Lightning Protection Systems
Risk Management
The task of assessing the risk of lightning inflicted damage to a structure and its internal sub systems is a complex procedure when considering all the factors such as the sources of damage, type of damage, type of loss and risk of loss. SPC offers an analytical approach for risk management in accordance with the procedure of IS/IEC 62325 -2. For designing lightning protection schemes, SPC Software computes tolerable limit of risk, calculates the actual risk and then evaluates the protection methods required to reduce the actual risk to be equal to or lower than the tolerable risk. The main outcome from this risk assessment is to select the minimum lightning protection level (LPL) that is used in the lightning protection design. Once the LPS is designed based on the LPL, risk management process is complete when the assessment is made with and without LPS to check for the adequacy.
Experience of SPC experts reveals lightning protection needs to be installed for certain ‘mission-critical’ installations even when the risk assessment process indicated that it is was not required. In few other situations where a direct lightning could cause fire & explosion, a higher LPL (than that required) was also selected to ensure a higher degree of protection.
Source of Damage
In order to evaluate whether or not lightning protection for an object/structure is needed, risk assessment is carried out in accordance with the procedures defined in the Standards.
The risks to be evaluated include:
Risk of loss of human life
Risk of loss of service to the public
Risk of loss of cultural heritage
Risk of loss of economic value
Each of the above-mentioned risks is broken down into individual risk components (sub categories), which are then evaluated with regard to direct and indirect lightning effects upon the structure and on the services connected to the structure like communication, electricity supply etc. This requires computation of the number of dangerous events, which is related to the structure size and lightning ground flash density in the area. Lightning ground flash density is the number of lightning flashes per sq.km per year that are recorded and mapped by various authorities worldwide (National Building Code -NBC 2016 in India).