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L F is the typical mean percentage of victims injured by additional loss of human life due to physical damage (L BE and
physical damage (D2) due to a dangerous event; L VE ) should be taken into account when assessing the total loss
L O is the typical mean percentage of victims injured by (L BT and L VT ):
failure of internal systems (D3) due to a dangerous L BT = L + L BE
B
event;
r t is a factor reducing the loss of human life depending L VT = L + L VE
V
on the type of ground or floor;
r p is a factor reducing the loss due to physical damage L = L = L FE t e
depending on the measures taken to reduce the con- BE VE 8760
sequences of fire; L FE Loss due to physical damage outside the structure;
r f is a factor reducing the loss due to physical damage t e Time during which person stay in dangerous places
depending on the risk of fire or explosion of the struc- outside the structure.
ture; If the time t e is unknown, t e / 8760 = 1 is to be assumed. L FE
h z is a factor increasing the loss due to physical damage should be provided by the body preparing the explosion pro-
when a special hazard is present; tection documents.
n z is the number of persons in the zone;
Unacceptable loss of service to the public
n t is the total number of persons in the structure; Loss of service to the public is defined by the properties of the
t z is the time in hours per year during which persons stay structure or its zones. These properties are described by means
in the zone. of reduction factors (r p , r f ). Moreover, the relation between the
IEC 62305-2 (EN 62305-2) specifies typical mean values for number of served users in the zone (n z ) and the total number
L T , L F and L O for roughly classified structures (Table 3.2.5.5). of served users in the structure (n t ) is important. There are up
These values can be modified and adapted for specific struc- to six loss values:
tures provided that the number of possibly affected persons, r r L F n Z
p
f
their independent mobility and their exposition to lightning L = L = n
B
V
effects are considered. For the values stated in Table 3.2.5.5, t
it is assumed that persons permanently stay in the structure. L = L = L = L = L n Z
O
A detailed assessment of L F and L O may be required for struc- C M W Z n
tures with a risk of explosion. In this context, the type of struc- t
ture, risk of explosion, division into explosion protection zones L F is the typical mean percentage of unserved users due
and measures to reduce the risk must be observed. to physical damage (D2) in case of a dangerous event;
If the risk for persons resulting from a direct lightning strike to L O is the typical mean percentage of unserved users due
a structure also affects surrounding structures or the environ- to failure of internal systems (D3) in case of a danger-
ment (e.g. in case of chemical or radioactive emissions), the ous event;
Type of damage Typical loss value Type of structure
D1: Injuries L T 10 -2 All types
10 -1 Risk of explosion
10 -1 Hospital, hotel, school, public building
D2: Physical damage L F 5 · 10 -2 Building with entertainment facility, church, museum
2 · 10 -2 Industrial structure, economically used plant
10 -2 Others
10 -1 Risk of explosion
D3: Failure of internal systems L O 10 -2 Intensive care unit and operating section of a hospital
10 -3 Other areas of a hospital
Table 3.2.5.5 Type of loss L1: Typical mean values for L T , L F and L O

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