Are Metal Buildings Safe From Lightning?
So you're worried about a metal building getting hit by lightning? Don't worry, we've all been there. I've got GOOD news and GREAT news...
Here's the deal:
Long story short, lightning is not actually attracted to anything specifically. Lightning can strike anything. This is the GOOD news.
"Lightning occurs on too large of a scale to be influenced by small objects on the ground, including metal objects."
The common myth is that metal buildings are more prone to lightning strikes than any other type of structure. In other words, metal buildings or metal roofs are basically lightning magnets. Makes sense, right?
There are a ton of other crazy myths along the lines of:
- Being safe outside as long as you're not wearing (metal) jewelry.
- Wearing metal cleats or having something with metal on you is prone to get struck.
But you're thinking:
Yeah, but what is lightning really attracted to?
Most of us know that when you see lightning and count how many seconds are between the light and the big crash, are the approximate amount of miles you are to the storm.
So, instead of worrying about lightning having it in for you or your building...
Here's what you need to know:
Lightning does not care about the small amount of metal that you may have on or be carrying around.
It cares about what is higher off of the ground.
What happens when lightning strikes metal?
On the slight chance that a steel building or roof is struck by lightning, it is less likely to result in a fire than other types of roofing materials.
This is because the grounding of the building creates a more secure way for the lightning to travel.
Take this extra precautions and increase your safety
(This is the GREAT news.) Since metal buildings are not being singled out from being prone to lightning, you can take extra precautions to make sure you and your steel building(s) are safe.
As it turns out...
The Metal Construction Association breaks this situation into 2 parts:
- The probability of lightning hitting your home or building
- What actually happens when lightning strikes
Steel is not a lightning magnet. But you can deter the lightning if it does happen to strike your home or building.
A metal building and roof will survive a lightning strike with less damage that
Should a metal roof or building be grounded?
Our answer would be a definite yes!
The rod is simply another piece of metal if it is not grounded, meaning, there is no point of having the rod prevent the lightning strike without having it grounded into the earth.
Now we're taking a few extra preventative measures:
- A lightning rod
- Concrete foundation
Should you be concerned about getting a metal building or metal roof on your home?
Not at all.
Is this the best option?
Steel roofs will, in fact, be less dangerous when they are struck by lightning even without a lightning rod. Yes, you read that right, less dangerous!
How to install a lightning rod to a metal roof?
In simplest terms...
The copper poles connect to cables, which then run down the side of the building into the ground.
The best part?
The rod is designed to draw all the negative charge of the electricity from the building.
Basically, the rod draws all the electricity to itself and transfers it to a system of cables (made up of copper or aluminium wire) so that the building is protected from the charge of electricity.
The wire travels down 10 feet into the ground, to a ground rod. The is known as "grounding a lightning rod."
Getting the ground rod into the ground: electric ground rod hammer
How to Install a Lightning Protection System
How a Lightning Rod or Lightning Protection System (LPS) Works
- Lightning is a flow of electrical current between the earth and the sky. The result of the electrical flow can be millions of volts and its costs can be billions of dollars of lightning-related damage annually.
- Some people falsely believe 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 lighting protection system (LPS) that will dissipate lightning's harmful electricity safely to ground.
- When lightning strikes, a 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.
Before You Install a 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.
- 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.
- 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.
- Next, slide the ridge cap over the rod and make sure the clips are fastened firmly along the metal roof lining.
- Now it's time to slide the three-legged galvanized scroll brace down the rod. You're all set.
Metal roofs have a ton of advantages: