A lightning protection system is a passive means of preventing property damage from the effects of a lightning strike. It works by providing the electric charge produced by the clouds a path of least resistance to the ground. There are four main parts of a properly installed lightning protection system: copper air terminals, copper cable, copper clad ground rods, surge suppressors.

The air terminals and cable are typically copper, but sometimes they can (or must) be aluminum. All of the air terminals are connected via the cable which has a minimum of two ground rods buried 10 feet below grade. This system is then grounded to both the water pipes and existing ground of the circuit box. The surge suppressor can be connected to the breaker box to cover the entire electric system or they can be placed at individual appliances or electronics.

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 protection (lightning protection/earthing) and internal lightning protection (surge protection).

Functions of an external lightning protection system:

  • Interception of direct lightning strikes via an air-termination system

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

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

Functions of an internal lightning protection system:

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

Lightning equipotential bonding:

  • Lightning equipotential bonding reduces the potential differences caused by lightning currents. This is achieved by interconnecting all isolated conducting parts of the installation by means of conductors or surge protective devices.

Strike Termination

Strike termination devices serve the system function of accepting the direct lightning attachments.  They represent the umbrella against penetration of lightning to non-conductive building materials to guard against fire or explosion.


The conductor system component of complete lightning protection includes main sized cables, the structural steel of a building, and bonding or interconnection wires to internal grounded building systems.

Potential Equalization (Bonding)

The major current carrying components of the lightning protection system were described in their earliest form by Benjamin Franklin. Modern techniques for component manufacture and designs incorporating the system on.

Surge Protection

Lightning protection systems are designed first and foremost as fire protection systems – to stop the building from burning down and losing the people and equipment inside.

Inspection & Maintenance

The exposed components for a lightning protection system are copper, aluminum, or other metal designed to carry current, provide bonding connections, and remain functional in an open weather environment.

Risk assessment

Some structures are inherently more or less at risk of being struck by lightning. The risk for a structure is a function of the size (area) of a structure, the height, and the number of lightning strikes per year per mi for the region.

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