Why You Can Trust CNET Why You Need a Surge Protector
Surge protectors can keep appliances safe and prevent electrical fires. Here's how they work and how to choose the right one for your home.
Power strips and surge protectors look the same, but only one protects your electronics.
The electricity in your home can seem to be constantly flowing: You flip a switch or plug something in and you're good to go.
In reality, that power fluctuates. If the voltage increases enough, the power surge can damage your electronics or even start a fire.
That's where surge protectors can help. These devices keep the wiring and appliances in your home from getting fried during a power surge. Here's what you need to know about surge protectors, including why you need one, how they keep electronics safe and how to choose one for your home.
What is a power surge?
Your home's electrical system typically sends 120 volts of power to your wall sockets and light fixtures, but that voltage isn't always constant. The power your home receives from the electrical grid fluctuates between zero and 169 volts. A power surge that can cause damage occurs when the voltage reaches above 169 volts.
Power surges can happen thanks to factors inside your home, including electrical overload -- like plugging too many devices into an extension cord -- and faulty wiring. External causes like lightning strikes, power outages due to peak demand or power supply switches at your electrical utility can also cause a surge.
"A power surge can take out everything that's important in your home. It can be a very expensive problem," said Eric Goranson, a Seattle-based designer and home renovation expert who hosts Around the House, a podcast and nationally syndicated radio show.
Most of the time, you won't even know a power surge has occurred as long as it's within that 169-volt range. However, surges of 170 volts and above can seriously damage electronics. That jump in voltage can cause arcing, which can damage delicate components inside electronics like computers and TVs or even cause them to catch fire. Lower-voltage, repeated power surges can shorten the life of appliances over time. An extreme surge can damage or destroy circuitry and power outlets in your home.
How does a surge protector guard your stuff?
You can keep your appliances and even your home's wiring safe with a surge protector. There are two different types: plug-in surge protectors, which resemble a power strip, and whole-house surge protectors.
Plug-in surge protectors work by absorbing and diverting a surge. The extra power is sent to the outlet's ground wire -- the third prong in modern electrical sockets -- and prevented from reaching any devices that are plugged into that socket.
Whole-house surge protectors don't just protect a few of your devices. Instead, these protectors are connected to your home's main electrical panel where they monitor the voltage coming into the system.
"When too much power comes in, a whole-house surge protector stops it from coming through to everything else," Goranson said, noting that a whole-house surge protector can protect your home's entire electrical system, including large appliances and HVAC systems. A whole-home surge protector can also prevent surges from damaging an EV charger.
Even a whole-house surge protector won't protect your electronics against millions of volts from a direct or nearby lightning strike, but they can handle power surges caused by potentially damaging lightning strikes further away. If you're especially concerned about damage to your electronics, be sure to unplug devices before a lightning storm hits your area even if you have surge protectors in place.
How do you choose a surge protector?
If you're a renter or on a tight budget, plug-in surge protectors are your best option for expensive or essential appliances like TVs, computers, gaming systems, phone chargers, routers, modems and medical equipment. Choose a model with the number of plugs you'll need and take factors like spacing into account to accommodate your devices.
Surge protectors are rated in joules, based on how many joules of power they're able to absorb from an electrical surge. A 200-400 rating is the minimum you'll want to consider, with the highest-rated surge protectors clocking in at 2,000 joules or more. Plug-in surge protectors cost around $15 to $25 each, with several plugs that can accommodate multiple appliances.
Homeowners may want to consider investing in a whole-house surge protector rather than individual plug-in protectors. That way, everything in your home that plugs into an outlet is protected -- including large appliances and your HVAC system that can't be plugged into power strip-style surge protectors -- as well as your electrical wiring itself. A whole-house surge protector costs anywhere from $80 to $300, in addition to the cost for a licensed electrician to install it for you.
"This is not a DIY project," said Goranson. "You need to bring in a licensed, bonded electrician to tackle it, because you're dealing with raw power coming in off the pole. That's something you don't want to mess with."
When it comes to choosing a whole-house surge protector, Goranson recommends asking your electrician for recommended brands and buying the device through them. They can make sure it's compatible with your electrical panel and handle the installation. Purchasing through a tradesperson comes with another advantage: In the event that there's an issue with the product while it's under warranty, the contractor deals with the manufacturer and saves you some hassle.
Frequently asked questions
Are surge protectors and power strips different?
Yes. Power strips and surge protectors might look similar, but only a surge protector will protect the appliances plugged into it from a surge.
Do surge protectors need to be replaced?
Most manufacturers of plug-in surge protectors recommend that the devices be replaced every three to five years. Both plug-in and whole-house surge protectors should have indicator lights to let you know whether they're operating properly. Make it a part of your home maintenance routine to check the status of your protectors regularly.
Do my devices have built-in surge protectors?
Some devices like laptop batteries and desktop computers may have some form of built-in surge protection, but it's likely not adequate to protect that device from repeated or strong surges. You'll still want to plug these into a surge protector strip or use a whole-house surge protector to prevent damage.