and geographical location.

Tip 3

Tall structures will attract a forming channel whose last prior steps are within the Strike Distance. In other words, tall structures could have a role in triggering the last prior steps of charges to the tall structures. This means that the highest part of the stadium structure can attract the charging path.

Also, the pointed parts of a structure (Limited Surface area) intensify the electrostatic fields of the earth, which become charged as the developing channel approaches.

Lightning Protection Risk Assessment

Before the design of a lightning protection system, a risk assessment must be performed. The following questions must be answered by an experienced engineering specialist:

  1. Based on the geographical location, season of the year, and its collective area, to what extent is the stadium exposed to direct strikes?
  2. Is human loss due to direct strikes a concern in this situation, or should only secondary effects be considered in the risk assessment for human loss?
  3. What is the level of natural bonding between structures that are not normally exposed to people?
  4. How many factors are linked to any safety measures that could be affected by the direct and indirect effects of possible lightning strikes?
  5. Regarding the structural characteristics, does the structure have the potential to be part of a lightning protection system (LPS)?
  6. How many lightning protection zones need to be considered in the stadium?
  7. Are there any specific locations where people can be outside the internal (LPZ) lightning protection zone? If so, for how long?
  8. What type of exterior and interior protection needs to be considered, and to what extent, to reduce the risk within allowable limits?

Speak to our Technical Team

Our technical engineering team have designed, installed, and commissioned over 15 projects in Germany since 2018. With a registered GmbH in Frankfurt and a warehouse strategically located, our teams are ready to protect your structure and its occupants against damages and loss of life.

Featured Image credit image via @SebStanbury on X.