What Is an Electrical Power Surge?

D.P. Taylor
Written by D.P. Taylor
Updated July 2, 2021
shot of woman in gray shirt plugging in power cord of coffee pot to electrical outlet
Maskot/Maskot via Getty Images

An electrical power surge is a sudden and short increase in voltage in an electrical circuit, which can damage sensitive electronics

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Most of us feel pretty safe inside the house when a lightning storm is raging outside. But we're surrounded by a bunch of things that are in danger: our electronics.

One lightning strike in the right place and bam, a power surge hits your television. That means even when the power comes back on, the TV may not. Of course, lightning isn't the only cause of power surges—in fact, it’s not even the most common. Read on to learn about what power surges are, what causes them, and how to protect your electronics.

What Is an Electrical Power Surge?

Your electronics are fragile, and can only handle so much electrical current. If a surge of electricity overwhelms the electronic device's voltage limits, they can be "fried." And it may not happen all at once: Small power surges over time can gradually degrade your electronics.

More technically speaking, a surge is a transient wave of current or "overvoltage" that lasts a short period of time. These transients can sometimes contain tens of thousands of volts and last just microseconds.

What Causes a Power Surge?

While most people think of lightning strikes when they think of power surges, an estimated 60 to 80% of power surges come from inside the house. Yes, turning large appliances on and off or even flicking the thermostat switch are the most common power surge causes. 

Here’s a list of the typical causes of power surges:

  • Appliances (such as refrigerators, dishwashers, air conditioners, microwaves, and washing machines)

  • Lightning strikes

  • Bad wiring

  • Downed power lines

  • Bad equipment from the utility company

  • Tripped circuit breakers

  • Short circuits

  • Power outages

  • Power company malfunctions

Are Power Surges Dangerous?

While power surges are primarily a danger to sensitive electronics, they can be dangerous to people. A strong surge can cause an appliance to overheat or even catch fire.

The more severe the surge, the more likely it is to cause overheating and a fire. Switching appliances on and off doesn't cause as severe of a spike as, say, a lightning strike, but all surges carry a small risk of fire. While the risk is low, a surge protector can help protect you from potential disaster.

closeup of charger in electrical outlet with woman in bed on her phone blurry in the background
dowell/Moment via Getty Images

What Will a Power Surge Do to My Electronics?

Household electrical systems tend to run an alternating current rated at 120 volts and 60 hertz, but maxes out at 169 volts (with a minimum of 0).

A power surge causes the voltage to exceed 169 volts, which is harmful because it causes the electrical current to go above the normal operating voltage. This, in turn, creates an arc of electrical current that damages circuit boards and the various components that help run your appliances and devices. Smaller electrical surges cause damage more slowly and may shorten the lifespan of the device or appliance. This is why many homeowners deem surge protectors a good investment.

What Is a Surge Protector and How Does It Work?

A surge protector doesn't block the surge, it simply redirects a sudden increase in voltage into the ground.

Most surge protectors come in the form of a power strip that you can plug multiple devices into, protecting all of them at once. When the power spikes past a designated level of voltage, the surge protector diverts the extra current into grounding wires, giving the electricity a pathway away from the devices.

Does a Power Strip Protect From Surges?

While power strips and surge protectors look similar, only the surge protector will keep electronics from getting fried by excess electricity. A standard power strip is simply a device that allows you to have extra outlets. These strips are basically just extension cords without the additional protection.

Check the packaging to ensure it’s a surge protector before buying it—there should be a Joules rating on it. If it says 2,000 Joules, that means it can take 2,000 Joules worth of power surges before it’s no longer effective.

How Can I Protect My Home From Power Surges?

A surge protector isn't a fool-proof way of protecting your electronics. The surge protector could still be overwhelmed by a particularly strong power surge, or you may not have all devices you want to protect plugged up to it. Another way to protect your gadgets is to have an electrician inspect your wiring to ensure there are no flaws that could lead to a surge. 

The electrician may recommend updating your home’s electrical system. You could also buy a whole-home surge protector, which is hard-wired to the service panel. You'll need a professional to set that up.

Protect Your Electronics and Home From Power Surges

Electronics are expensive. One bad power surge and you could be out thousands of dollars in equipment. As a result, it's wise to take some steps to ensure your home is protected. 

A professional electrician can inspect your home, install whole-home surge protectors, and give you other safety recommendations. Find an electrician near you to keep your home and electronics protected from power surges.

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