Earthing & Lightning Protection System
Why do earthing and bonding need to be checked?
If you are having an alteration of addition made to your electrical installation, your electrician must check (as well as other things) that the earthing and bonding arrangements you have are up to the required standard.
This is because the safety of any new work you have done (however small) will depend on the earthing and bonding arrangements.
The purpose of a lightning protection system for a building is to provide a path for the lightning strike to pass through without damaging personnel or sensitive equipment in the building. A lightning protection system provides a low-resistance path for the strike to flow through.
What is Lightning Protection Testing?
A Lightning Protection Test (LPT) involves all lightning conductors and earth grounding installations being visually inspected and tested by a qualified Electrical Engineer.
Each individual earth grounding point and its conductors are electronically tested for resistance to ground.
An LPT also includes:-
-Performing random continuity tests, especially continuity of those parts of the Lightning Protection System which were not visible for inspection during the initial installation and are not subsequently available for visual inspection.
-The resistance to earth of each local earth electrode and, where practical, the resistance to earth of the complete earth termination system. Each local earth electrode should be measured in isolation with the test point between the down conductor and earth electrode in the disconnection position. If the resistance to earth of the earth termination system as a whole exceeds 10ohms, additional electrodes should be installed, where practicable, to obtain the requisite resistance value. If there is a significant increase in the value of the earth resistance from previously measured values, additional investigations should be made to determine the reason for the increase and measures taken to improve the situation.
-The results of a visual check of all conductors, bonds and joints or their measured electrical continuity.
Why Should I have it carried out?
-Lightning protection systems should be tested in accordance with the relevant British Standard. Also if a building with a poorly maintained system or a defective earth installation is struck by lightning or static electricity this can result in ‘flash-over’ to other metals within or on the structure. This can take place even without a direct strike because all lightning conductors pick up static even if the storm is 4 miles away!
How often and when should it be carried out?
-An LPT should be carried out at maximum intervals of twelve monthly. We suggest that LPT’s are carried out at eleven month intervals to allow us to vary the seasons we test in over time.