Do people still use lightning rods?
Yes. In fact, more lightning protection systems
are installed now than ever before. Today’s lightning protection
systems are inconspicuous. Since buildings
today are equipped with many sensitive electronic
systems, planners tend to include
lightning protection systems not only to protect
the structure but also to help protect the
electronic systems and to keep the
buildings up and running.
rods attract lightning?
No. This common misconception dates back
to Ben Franklin’s day. Lightning rods simply intercept
a lightning strike and provide adequate
pathways to safely conduct the lightning
to the ground. If lightning is zeroed in
on a particular location, it will strike
that location, whether there is lightning protection
in place or not. It is helpful to remember
that lightning travels several miles
to reach the earth. Tiny objects on the ground
have no influence on controlling the path
lightning takes through the air.
What do lightning rods look like?
In most cases unless you are looking for
the lightning rods you can’t notice them. Lightning rods are
just 12 inches tall and 3/8” in diameter. That’s
not much bigger than a pencil. Placed on a roof that is 30 –50
feet high and 18 inches in from the roof edge,
the rods are barely visible from ground.
There are a number of measures that can be taken to make lightning
protection even less noticeable. There are different materials
that can be chosen to blend with the architectural features,
style and materials. For instance, tin-plated copper can be chosen
to blend with gray stonework or copper blends well with dark
When designed during construction all of the lightning protection
system, except the rooftop terminals, can be concealed and run
inside the structure. There are also ways to avoid the use of
air terminals, such as substituting thick-walled metal railings
for the lightning rods. Decorative finials can also be used as
air terminals, making the lightning protection an architectural
If there is a steel frame in a building is it already safe?
The structural steel of a building does conduct
lightning, but you need a lightning protection system to provide
the necessary interconnections to make sure that the lightning
is able to pass harmlessly through the building.
Without the lightning protection system, when a building is
struck the lightning attempts to find a path to ground. If there
are not enough interconnections providing a continuous path for
the lightning to follow, there will be arcing or side-flashing.
The lightning will also travel on other mechanical systems in
a building such as the electrical or HVAC systems. The lightning
current jumping from object to object within a building is dangerous
and has been known to cause fires, explosions, etc.
What are the odds of a building getting hit anyway?
There are satellites that monitor lightning activity
all over the world. This activity is charted and provides statistics
that tell just how often lightning strikes any given area.
At any given moment there are 2000 thunderstorms happening
somewhere in the world. The earth experiences 100 lightning
flashes per second. The US alone has more than 40 million lightning
strikes each year. Any given square mile in the US can expect
approximately 40 strikes per year.
Some statistics regarding lightning damage include:
Between 1992 – 1996,
it is estimated by that 1.7 billion dollars were paid out
by insurance companies
in lightning related commercial claims.
The Insurance Information Institute
reports that approximately 5% of all commercial
claims are lightning related.
In 1996 a Federal judge
upheld a judgment levied by OSHA against
for failure to provide adequate lightning
protection, after two
workers were killed by a lightning caused
The US Fire Administration
reported in 2002 that it estimates 17,400 structural
fires are caused by lightning each year. Dollar
losses per lightning
fire are nearly twice
that of fires started
by other means.
What types of buildings need lightning protection?
Any structure is a good candidate for lightning
protection. All buildings are subject to
lightning damage. The NFPA 780 Risk Assessment guide is a useful
tool in evaluating
a structure’s vulnerability to lightning damage. A structures
use and contents are as much a consideration
as location and construction when determining lightning risk.
It is commonplace for lightning protection systems to be installed
on schools, hospitals, health care facilities, airports, shopping
centers, office buildings, manufacturing facilities, etc. In
some parts of the country there has been a move to mandate the
installation of lightning protection on certain types of buildings.
For example, in Florida, lightning protection systems are required
for installation on schools and health care facilities. Correctional
facilities are also required to have lightning protection systems.
How much does lightning protection cost?
Cost varies greatly depending on the location
of the structure, its size, its construction, the complexity
of the roof-line and the ground conditions. Costs are lower
when the system is designed and installed during construction.
Retrofitting a system, is very common, but tends to be slightly
more expensive. In comparison with other building systems,
such as security or plumbing, the lightning protection is usually
Doesn’t the electrician take
care of this?
Lightning protection does not fall under the
expertise of most electricians. Lightning rods have their own
NFPA standard that is separate from the National Electric Code
that electricians are trained on. Lightning protection work
should be performed by a lightning protection specialty contractor.
ECLE recommends using a firm that works full-time on lightning
protection; These firms are specialists, that are listed with
Underwriters Laboratories, certified by the Lightning Protection
Institute and familiar with the NFPA and UL requirements for
Isn’t the purpose of lightning
protection to prevent lightning from striking?
Nothing can prevent lightning from striking.
If lightning is zeroed in on a particular object it will strike
that object regardless of anything that is on the ground. The purpose
of lightning protection is to intercept the lightning strike and
carry it to ground. This is accomplished by placing the rods at
regular intervals on all of the highest and most exposed parts
of a structure. These rods become the most likely point for the
lightning streamer to attach, since they represent the shortest
path to ground. The rods are connected by a network of highly conductive
cables that provide a low-resistance path to ground.
Do I have to have all those cables running all over the roof?
Some cables are inevitable, but if the system
is installed during construction much of the system can be
run under the roof, leaving just the air terminals exposed.
The structural steel of a building can often be used in lieu
of conductors. This also limits the number of roof conductors
that you will see.
Do lightning rods really work?
Yes. The NFPA has maintained a standard for
lightning protection for 100 years. The standard is continually
and edited to incorporate new findings. For
example, in the last few years, sharp-tipped lightning rods
have been replaced
by blunt or round-tipped rods in NFPA requirements.
This is the result of field research at New Mexico Tech that
that blunt tipped rods are always successful
in capturing a lightning discharge in comparison to a sharp
tipped rod. The
NFPA’s standard is based on the same practices and principles
as standards for lightning protection all
over the world.
The FAA, NASA, Dept of Energy, and DoD typically do not build
any structures without lightning protection systems. In fact,
there was a federal report issued in 2004 that reviewed the technical
validity of lightning protection and concluded that lightning
protection systems are critical to protecting our national infrastructure.
The American Meteorological Society issued a similar paper in
Is lightning protection required?
Not always. There are different guidelines
in different parts of the country. Some Federal agencies require
lightning protection, other agencies have
if lightning protection is to be installed
it must comply with NFPA 780. For example, the Veteran’s
Administration requires UL Master Label Certification for all
installations. The Federal Bureau of Prisons
requires lightning protection systems. In Florida, the State
Building Code requires
lightning protection for all health care
facilities including, outpatient buildings and extended care
homes as well as for
What do design professionals need to know about lightning
Architects and engineers should be offering lightning
protection to their clients and making their clients aware that
without lightning protection, their buildings are at risk. The
NFPA 780 Risk Assessment guide is a helpful evaluation tool for
project planners. Designers can also review lightning protection
plans to ensure that the aesthetics of the building are not compromised.
For example, architects can recommend the use of railings in lieu
of air terminals for a particular parapet wall or the use of tin-plated
air terminals to blend with the color of the roof material.
Other things to be aware of when planning for lightning protection
might be provisions for chases if conductors are to be run inside
concrete walls and the use of compatible adhesives as recommended
by roofing manufacturers.