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Figure 3.3.1.2 DEHN Risk Tool, division into zones Figure 3.3.1.3 DEHN Risk Tool, evaluation

must be defined for every supply line. These parameters are ¨ L1; Loss of human life
included in the line-related risks for the structure. If the line ¨ L2; Loss of service to the public
length is unknown, the standard recommends to use a line
length of 1000 m for calculation. The line length is defined ¨ L3; Loss of cultural heritage
from the entry point into the object to be protected to the con- ¨ L4; Loss of economic value
nected structure or a node. A node is, for example, a distribu- When defining the losses, it must be observed that losses al-
tion point of a power supply line on a HV / LV transformer or ways refer to the relevant type of loss. Example: Loss of eco-
in a substation, a telecommunication exchange or a piece of nomic value (risk R 4 ) due to touch and step voltage only ap-
equipment (e.g. multiplexer or xDSL device) in a telecommu- plies to the loss of animals, not to the loss of persons.
nication line. In the DEHN Risk Tool the result of a risk analysis is displayed
In addition to line-related parameters, the properties of the in the form of graphics (Figure 3.3.1.3). Thus, it can be seen
building must also be defined. For example, the following fac- immediately and at any time how high the relevant risks are.
tors are important: Blue stands for the tolerable risk, red or green for the calculat-
¨ External spatial shielding ed risk of the structure to be protected. To be able to correctly
¨ Spatial shielding in the building assess the risk potential for a structure, the risk components of
the relevant risk must be considered in detail. Each component
¨ Floor properties inside / outside the structure
describes a risk potential. The aim of a risk analysis is to spe-
¨ Fire protection measures and cifically reduce the main risks by means of reasonably chosen
¨ Risk of fire measures.
The risk of fire is an important decision criterion and basi-
cally defines whether a lightning protection system must be Each risk component can be influenced (reduced or increased)
installed and which class of LPS is required. The risk is assessed by different parameters. The measures shown in Table 3.3.1.1
2
according to the specific fire load in MJ/m . The following defi- make it easier to select protection measures. The user must
nitions are provided in the standard: make this selection and activate the protection measures in
¨ Low risk of fire: Specific fire load ≤ 400 MJ/m 2 the software.
¨ Ordinary risk of fire: Specific fire load > 400 MJ/m 2 To calculate the risk R 4 “Loss of economic value”, costs must
be calculated according to IEC 62305-2 (EN 62305-2). To this
¨ High risk of fire: Specific fire load ≥ 800 MJ/m 2 end, the actual state (without protection measures) and the
¨ Explosion zone 2, 22 desired state (with protection measures) must be considered.
¨ Explosion zone 1, 21 The following costs (in €) must be defined for calculation:
¨ Explosion zone 0, 20 and solid explosives ¨ Costs of animals c a
To complete the risk analysis, possible losses must be selected. ¨ Costs of the building c b
Losses are subdivided according to the type of loss: ¨ Costs of internal systems including their activities c s

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