Re: Re: Mobile phone letter may increase lightning casualties worldwide
Mr. Leblanc's memory is indeed reliable. Most high school and college
physics books still claim that lightning prefers sharp pointed metal rods
due to the presence of electrical charges around the tip.
However, these claims have been disproved by Professor Charles Moore
and his team at the New Mexico Institute of Mining and Technology in 2000.
They exposed the blunt and sharp tipped metal rods (a.k.a. Franklin rods)
to natural lightning in the mountains of New Mexico for seven years and
discovered that only the blunt tipped rods were struck by lightning.
They found that the electric field above the blunt tipped rods were
higher than that of the sharp tipped rods due to the absence of electrical
charges. This made the blunt tipped rods better lightning receptors than
the sharp tipped ones.
Professor Moore also exposed the new lightning attractor rods, such
as the radioactive rods and the early streamer emission (ESE) rods, under
natural lightning and found that these rods were never struck by lightning
also. Hence, his studies suggest that the blunt tipped rods are better
lightning receptors than the sharp tipped rods, the radioactive rods or
the ESE rods.
The blunt tipped rods have recently been included in the American
lightning protection standard (NFPA780) and is likely to gain acceptance
in many other standards around the world.
Hence, those whose lightning protection knowledge is based on high
school or college physics need to update them with these recent findings.
They can find these information from reliable websites such as:
1) National Lightning Safety Institute (www.lightningsafety.com)
2) Lightning Safety Alliance (www.lightningsafetyalliance.com)
Competing interests: No competing interests