The purpose of a lightning protection system intercept this voltage, providing a safe path for lightning current into the ground. They do not decrease the likelihood your home may be struck, but provide a direct path to ground, preventing damage to your home from fire, explosion, and electrical surges that can result from lightning strikes.
Do I need Lightning System? Well, according to a number of risk control publication, it is not a legal requirement for all buildings and structures to have lightning protection. However, the health and safety at work regulations do apply to most businesses. A surge or lightning protection device prevents damage to electrical equipment from over-voltage transient events by blocking or redirecting surge current to the ground instead of passing through the equipment. Surge protection is connected to a conductor on the line side of equipment.
A lightning protection system will not keep your house from being struck by lightning, but a properly installed system will instead provide a safe path from the site of the lightning strike (which is often on the roof) to the ground. This minimizes the damage your home will sustain. In most situations, it is not necessary to install lightning rods on your metal roof. Lightning strikes to homes are rare. If your roof is the highest point of a surrounding area, you may consider having a lightning safety system installed on your home.
On structures less than 30 metres (about 100 feet) in height, a lightning rod provides a cone of protection whose ground radius approximately equals its height above the ground. On taller structures, the area of protection extends only about 30 metres from the base of the structure. Lightning rods are pointed so a charge will be concentrated at the end. If the rod had a round end the charges would spread equally around its surface. As long as the air is prevented from ionizing it won’t conduct the lightning bolt. The purpose of the rod is to prevent ionization by discharging the ions in the air.