A few weeks ago, lightning strikes from overnight storms caused more than a dozen house fires in
North Texas. While some homes in Denton and McKinney survived with minor roof damage,
this home in Little Elm was completely gutted.
Lightning accounts for more than 2 billion dollars annually in structural damage
to buildings in the US but lightning protection systems are rarely used, especially on residential
buildings. In this video, we’re going to examine how lightning occurs and what we
can do to protect our buildings from it. Within a thundercloud, tiny bits of ice bump
into each other, creating electric charges. The positive charges or protons move to the top of the
cloud and the negative charges or electrons move to the bottom of the cloud. This causes positive
charges to build up on the ground. A network of channels called leaders or lightning flashes try
to neutralize the charged regions. A leader within a cloud is called a cloud flash, and a leader that
reaches the ground is called a ground flash. If it strikes a building, it can crack bricks and stone,
damage appliances, burn trees, and bring down power lines. Lightning can travel
long distances in underground or overground electrical wires, plumbing, radio or television
lines. Its unpredictability is scary, because you have no idea where or what it will hit.
Benjamin Franklin was the first to conduct a lightning rod experiment in 1752. Legend says
that he made a kite of silk and cedar with a wire attached to the top. To the bottom of the kite, he
attached a hemp string, silk ribbon and key. When he flew this kite during a storm and moved his
finger close to the metal key, he felt a spark. After the experiment, he designed a lighting
protection system that consisted of a sharp copper spike and cables running down to the ground.
The Franklin lightning protection system is still used today, more than 250 years later.
It consists of five main components. An air terminal or lightning rod which is
installed at the highest points of a building at regular intervals. They can be made of
conductive metals like copper or aluminum. Main conductors are braided copper or aluminum
cables that connect the lightning rod to the earth. Lightning travels on the outer surface of
these cables, so the more surface area available, the better. Copper is a better conductor,
but it’s often stolen on job sites, so people have been switching to aluminum.
Ground rods or electrodes are typically ½” wide, 10’ long copper rods driven 8 feet into
the ground. Do not use aluminium underground, it will corrode.
Bonding connects all metallic objects like roof components,
fans, water pipes, electrical systems, underground metal pipes, etc. to the main conductor.
Surge suppression is installed at electrical panels to protect appliances and prevent fires.
A surge is an increase in electrical current when lightning enters through the wiring system
instead of the lightning rod. Tree protection. Any tree taller than a home
or within 10 feet of the structure should ideally be equipped with a lightning protection system.
There is so much conflicting information about how these systems work and what they should look
like. The lightning dissipation theory says that lightning rods allow static charges to
bleed into the ground or the air, thus preventing a lightning strike. The lightning diversion theory
says rods don’t attract, repel, or prevent a lightning strike. They provide specific pathways
for lightning to travel safely into the ground. Researchers now lean towards the second theory.
Irrespective of what you believe, installing a lightning protection system is not a DIY project.
It’s advisable to hire a qualified lightning protection contractor.
It’s obviously easier during construction, but it’s still doable after.
The Franklin system is pretty cheap so it’s used for homes and mid-sized commercial buildings,
but it can get very complicated and expensive for large buildings. Indelec has developed an
Early Streamer Emission system (ESE) called the Prevectron. The National Lightning Protection
Corporation in Colorado sells these in the US. The Pevectron is completely powered by ambient air.
The lower electrodes collect energy from electrical fields and store it in capacitors.
As a lightning leader approaches a building, the Optimax system neutralizes the charge
around the tip of the air terminal. A patented trigger releases stored energy through the upper
electrodes in the form of a spark. The upward streamer meets the downward leader, and lightning
is directed safely into the ground. The newest version comes with a solar powered strike counter
so you can remotely check how many times the Prevectron has been struck by lightning.
The Prevectron system has a lot of advantages over the Franklin system for large buildings.
It can have up to 95% fewer parts. Just one Pevectron can protect this entire building as
opposed to 96 air terminals in the Franklin system. 2 roof penetrations instead of 22
reduces the risk of leaks and water damage. You can save time and money by using fewer wires and
ground conductors. While the Prevectron can be installed in 126 hours and cost $31,000
for this building, the Franklin system would take about 360 hours and cost around $68,000.
I don’t want this to turn into an ad for the Prevectron, but I really appreciate companies
that question the way things are done and invest in R&D to develop new, ground breaking products.
The LIRI research institute replicates real lightning discharge phenomena in a lab.
They use a metallic hanging plate, high voltage DC
generator that produces an electrical field and a Marx generator that produces a high impulse
voltage. This is an expensive technology though, it can save you money on large projects, but the
Franklin system is still ideal for homes. While making this video, I was surprised and
amused to find out that lightning protection systems are a hotly debated topic. Pointed
air terminals work best, no rounded terminals are better. Several spikes or a single one.
There are many organizations that don’t believe the effectiveness of Early Streamer Emission
systems and denounce it with passion but it seems like they’re referring to cheap knockoffs,
not the Prevectron. Anway, while the research continues, there’s no debate about the importance
and necessity of lightning protection systems. Let me know in the comments if you’ve dealt with
fires in your homes because of lightning strikes or if you’ve installed the Franklin system. Don’t
forget to hit the like button and subscribe to my channel. I’ll also link my Patreon page in the
description. If you can support me, I’d really appreciate it. Thanks for watching. See ya.