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Critical Electric Systems Group

Imagine the sight of Ben Franklin flying a kite in a rain storm. His neighbors probably thought he was a few

cards shy of a deck. If we saw that today, we’d try to stop him before he did serious damage to himself.

Maybe not knowing what we know about lightning today insulated him from getting into real trouble.

We’ve all heard stories and seen photos of the damage and strange effects of lightning strikes on buildings.

If there’s one thing we’ve learned it’s that lightening is a powerful force and we’re a long way from taming it.

  •  A lightning bolt can generate up to 35,000 to 40,000 amps.
  •  All lightning is heat lightning, it’s can be hot as 90,032°F
  •  Think you’re safe? Lightning strikes the earth somewhere 100 times a second, but kills only 100 Americans a year.
  • Annually in the USA lightning causes more than 26,000 fires with damages of $5-6 billion.

Several years ago in Denver lightening struck and caught fire to a building resulting in $50 millions in damages.

According The Weather Channel this was the costliest civilian lightning loss in U.S. history.

 

Lightning is the number one cause of petroleum storage tank explosions with 16 of 20 explosions chalked up to

lightning strikes in a recent years. It only takes one bolt to cause damage as seen in the famous 1926 U.S

Naval munitions dump in New Jersey. The single hit killed 19 military and civilian workers, injured 78 and

caused $50 million in damages in 1926 dollars.

Understanding lightning will improve our ability to protect our buildings from lightning damage, but there is no

100% safe-guard. (Be very afraid of anyone who promises complete protection!) Do as Ben Franklin who

called us to protect all those beautiful building in Philadelphia with multiple levels of protection. Not all

methods and techniques will work or are needed in all buildings.

1. Grounding

Ben Franklin was an early user of grounding. While the principle is still the same we have multiple methods to

keep the power of lightning out of your building.

Lightning Rods are the most familiar grounding protection. Ben Franklin understood the theory of making a

lightning target and directing the resultant strike harmlessly to the ground. Different designs work in different

environments and meet different requirements. The wires over utility substations act as lightning rods, although

we call them air terminals today. Other applications are definitely not suited for air terminals like the munitions

dump in New Jersey or where electronics need to be protected within structures. A Faraday Cage is a good

choice for those buildings.

Downconductors, like lightning rods, direct current to ground to prevent lightning damage. Building steel may

be used in place of downconductors where practical as a beneficial part of the earth electrode subsystem.

2. Transients and Surges

To a lightning bolt building wiring, fuses and circuit breakers are all the same. They’re all conductors. They’re

also not capable of dealing with the extreme flow of current suddenly added to the system by lightning. These

lightning-induced transients are controlled with Transient Voltage Surge Suppressor (TVSS) equipment.

They’re our high tech answer to a switch that shuts off power as soon as any rise is identified. A TVSS shunts,

filters, clamps or blocks energy from traveling down the wire. Getting the right combination of methods

requires a partner who understands the equipment, codes and standards, the types of equipment in and

around your campus and, of course, your application.

3. Detection

There is a lot of controversy about being able to detect lightning and then being able to detect it in time to avoid

damage. One aim of detection is to be able to switch from AC line power to standby power. This way the

system is not interrupted and the main AC power is not subject to lightning damage. We recommend a plan on

what is to be protected, what is the cost and what is the level of confidence you need.

4. Remain Vigilant

Lightning is out there. Weather, time, changes to the building and maintenance can all have an effect on the

resistance to lightning. An inspection of your lightning protection and a review of what’s now available could

save you a lot of headaches, and perhaps save you from seeing stars.

Please contact us to inquire further on how we can help protect your facility from lightning and its costly

damage. As Ben Franklin would say, an ounce of prevention is worth a pound of cure.