the actual risk (Rn
) is
greater than its corresponding tolerable risk (RT
),
then protection measures must instigated. The ultimate aim
of the risk assessment quantify and if
necessary reduce the relevant primary risks i.
—
Technical reference
IEC/BS 62305-2 Risk management
IEC/BS 62305-2 key the correct implementation IEC/BS 62305-3
and IEC/BS 62305-4. The assessment and management risk now
significantly more depth and extensive than the approach 6651. While 6651 devoted pages
(including figures) the subject risk
assessment, IEC/BS 62305-2 currently
contains over 140 pages.:
• R1
risk loss human life (including
permanent injury)
• R2
risk loss service the public
• R3
risk loss cultural heritage
• R4
risk loss economic value
For each the first three primary risks, a
tolerable risk (RT
) set.
Each primary risk (Rn
) determined through a
long series calculations defined within the
standard.
It this iterative process shown the Figure to
the left that decides the choice indeed
Lightning Protection Level (LPL) Lightning
Protection System (LPS) and Surge Protective
Measures (SPM) counter Lightning
Electromagnetic impulse (LEMP).1 the
National Annex 62305-2.IEC/BS 62305-2 specifically deals with making
a risk assessment, the results which define the
level Lightning Protection System (LPS)
required. This data can sourced
in Table IEC 62305-2 Table NF. The
above process repeated (using new values that
relate the chosen protection measures) until Rn
is less than equal its corresponding RT
.
Identify the
structure
to be
protected
For each loss be
considered identify
and calculate the risk
components RX
that
make risk Rn
RA
+RB
+RC
+RM
+
RU
+RV
+RW
+RZ
Calculate
Rn
= Rx
Install
protection
measures
in order to
reduce Rn
Rn
≤ RT
Structure adequately
protected for this type
of loss
For each loss be
considered identify
the tolerable level
of risk RT
Identify the types
of loss relevant to
the structure to
be protected Rn
• R1
risk loss of
human life (including
permanent injury)
• R2
risk loss of
service the public
• R3
risk loss of
cultural heritage
NO
YES
The first stage the risk assessment to
identify which the four types loss (as
identified IEC/BS 62305-1) the structure
and its contents can incur.
108 FURSE® EARTHING LIGHTNING PROTECTION
QUALIT SOLUTIONS FOR SAFEGUARDING PEOPLE, STRUCTURES AND SERVICES
.
—
01
—
01 Procedure for
deciding the need
for protection
(IEC/BS 62305-1
Figure 1). the actual risk (Rn
) less than equal
to the tolerable risk (RT
), then protection
measures are needed.e
