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Technical reference
IEC/BS EN 62305-1 - Lightning protection levels (LPL)
Lightning Protection Levels (LPL)
Four protection levels have been determined based on
parameters obtained from previously published technical
papers. Each level has a fixed set of maximum and
minimum lightning current parameters. These parameters
are shown in Table 6.
The maximum values have been used in the design of
products such as lightning protection components and
Surge Protective Devices (SPDs).
The minimum values of lightning current have been
used to derive the rolling sphere radius for each level.
For a more detailed explanation of Lightning
Protection Levels and maximum/minimum current
parameters please see the Furse Guide to BS EN 62305.
Table 6:
Lightning current for each LPL based on 10/350 μs waveform
LPL
I
II
III
IV
Maximum current (kA) 200
150
100
100
Minimum current (kA) 3
5
10
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Figure 3. The types of damage and loss resulting from a lightning strike on or near a structure
S1
Flash to the
structure
LEMP
Immediate mechanical
damage (Source S1)
Injury to people by
electric shock resulting
from resistive and
inductive coupling
(Source S1)
S3
Flash to a line
connected to the
structure
Fire and/or explosion due to the hot lightning arc itself, due to the resultant ohmic
heating of conductors, or due to arc erosion, i.e. melted metal
(Source S1)
.
Fire and/or explosion triggered by sparks caused by overvoltages resulting from resistive
and inductive coupling and to passage of part of the lightning current
(Source S1
).
Fire and/or explosion triggered by sparks due to overvoltages and lightning currents
transmitted through the connected service
(Source S3)
Injury to people due to touch
voltages inside the structure
caused by lightning currents
transmitted through the
connected service
(Source S3)
Failure or malfunction of internal
systems due to overvoltages
induced on connected lines
and transmitted to the structure
(Source S3 & S4)
or by
LEMP
(Source S1 & S2)
LEMP
Lightning
current
Induced
overvoltage
Induced
overvoltage
LEMP
LEMP
S2 Flash
near to the
structure
S4 Flash near
a line connected
to the structure