LIGHTNING PROTECTION SYSTEM

Lightning Protection System

A lightning protection system typically includes a rooftop network of electrical conductors, multiple conductive paths from the roof to the ground earthing, bonding connections to metallic objects within the structure and a grounding network.

        Lightning protection systems are installed on structures, trees, monuments, bridges or water vessels to protect from lightning damage. Individual lightning rods are sometimes called finials, air terminals or strike termination devices.

(Sources: Pinterest)

Conventional Lightning Protection System Installation

External & Internal Lightning Protection System (LPS)

Function of an external lightning protection system

· Interception of direct lightning strikes via air-termination system

· Safe discharge of lightning current to earth via down-conductor system

· Distribution of the lightning current in the ground via an earth-termination system

Function of an internal lightning protection system

· Prevention of dangerous sparkling in the structure by establishing equipotential bonding or keeping a separation distance between the LPS components and other electrically conducting elements

Component of lightning protection system 

Air Termination System

Lightning rod is a metal rod mounted on a structure and intended to protect the structure from a lightning strike.In lightning protection system, lightning protection rods are placed at regular intervals on the highest portions of a structure.

If lightning hits the structure, it will preferentially strike the rod and be conducted to ground through a wire instead of passing through the structure, where it could start a fire or cause electrocution.

(Sources: Chairish)

Made up of vertical air terminals and / or a lattice of copper conductors on the roof and edges of the structure. Since no part of the roof should be more than 5m from the nearest horizontal earthing conductor.

Traditional taper-pointed air terminals are not as frequently used today but when they are they should be positioned near those points where a strike is most likely to hit the building.

 (Source:google.com)

(Source:google.com)

The system is acceptable, provided an imaginary sphere never intersects the surface of the structure to be protected without settling on the components of the air termination. In principle, the mesh size determines that any point on the roof is nearer to the air termination network than half the side of a mesh.

The Hungarian Standard for Lightning Protection of Structures specifies the degree of the air termination systems according to combinations of several classifications, namely, the class according to function of structure, the class according to height and surroundings, and the class according to materials of the roof.

Down-conductor Termination System 

Down conductor is a material which contains movable electric charges. In a lightning protection system, the conductor connecting the air terminal or overhead ground wire to the earth electrode subsystem for making a discharge path.

(Sources: DIGTY CREW)

(Sources:google.com)

The purpose of the down conductor is to provide the low impedance path from the air termination system to the earth system. There is typically one down conductor for every 20m or part thereof the building perimeter at roof or ground level. If the building is above 20m in height or of an abnormal risk this distance should be reduced to 10m. Any good conductor which forms part of the building structure can be employed as a down conductor with appropriate connection to the air termination and earthing systems. For down leads not part of the structure, copper earth tapes and aluminium earth tapes are the most widely used materials.


Earthing system defines the electrical potential of the conductors relative to that of the Earth's conductive surface. Lightning protection systems are special grounding systems designed to safely conduct the extremely high voltage currents associated with lightning strikes. In an electrical installation an earthing system or grounding system connects specific parts of that installation with the Earth's conductive surface for safety and functional purposes. The point of reference is the Earth's conductive surface.

Earth-conductor Termination System

  (Source:google.com)

Each down conductor, or copper earth tape,  must have its own earth electrode termination and the resistance to earth of the whole system must not be greater than 10 Ohms without taking into account bonding to other services. The most common terminations are copper earth rods driven into the ground. These should be a minimum of 9 metre for the whole system.The individual earth electrodes are sometimes interconnected by a ‘ring conductor’ to help reduce the overall resistance. This should be at least 0.6m below ground level and preferably pass below incoming services. The ring conductor is made from copper tape or cable (aluminium is not permitted for use below ground) and also helps to provide potential equalisation at ground level, in addition to potential grading.The earth system should be designed as a whole since the complete installation should rise in potential together, to avoid excessive voltage differences. For this reason, the earth termination should be bonded to the rest of the earth electrodes.                                                                                                                 

(Sources:google.com) 

(Sources: Electrical technology)

        Earthing system

(Sources: IndiaMART)

Earthing rod

   Example on failure of ESE air terminals in Malaysia

(Sources: www.ground.co.kr)

(Sources: www.ground.co.kr)

(Sources: www.ground.co.kr)

(Sources: www.ground.co.kr)

(Sources: www.ground.co.kr)

    Damages by lightning (Lightning injuries)

 Fire Damage

The biggest threat lightning poses to a structure is fire. Wood and other flammable construction materials can easily explode when exposed to the high temperature of a lightning strike. Lightning current travelling through wires and pipelines instantly burns them up causing complete damage to property.

Health Effects

Lightning current which flowing through the victim's body resistance may develop a high voltage sufficient to flash around the skin or clothing to the ground in a direct strike, resulting in a surprisingly benign outcome. Besides, lightning may also effects on skin burns while the intense electric current can cause a loss of consciousness; it is also speculated that the EMP created by a nearby lightning strike can cause cardiac arrest.

Destruction of Electrical Equipment

Lightning is the biggest cause of damage of electrical equipment in industrial facilities, commercial buildings and homes. The bolt of lightning found its way down the mains cable and destroyed / burnt out what were a distribution boards within a school where we carry out regular work.

While the exact cause of lightning is still uncertain, scientists know it happens when clouds filled with water and ice rise rapidly. It is thought the heat causes the clouds to soar creating a lightning strike.

Source: Google image

Surges – underestimated risk.

The function of a lightning protection system is to protect structures from fire or mechanical destruction and to prevent that persons in buildings are injured or even killed. An overall lightning protection system consists of external lightning (lightning protection/earthing) and internal lightning protection (surge protection).                                   

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