Do Surge Protectors Protect Against Lightning?

2017 Nov 27
Posted in: Electrical
what home improvements require a permit

No, surge protectors by themselves won’t protect your home from a surge caused by a direct (or even a nearby) lightning strike. In fact, completely unplugging appliances from the outlet is the only way to ensure 100% protection against lightning strike surges. 

That said, we know you probably aren’t going to unplug every electrical appliance in your home at the first sign of every thunderstorm.

The good news is that, according to the NEC (National Electric Code), surge protectors can offer “enhanced protection” against lightning strikes when:

  1. You install several layers of surge protectors
  2. You pair surge protectors with a lightning protection system

We’ll explain what “layering” surge protectors means and what a lightning protection system is. But first, let’s take a more in-depth look at why whole-home surge protectors by themselves can’t protect your appliances from lightning strikes.

Surge protectors alone can’t protect electronics from lightning

The electricity in a lightning bolt is much too powerful to be stopped by a surge protector.

To explain why, let’s first look at how surge protectors work.

A whole-home surge protector monitors the amount of voltage that enters your home. If a dangerous surge tries to enter your home, the surge protector immediately diverts the extra voltage into the earth via a “ground wire”.

The image below shows how a whole-home surge protector works during a “normal” voltage surge (i.e. a surge that wasn’t caused by a lightning strike). In this example, the surge is coming from the utility lines and through your main electrical panel.

How surge protector works
How a whole-home surge protector works during a normal surge (NOT a surge from a lightning strike). 

As you can see in the image above, surge protectors work by creating a break or “air gap” in the live wire. This “air gap” interrupts the flow of electricity to the electronic.

But this tiny air gap isn’t enough to stop the voltage from a lightning strike. Instead of rerouting easily to the ground wire, the voltage from a lightning strike is so powerful that it will “jump” the air gap in the live wire.

And when it jumps that gap, it will course through your home’s wiring and your electronics, frying the circuitry inside anything that’s plugged into an outlet.

The best protection against lightning strikes? Unplug or “layer up”

Like we mentioned earlier, the only way to guarantee that your electrical appliances survive a lightning strike is to completely disconnect them from your home’s electrical wiring.

For example, during a monsoon, you could unplug every appliance to guarantee that the overvoltage from a potential lightning strike wouldn’t fry any of your home’s electronics.

But if that sounds incredibly inconvenient, you do have one other option (if you’re willing to take your chances): Install a lightning protection system (LPS) along with several layers of surge protectors. 

IMPORTANT: 

  • Although this system (LPS + layered surge protectors) is encouraged by the NEC, it’s not 100% guaranteed to protect your electronics. Voltage could still leak through the LPS and surge protectors and into your electronics. 
  • It’s also important to note that in the event of a nearby or direct lightning hit, you’ll most likely need to replace your surge protectors as the amount of voltage from the lightning will probably fry them. Unfortunately, “failure due to direct lightning strikes” is not covered by most surge protectors’ warranties (seen below).

BUT if you’re still interested in providing some protection against lightning strikes, here’s a look at what you should install:

Layer 1: A lightning protection system

A lightning protection system (LPS) is designed to safely carry the majority of voltage from a lightning strike into the ground.

LPSs have 3 parts:

  1. A rod that intercepts the lightning strike
  2. Conductor cables that carry the electricity from the rod to the ground rods
  3. Ground rods (thick rods implanted deep into the ground) that complete a safe path for electricity to discharge into the ground

LPSs, on their own, can’t divert 100% of the voltage from a lightning strike, though. That’s because when lightning strikes, it doesn’t just follow one path to the ground. Instead, some voltage will find its way into your home’s wiring in an attempt to ground itself. 

And this is where your surge protectors come into play...

Layer 2: Two whole-home surge protectors

To provide the most protection against lightning strike overvoltage, you should install surge protectors between:

  1. The utility lines and your home’s electrical panel
  2. Your home’s electrical panel and your electrical appliances

By installing a surge protector between the utility lines and your electrical panel, you limit the amount of lightning surge voltage that’s able to come in from external wiring. From there, the surge protector between the electrical panel and your appliances will clamp down and divert even more voltage that finds its way into your home’s electrical system.

Whole-home surge protectors should be installed by a professional. To learn more about your options when it comes to whole-home surge protectors, check out our blog “How to Buy Surge Protectors For Your Home”.

Layer 3: “Point-of-use” surge protectors

Point-of-use surge protectors work the same way whole-home surge protectors do but instead of protecting the home’s entire electrical wiring, it protects just one (or more) appliance(s).

Point-of-use surge protectors sit between the outlet and the appliance it protects. So, when a lightning strike occurs, it can catch any leftover voltage that made its way past the LPS and the first 2 layers of surge protectors. The good news is that these surge protectors don’t require professional installation. In fact, you can find point-of-use surge protectors at most general stores and can install them easily on your own.

Need help from an Arizona electrician?

During monsoon season, Arizona is a high risk area for lightning strikes. If you’re interested in learning more about surge protection for your expensive electronics, we can help.

Just contact us. We’ll give you professional advice on the protection you need and, if needed, provide a fair quote for your whole-home surge protector installation.

Related reading: