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.