Inspection and Maintenance of LPS

Introduction:

Lightning Protection System (LPS) components tend to lose their effectiveness over the years because of corrosion, weather-related damage, mechanical damage and damage from lightning strokes. Hence, the condition of all the components of LPS should be checked periodically, to ensure the safety of structure and life of the beings connected with the structure. Inspection and maintenance shall not be conducted during threat of thunderstorms. IS/IEC 62305-3 explains about the inspection, testing and maintenance procedures for Lightning Protection System and the details are as follows.

Inspection of LPS:

Since the components of LPS (air-terminal, down conductor, clamps, fixing assembly) are exposed to atmosphere, they are more prone to corrosion and direct lightning strikes which may reduce the performance of the system. Hence the LPS should be inspected periodically.

The inspection includes checking technical documentation, visual inspections, testing and logging in an inspection report. The purpose of this inspection is to ensure that the LPS conforms to this standard in all respects. The interval between the inspection can be determined based on the following factors.

• Classification of structure protected (based on effects of damee).
• Class of LPS.
• Local environment (Ex. Corrosive environment, chemical usage).
• Materials of individual LPS components (Copper, SS, GI).
• Type of surface.
• Type of soil.

IS/IEC 62305 part 3 suggests the maximum time period between the inspection for the different classes of LPS and the details are as follows.

The LPS should be visually inspected at least once in every year. For areas with extreme weather conditions, the inspection should be done more often than normal conditions. A total inspection and test should be completed every two to four years.

Visual Inspection:

Visual inspections should be made to make sure that,

• The design was as per the standard.
• The LPS is in good condition.
• There are no loose connections.
• There are no accidental breaks or damages. There should not be any signs of corrosion.
• All the connections are proper.
• There should be any additions to the protected structure.
• Proper equipotential bonding should be established.
• Separation distances are maintained.

Testing:

• Performing continuity tests.
• Performing individual and combined earth resistance measurements of the earth

termination system. The results should be recorded in an LPS inspection report. 

• If the resistance to earth of the earth-termination system as a whole exceeds 100 the value can be improved by installing additional earth electrodes.

  An LPS should be inspected whenever any modification or repairs are made to a protected structure and also following any known lightning discharge to the LPS. The results of testing visual inspection, condition of air terminals and conductors, effects of corrosion, condition of joints and earth resistance values measured should be documented in an LPS inspection report.

  If an inspection shows that repairs are necessary, those repairs should be executed without delay and not be postponed until the next maintenance cycle.

  Maintenance of LPS:

  The LPS should be maintained at regular intervals to ensure that it continues to fulfil the requirements throughout the lifetime of the system. LPS maintenance should become a part of the overall maintenance schedule of the structure.

  The frequency of maintenance of an LPS depends on the following factors.

  • Weather and environment
  • Exposure to actual lightning strike
  • Level of protection

  Maintenance procedure contains a list of routine items to be checked to ensure the proper operation of the system. The maintenance procedure for LPS should contain the following items.

  • Verification of all LPS components;
  • Verification of the electrical continuity.
  • Measurement of the earth electrode resistance values.
  • Verification of SPDs.
  • Re-fastening of the components.

  All the maintenance activities carried out for LPS should be recorded and the records should include the details of corrective actions taken. The maintenance report helps us to evaluate the components of LPS and the installation procedure. The maintenance records can be used to update the maintenance procedures to prevent the damages.