Are Metal Buildings Safe From Lightning?

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We’re investigating the real relationship of lightning to metal and addressing your safety concerns when it comes to a metal building’s ability to withstand one of Mother Nature’s most worrisome weather conditions. (Spoiler Alert: it’s good news)

Lightning Myth – Busted

Installing a metal roof may have you concerned when it comes to an old urban legend we’re all familiar with: that metal attracts lightning like table scraps to hungry dogs.

If that’s the case, we’ve got good news.

It’s not true.

Long story short, a metal roof will not increase your building’s chances of being struck by lightning, but conversely will make a lightning strike less dangerous if it does, by chance, happen to occur.

It’s a scientific fact that lightning is not actually attracted to specific objects, surfaces or types of material. Lightning can strike anything and occurs on too large of a scale to be influenced by distant objects on the ground, yes that includes metal.

Most of us have learned that counting the seconds between the flash of lightning and the crash of thunder will help measure the approximate distance in number of miles from your location to the storm, which is actually a much more accurate way of understanding the threat of an incoming storm to your home or building.

Stress over lightning is a valid concern for any property owner, but knowing the facts makes a major difference in ensuring proper preparation. So, instead of worrying about lightning having it in for your sturdy metal roof, know that the proximity of a storm is more of a determining factor than anything else. And that there is currently no known material that will decrease the likelihood of a strike.

Personal Safety During Lightning Storms

If your home or building has a metal roof and you are inside it during a lightning storm, are you more likely to be in danger?

No, in fact, the best thing you can do for your own personal safety during a thunderstorm is to head indoors.

In the case of a metal roofed building, any electricity from a lightning strike will be safely transferred to the ground below so occupants will be unaffected. Plus, metal’s inflammable nature means your home will be even more safe should the rare chance of a lightning strike actually take place.

Let’s Say A Lightning Strike DOES Happen.

lightning behind dark houses

On the off chance that your steel building or roof is struck by lightning, it is less likely to result in a fire than any other type of roofing material.

Why?

This is because the fixed grounding of such a building creates a more secure way for lightning to travel.

Although we’ve learned that metal buildings are not more prone to lightning strikes, we still encourage responsible owners to review the extra precautions listed below to better protect their property.

The Metal Construction Association Breaks This Situation into Two Parts:

  1. The probability of lightning striking your home or building
  2. What actually happens when lightning strikes

As we’ve stated before, steel is not a lightning magnet. However, it does have the capacity to decrease the destructive impact, should lightning strike your home or building.

It’s important to note:

That a metal building or roof will likely survive a lightning strike with significantly less damage when compared to other building materials.

You may also be asking, should a metal roof be grounded? Our answer is yes.

A “grounded” lightning pole is installed with a ground rod hammer, 10-feet below the surface of the earth. A grounding system connected to the earth will help to absorb the impact and equalize your buildings electrical systems, in the event of a hazardous lightning strike.

Did you know?

That steel roofs are in fact, less dangerous when struck by lightning, even without a grounded lightning rod. Steel roofs are one of the most reliable building resources in today’s modern marketplace.

Extra preventative measures include

  1. A lightning rod
  2. Concrete foundation
  3. Grounding

Here’s How a Lightning Rod is Installed on a Metal Roof

  1. The copper poles connect to cables
  2. The cables run down the side of the building & into the ground.

To ensure the highest standard in safety, the rod is designed to draw all the negative charge of electricity from the building. The rod ingenuously draws all electricity to itself and transfers it to a system of cables, made up of copper or aluminum wire, so that the building is protected from the intense surge of electricity.

The Basics in Lightning Protection Systems (LPS)

  • Lightning is a flow of electrical current between the earth and the sky. The result of this dangerous electrical flow results in billions of dollars of lightning-related damage, annually.
  • It is a false belief that metal roofs can increase the risk of a lightning strike. Metal roofs are no more attractive to lightning than any other type of roofing material.
  • While a building’s structural steel will conduct lightning, it is the bonding, interconnection and grounding provided by a lightning protection system (LPS) that will dissipate lightning’s harmful electricity safely to the ground.
  • When lightning strikes, an LPS offers assurance. An effective LPS not only protects roofs, walls and other structural components from direct lightning strikes, but it also shields electrical circuits, communications, process control systems and other elements that are vulnerable to indirect strikes.
How to install a lightning protection system

Before You Install an LPS

A safety standard compliant system provides proven and effective grounding to dissipate lightning’s harmful electrical discharge by employing a grounding network, which must include:

  • Strike termination devices (air terminals or rods)
  • Conductors (which can include conductive structural members)
  • Appropriate Interconnecting components such as connectors and fittings required to complete the system
  • Bonding to reduce potential differences created by the lightning current.
  • Grounding electrodes (ground rods, plates or conductors) installed to direct the lightning current deeply into the earth
  • Surge protective devices (SPDs) installed at every service entrance to filter the intrusion of lightning from utility lines and further equalize potential between grounded systems during lightning events

Installing a Lightning Protection System

  • Opposite charges of electricity attract one another – every structure on the ground has a negative charge of electricity on it.
  • When a lightning storm hovers over those structures, the clouds are charged with positive charges which attract anything nearby with negative charges (trees, buildings, cars, people, etc.)
  • By installing a lightning rod over a structure, such as a house, for instance, the negative charge can be drawn, which is safely “diverted” into the ground through a series of cables.
  • The cable should be a 17-gauge red copper wire, which goes 10 feet into the earth for proper grounding. An electric ground rod hammer can be used to drive the copper wire into the ground.
  1. Remove the ridge cap from both opposite ends of the building (e.g. north/south or east/west) because a scroll brace will need to be mounted on both opposite ends of the roof.
  2. A scroll brace made from galvanized steel is fastened to the ridge cap along with the copper lightning rod, polar ball (with brass collars on top and bottom) and directional arrow which is then mounted on the roof.
    • The lightning rod is not designed to attract lightning, but rather give it a safe path to ground – the idea is to draw negative charge from the building and drive it straight into ‘neutral’ ground.
  3. Slide the ridge cap over the rod and make sure the clips are fastened firmly along the metal roof lining.
  4. Finally, once you slide the three-legged galvanized scroll brace down the rod, you’re all set.

More Advantages of Metal Roofs

  • Metal roofs are resistant to wind, snow and hail
  • Metal roofs do not crack, peel or rot like shingles.
  • Metal roofs are more structurally sound, particularly in storm scenarios.
  • Metal roofs are mold and termite resistant.
  • Metal roofs are more energy-efficient and can even be made from 100% recyclable products
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