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ined case. Table 3.2.8.1 gives an overview of typical lightning
Identify the structure to be protected and surge protection measures and their impact on the risk
components.
Identify the types of loss relevant to the structure

3.2.9 Loss of economic value / Profitability of
For each type of loss, identify and calculate protection measures
the risk components R A , R B , R C , R M , R U , R V , R W , R Z
In addition to the types of loss of public interest L1 to L3, the
type of loss L4 (loss of economic value) is relevant for many
No Structure structures. It has to be compared whether the protection meas-
R > R T ures make economic sense, namely if they are profitable.
protected
Thus, the standard of comparison is not an absolute parameter
Yes like the specified tolerable risk R T , but a relative parameter:
Protection needed Different states of protection of the structure are compared
and the optimum state of protection (costs of damage result-
ing from lightning strikes are as low as possible) is implement-
Is LPS Yes Are SPM ed. Several possibilities can and should be examined. The flow
installed? installed? chart according to IEC 62305-2 (EN 62305-2) (Figure 3.2.9.1)
No No Yes shows the basic procedure.

No The costs of the total loss C L in the structure are calculated by
the sum of the loss in the individual zones C LZ :
R A + R B + R U + R V > R T
Yes
C = R c
LZ 4Z t
Calculate where
new values Install an Install Install other R 4Z is the risk related to the loss of value in the zone with-
of risk adequate adequate protection
components LPS SPM measures out protection measures;
c t is the total value of the structure (animals, building,
contents and internal systems including their activities
in currency) (see section 3.2.5).
Figure 3.2.8.1 Flow diagram for determining the need of protection
and for selecting protection measures in case of types
of loss L1 to L3 If protection measures are taken, the loss is reduced. However,
it is never reduced to zero since there is a residual risk. The
costs C RL for the total residual loss in the structure in spite of
R U , R V , R W and R Z , it is possible to specifically select lightning protection measures are calculated by the sum of the remain-
protection measures for a particular structure. The flow chart ing loss in the individual zones C RLZ :
in IEC 62305-2 (EN 62305-2) (Figure 3.2.8.1) illustrates the
procedure. If it is assumed that the calculated risk R exceeds C = R ' c
the tolerable risk R T , it must be examined whether the risk of RLZ 4Z t
electric shock and physical damage caused by a direct light- where
ning strike to the structure and the incoming lines (R A + R B + R’ 4Z is the risk related to loss of value in the zone with
R U + R V ) exceeds the tolerable risk R T . If this is the case, an ad- protection measures.
equate lightning protection system (external and / or internal
lightning protection) must be installed. If R A + R B + R U + R V is In case of a single zone, the following applies:
sufficiently small, it must be examined whether the risk due to
the lightning electromagnetic pulse (LEMP) can be sufficiently C =C LZ or C RL =C RLZ
L
reduced by additional protection measures (SPM).
If the procedure according to the flow diagram is observed, The annual costs C PM for protection measures can be calcu-
protection measures which reduce such risk components lated by means of the following equation:
with relatively high values can be selected, namely protection
measures with a comparatively high effectiveness in the exam- C =C (i +a +m)
PM P

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