To protect a home or building in the event of lightning a metal conductor or rod is mounted on the top of the building and electrically connected to the earth through a wire is known as conventional lightning rod (lightning conductor) or spike arrester. If lightning strikes it will preferentially strike the spike arrester, and be conducted harmlessly to ground through the wire, instead of passing through the building, where it could start a fire or cause electrocution.
The rooftop lightning spike rod is a metal strip or rod, usually of copper or aluminum. Lightning Spike 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.
Spike Lightning Arrestor is a very efficient hybrid lightning dissipater. When operating as a shield it reduces the potential between the tower and storm cell by transferring electrical charge to the adjacent ionizing air molecules. This transference represents dissipation or the controlled leakage of the charge, thus reducing the probability of a lightning strike. If the electric charge accumulation rate far exceeds the dissipation rate the spike arrestor will divert a lightning strike away from the protected equipment and toward a safe, predetermined path to earth.