Let’s Talk Lightning
Kids are splashing in the pool, hot dogs are sizzling on the grill, air condition bills are on the rise, and it’s starting to feel like a sauna outside. Ah, summer is here.
And so are thunderstorms.
If you live anywhere near us – outside of Philadelphia, you’re no stranger to the frequent afternoon or middle-of-the-night summer thunderstorm. What’s better than losing power in the middle of a hot day while you’re giving a webinar? Or what about that 2 am thunder crackle that shakes your entire home, waking up your whole family and dogs? I certainly can’t think of anything more pleasant.
Kidding. I can’t stand thunderstorms. While I am probably not completely alone in this opinion, a lot of people love them. I won’t comment on that because I still can’t wrap my head around the concept.
Nevertheless, what I do love is some good protection from a thunderstorm. While some people like to sit on their balcony watching the storms roll in, you can find me hiding inside. Blackout curtains, an apartment with underground power lines, and a great white noise machine – I am all in. That’s my kind of protection from a storm.
But there’s another kind of protection we can (and should) all get behind when it comes to storms. Lighting Protection.
Let’s start with the basics though.
What actually is lightning?
A lightning strike is basically a massive electric spark that’s either traveling between the clouds or from a cloud down to earth. Since it’s an uncontrollable natural phenomenon, scientists can only give a best estimate that lightning is anywhere from 30 to 50 million volts.
With that kind of voltage – regardless of where it really falls within that range – protection from lightning is a no brainer. To put things in perspective, most household outlets are designed for 120 volts. In commercial high voltage applications, you may see voltages greater than 100 kV (kilovolts). Still, no where near a million volts. That’s a wild amount.
Fortunately, protection against lightning is possible.
How are we protected from lightning?
Well – there’s three steps. Intercepting the discharge. Safely conducting the lightning currents while minimizing the effects. Dissipating the currents into the earth.
Now, we just need the technology that can do all of it.
Luckily, we’ve got that too, thanks to lightning protection systems. It typically starts with a strike termination device (or lightning rod), which is the first point of contact with lightning. The rod will deflect the lightning stroke into the protective system itself, where it is rerouted away from the building – to the ground – eliminating the potential for damage.
So, what do you need to know about these superhero protecting devices? Well, we’re going to tell you.
I think part of my distrust of lightning comes from the fact that I grew up on the west coast, and we didn’t have frequent thunderstorms. I honestly can’t remember thunderstorms ever happening. I am sure they did, but nothing like over here on the east coast.
With that said, location matters. If you’re installing a lightning protection system, one of the most important things to consider is the frequency of lightning in the area. This varies widely across the country, as I’ve illustrated above.
When we’re talking about location, what’s around the area matters too. My mom would always say, “Don’t worry, lightning strikes the tallest object.” While I didn’t find this particularly comforting, she wasn’t wrong.
However, according to NOAA, lightning tends to strike the tallest object, but not always.
So, when you’re installing a lightning protection system, you need to be aware of the surrounding structures and landscape, especially anything that rises 50 feet above adjacent structures.
What about the structure itself?
Yes, that matters too. The lightning protection system in a commercial building is not going to look like the one for your home or for your nearby hospital.
Also, the physical construction of the building should not be overlooked. The frame, roof, and building materials – like wood, concrete, or steel – all make a difference when it comes to lightning protection.
Where do you put it?
Well, if by it, you’re talking about the strike termination device or lightning rod, then it’s going to go on the roof. Depending on the type of roof – slanted, pitched, etc. – there are different standards to follow.
Which brings us to a great point.
Who makes the rules for lightning protection?
The applicable standards for lightning protection are NFPA 70 and 780 and UL 96 and 96A. If you’re into that kind of thing, feel free to go read the standards more closely. If not, just read this blog. Where do you think we got all of this information anyways?
But what else is involved in a lightning protection system?
In addition to a lightning rod or other termination in the air, there’s also going to be a ground rod, conductors, connectors, and fittings.
The rods in the air will intercept the lightning discharge and direct the current to a safe path to ground – providing a zone of protection. The conductors will then concentrate the lightning current in a safe path away from your home, equipment, building, or people nearby. These low impedance paths are typically made of copper or aluminum. If you want to improve the effectiveness of your lightning protection system, multiple parallel paths can help. Finally, a low resistance ground termination will dissipate the current into the earth.
Grounding electrodes can range in complexity from a single rod to meshes or large grids. At the end of the day though, they all do essentially the same thing, but some provide a larger interface with the soil to overcome tricky earth conditions.
The last things we need to talk about are connectors and fittings. These simply bond conductors to terminals and building structure, and it’s very important that they are tight and well maintained.
And that’s the lightning talk. Stay safe and go check on your lightning protection system!
Want to learn more about ground testing and lightning protection? Check out our complete guide to ground testing.
- Meredith Kenton, Digital Marketing Specialist Have an idea for a blog? Email Me