If there is a storm, lightning is the greatest danger to buildings and IT. A lightning strike can release current strengths of up to 200,000 amperes at voltages up to several hundred thousand volts. This enormous amount of electrical energy is released and dissipated within 50 to 100 microseconds. A lightning strike of this magnitude at a distance of approximately two kilometres will still cause voltage spikes in the electrical cables of a building that could destroy sensitive electronic devices. The risk of this indirect damage increases the closer a building is to the lightning.

If a building is struck directly by lightning, major damage can be caused by the dynamic energy released. This may affect the roof and façade, for example, and subsequent fires or surges can also damage electrical devices.