An Overview of IS/IEC 62305 part 1

Introduction:

As per IS/IEC 62305 part 1, there are no methods or devices that can prevent lightning discharges. Lightning strikes on the structure or nearby structures will cause injury to the people and cause damage to the tructure themselves. Hence a properly designed and executed lightning protection measures is essential to reduce the losses caused by lightning strikes.

There are four parts of IS/IEC 62305 and the connection between the parts are shown below in Figure 4.

Scope:

IS/IEC 62305 part 1 provides general principles for protecting the structures and the people associated with the structure against lightning strikes.

The following type of structures are not considered in this standard

• Railway systems
• Vehicles, Ships, Air craft and offshore installations
• Underground high-pressure pipelines
• Pipe, power and tele communication lines.

Damage due to lightning:

The lightning current is the natural source of damage. The lightning can cause three basic type of damages and each damage will result in four different types of losses.

• L1: Loss or permanent injury to human life
• L2: Loss of service to public
• L3: Loss of cultural heritage
• L4: Loss of economic values

Among the losses, loss L4 will be considered as purely an economic loss.

The risks associated with the four types of losses are as follows

• R1: Risk of loss or permanent injury to human life
• R2: Risk of loss of service to public
• R3: Risk of loss of cultural heritage
• R4: Risk of loss of economic values

Proper preventive measures should be taken to avoid the damages in order to evaluate whether a lightning protection is needed for a structure or not, a risk assessment as per IS/IEC 62305-2 shall be made.

Lightning Protection Level:

As per IS/IEC 62305, there are four different levels of lightning protection and each level has its own parameters. Some of the parameters for the four lightning protection levels are shown below in Table 1.

Lightning Protection Zone:

Protection measures such as LPS, shielding wires, magnetic shields and SPD determine the Lightning Protection Zones (LPZ). The different zones are shown below in Table 2.

The different zones of protection are shown below in Figure.

Protection of structures and internal systems:

The structure to be protected shall be made to in LPZ OB or higher by installing lightning protection system (LPS). An LPS consists of both external and internal lightning protection systems.

The basic components of an external Lightning Protection System are as follows.

     1) Air terminal system

     2) Down conductor system

     3) Earthing system

The function of the internal LPS is to prevent dangerous sparking by using equipotential bonding, separation distance along with SPDs. The LPS shall comply with requirements of IS/IEC 62305 part 3 & part 4.