In case of lightning activity, step and touch voltage risk can occur in an area of 3 m around the place where the lightning current enters the soil.
This channel can be well known for example when there are only down-conductors on a wooden structure. However, in many cases the lightning current will split between various paths (structure metallic frame, metallic façade covering, electrical conductors, pipes …) existing in a structure.
This risk can be reduced by insulating people feet from the ground, for example a thickness of 5 cm of asphalt. However this thickness is difficult to check in practice and the effect of a top layer of rain water is not clear.
A new product : a mat named “EPR” that is provided like a portable carpet 3.2 mm thick, size 1.0 m x 1.5 m based on 3 layers :
- Top : non conductive rubber
- Medium : Stainless steel
- Bottom : conductive rubber