During a thunderstorm, negative static build up in the air and create thunder. In a home, electronics and appliances in use are constantly building up positive static that lingers on, in, and around the home.
These two charges begin pulling at each other and if they connect, lightning forms and strikes.
Within milliseconds, the lightning follows the path of least resistance to the ground which is usually the electrical system or the gas line.
If it does ground itself through the gas line, which happens all to often in Texas, the possibility of a fire is very high.
The lightning rods are placed at the most vulnerable places on the roof. Connecting each of the lightning rods together is the conductor cable.
The conductor cable is brought down to at least two different places to a grounding rod. The ground rod is buried minimum of ten feet deep and connected with a clamp.
The material is either copper, aluminum, or a combination of both depending on the type of structure and budget.