Weathervanes, Lightning Rods

A lightning rod (or lightning protector) is a metal strip or rod, usually of copper or similar conductive material, used as part of lightning safety to protect tall or isolated structures (such as the roof of a building or the mast of a vessel) from lightning damage. more...

Its formal name is lightning finial or air terminal. Sometimes, the system is informally referred to as:

• a lightning conductor,
• a lightning arrester, or
• a lightning discharger.

However, these terms actually refer to lightning protection systems in general or specific components within them.

Arrestors

A lightning arrestor is a device that shunts or diverts the massive voltage and electrical current of a lightning strike to an earthed ground. Electrical equipment can be protected from lightning by an arrester, a device that contains one or more gas-filled spark gaps between the equipment's cables and earth. An arrester is designed to handle much higher jolts of electricity than a surge protector, which cannot handle a direct strike at all.

Should lightning strike a building, the current will travel through the conductor rather than through the fabric of the building, causing less damage. Should lightning strike one of the cables, the high voltage will cause the gas in the spark gap to break down and become a conductor, providing a path for the lightning to reach the ground without passing through the equipment. It typically involves a spark gap, across which a normal voltage cannot arc.

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