Touch voltage is the voltage acting on a person between his standing surface on earth and his hands when touching the down conductor.
In special cases, the touch voltage outside the building in vicinity to a down conductor can present a life hazard even if the lightning protection system is installed as per the standards.
The following measures reduce the risk that persons from being injured or even killed when touching the down conductor:
1) The down conductor is covered with insulating material (at least 3 mm cross-linked polyethylene with an impulse withstand voltage of 100 kV (1.2/50 μs)).
2) The position of the down conductors can be changed so that there is no human interference within 3m from the down conductor, e.g. Avoiding down conductor in the entrance area of the structure.
3) The probability of persons accumulating can be reduced by notes or prohibition signs. Barriers are also a possibility.
4) The contact resistance of the floor layer within a radius of 3 m around the down conductors is not less than 100 kΩ.
5) A 5 cm thick layer of insulating material, for example asphalt (or a 15 cm thick gravel layer), typically reduces the risk to an acceptable level.