Originally invented by Benjamin Franklin
in the 18th century, lightning rods (now
often called air terminals) are designed
to protect buildings or important pieces
of equipment from being damaged by lightning
strikes. Lightning is a random and unpredictable
event involving the discharge of atmospheric
electricity between clouds and the ground,
usually occurring during stormy weather.
Lightning rods do not attract lightning --
the lightning will strike regardless of whether
the structure is protected by a rod, since
modern construction using metal pipes, wires,
and fixtures are better electrical conductors
and thus make structure more likely paths..
Lightning rods are designed to provide an
even more favorable path for the lightning
to travel so that the enormous electrical
current contained in the strike will not
result in heat or fire damage.
Since lightning rods should be taller than
the structure they are protecting, they are
often mounted on the roof. The rod itself
is usually a two inch diameter spike that
is connected to a piece of copper or aluminum
wire that is about an inch in diameter. The
wire should be connected to a conductive
grid buried in the ground nearby. The simplest
rods are metal spikes, but rods that incorporate
ornamental designs or that resemble weather vanes are also available.
Many people believe that surge suppressors (or protectors) will protect their electronics from being
damaged by lightning strikes, but this is
not the case. Surge protectors only protect
against surges of electricity coming through
the electrical lines from the power company.
A properly installed lightning rod is necessary
to protect against lightning travelling through
the structure of the building.
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