classifies the
sources and types damage evaluated and introduces the risks
or types loss anticipated result lightning activity.
This standard thus sets out defined set of
lightning current parameters where protection
measures, adopted accordance with its
recommendations, will reduce any damage and
consequential loss result lightning strike.—
Technical reference
IEC/BS 62305-1 General principles
This opening part the IEC/BS 62305 suite standards serves as
an introduction the further parts the standard.
Part the standard also introduces new
concepts for consideration when preparing a
lightning protection system, such Lightning
Protection Zones (LPZs) and separation distance.
Furthermore, defines the relationships between
damage and loss that form the basis for the risk
assessment calculations part the standard.
—
Table Damage and loss structure according to
point lightning strike (IEC/BS 62305-1 Table 2)
Point strike Source of
damage
Type of
damage
Type loss
Structure L1, L4**
D2 L1, L2, L3, L4
D3 L1*, L2, L4
Near Structure L1*, L2, L4
Lines connected
to the structure
S3 L1, L4**
D2 L1, L2, L3, L4
D3 L1*, L2, L4
Near Line L1*, L2, L4
*Only for structures with risk explosion and for hospitals other
structures where failures internal systems immediately endangers
human life
**Only for properties where animals may lost
105
TECHNIC REFERENCE IEC/BS 62305 GENER PRINCIPLES
.
This reduction damage and consequential loss
is valid provided the lightning strike parameters
fall within defined limits, established Lightning
Protection Levels (LPL). However,
in practice not possible indeed cost
effective such lengths.
System design criteria
The ideal lightning protection for structure and
its connected services would enclose the
structure within earthed and perfectly
conducting metallic shield (box), and addition
provide adequate bonding any connected
services the entrance point into the shield.
These are used the basis for the selection and
implementation the appropriate protection
measures detailed parts and the standard.
This essence would prevent the penetration
of the lightning current and the induced
electromagnetic field into the structure.
Damage and loss
IEC/BS 62305 identifies four main sources of
damage:
• Flashes the structure
• Flashes near the structure
• Flashes the lines connected the structure
• Flashes near the lines connected the
structure
Each source damage may result one more
of three types damage:
• Injury living beings electric shock
• Physical damage (fire, explosion, mechanical
destruction, chemical release) due lightning
current effects including sparking
• Failure internal systems due Lightning
• Electromagnetic Impulse (LEMP)
The following types loss may result from
damage due lightning:
• Loss human life (including permanent injury)
• Loss service the public
• Loss cultural heritage
• Loss economic value (structure, its
content, and loss activity)
The relationships all the above parameters
are summarized Table 1.
Lightning current parameters are defined
